[PATCH v2 0/2] net: qrtr: Drop the MHI 'auto_queue' feature

[PATCH v2 0/2] net: qrtr: Drop the MHI 'auto_queue' feature

[Manivannan Sadhasivam via B4 Relay]

Hi,

This series intends to fix the race between the MHI stack and the MHI client
drivers due to the MHI 'auto_queue' feature. As it turns out often, the best
way to fix an issue in a feature is to drop the feature itself and this series
does exactly that.

There is no real benefit in having the 'auto_queue' feature in the MHI stack,
other than saving a few lines of code in the client drivers. Since the QRTR is
the only client driver which makes use of this feature, this series reworks the
QRTR driver to manage the buffer on its own.

Testing
=======

Tested on Qcom X1E based Lenovo Thinkpad T14s laptop with WLAN device.

Merge Strategy
==============

Since this series modifies many subsystem drivers, I'd like to get acks from
relevant subsystem maintainers and take the series through MHI tree.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
Changes in v2:
- Used mhi_get_free_desc_count() to queue the buffers
- Collected tags
- Link to v1: https://lore.kernel.org/r/20251217-qrtr-fix-v1-0-f6142a3ec9d8@oss.qualcomm.com

---
Manivannan Sadhasivam (2):
      net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels
      bus: mhi: host: Drop the auto_queue support

 drivers/accel/qaic/mhi_controller.c   | 44 -------------------
 drivers/bus/mhi/host/init.c           | 10 -----
 drivers/bus/mhi/host/internal.h       |  3 --
 drivers/bus/mhi/host/main.c           | 81 +----------------------------------
 drivers/bus/mhi/host/pci_generic.c    | 20 +--------
 drivers/net/wireless/ath/ath11k/mhi.c |  4 --
 drivers/net/wireless/ath/ath12k/mhi.c |  4 --
 include/linux/mhi.h                   | 14 ------
 net/qrtr/mhi.c                        | 69 ++++++++++++++++++++++++-----
 9 files changed, 62 insertions(+), 187 deletions(-)
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251217-qrtr-fix-c058251d8d1a

Best regards,
-- 
Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

[PATCH v2 1/2] net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

MHI stack offers the 'auto_queue' feature, which allows the MHI stack to
auto queue the buffers for the RX path (DL channel). Though this feature
simplifies the client driver design, it introduces race between the client
drivers and the MHI stack. For instance, with auto_queue, the 'dl_callback'
for the DL channel may get called before the client driver is fully probed.
This means, by the time the dl_callback gets called, the client driver's
structures might not be initialized, leading to NULL ptr dereference.

Currently, the drivers have to workaround this issue by initializing the
internal structures before calling mhi_prepare_for_transfer_autoqueue().
But even so, there is a chance that the client driver's internal code path
may call the MHI queue APIs before mhi_prepare_for_transfer_autoqueue() is
called, leading to similar NULL ptr dereference. This issue has been
reported on the Qcom X1E80100 CRD machines affecting boot.

So to properly fix all these races, drop the MHI 'auto_queue' feature
altogether and let the client driver (QRTR) manage the RX buffers manually.
In the QRTR driver, queue the RX buffers based on the ring length during
probe and recycle the buffers in 'dl_callback' once they are consumed. This
also warrants removing the setting of 'auto_queue' flag from controller
drivers.

Currently, this 'auto_queue' feature is only enabled for IPCR DL channel.
So only the QRTR client driver requires the modification.

Fixes: 227fee5fc99e ("bus: mhi: core: Add an API for auto queueing buffers for DL channel")
Fixes: 68a838b84eff ("net: qrtr: start MHI channel after endpoit creation")
Reported-by: Johan Hovold <johan@kernel.org>
Closes: https://lore.kernel.org/linux-arm-msm/ZyTtVdkCCES0lkl4@hovoldconsulting.com
Suggested-by: Chris Lew <quic_clew@quicinc.com>
Acked-by: Jeff Johnson <jjohnson@kernel.org> # drivers/net/wireless/ath/...
Cc: stable@vger.kernel.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/accel/qaic/mhi_controller.c   | 44 ----------------------
 drivers/bus/mhi/host/pci_generic.c    | 20 +---------
 drivers/net/wireless/ath/ath11k/mhi.c |  4 --
 drivers/net/wireless/ath/ath12k/mhi.c |  4 --
 net/qrtr/mhi.c                        | 69 +++++++++++++++++++++++++++++------
 5 files changed, 60 insertions(+), 81 deletions(-)

diff --git a/drivers/accel/qaic/mhi_controller.c b/drivers/accel/qaic/mhi_controller.c
index 13a14c6c6168..4d787f77ce41 100644
--- a/drivers/accel/qaic/mhi_controller.c
+++ b/drivers/accel/qaic/mhi_controller.c
@@ -39,7 +39,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -55,7 +54,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -71,7 +69,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -87,7 +84,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -103,7 +99,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -119,7 +114,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -135,7 +129,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -151,7 +144,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -167,7 +159,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -183,7 +174,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -199,7 +189,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -215,7 +204,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -231,7 +219,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -247,7 +234,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -263,7 +249,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -279,7 +264,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -295,7 +279,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -311,7 +294,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -327,7 +309,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -343,7 +324,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -359,7 +339,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -375,7 +354,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -391,7 +369,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -407,7 +384,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -423,7 +399,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -439,7 +414,6 @@ static const struct mhi_channel_config aic100_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = true,
 		.wake_capable = false,
 	},
 };
@@ -458,7 +432,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -474,7 +447,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -490,7 +462,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -506,7 +477,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -522,7 +492,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -538,7 +507,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -554,7 +522,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -570,7 +537,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -586,7 +552,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -602,7 +567,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -618,7 +582,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -634,7 +597,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -650,7 +612,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -666,7 +627,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -682,7 +642,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -698,7 +657,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -714,7 +672,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 		.wake_capable = false,
 	},
 	{
@@ -730,7 +687,6 @@ static const struct mhi_channel_config aic200_channels[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = true,
 		.wake_capable = false,
 	},
 };
diff --git a/drivers/bus/mhi/host/pci_generic.c b/drivers/bus/mhi/host/pci_generic.c
index e3bc737313a2..0884a384b77f 100644
--- a/drivers/bus/mhi/host/pci_generic.c
+++ b/drivers/bus/mhi/host/pci_generic.c
@@ -94,22 +94,6 @@ struct mhi_pci_dev_info {
 		.doorbell_mode_switch = false,		\
 	}
 
-#define MHI_CHANNEL_CONFIG_DL_AUTOQUEUE(ch_num, ch_name, el_count, ev_ring) \
-	{						\
-		.num = ch_num,				\
-		.name = ch_name,			\
-		.num_elements = el_count,		\
-		.event_ring = ev_ring,			\
-		.dir = DMA_FROM_DEVICE,			\
-		.ee_mask = BIT(MHI_EE_AMSS),		\
-		.pollcfg = 0,				\
-		.doorbell = MHI_DB_BRST_DISABLE,	\
-		.lpm_notify = false,			\
-		.offload_channel = false,		\
-		.doorbell_mode_switch = false,		\
-		.auto_queue = true,			\
-	}
-
 #define MHI_EVENT_CONFIG_CTRL(ev_ring, el_count) \
 	{					\
 		.num_elements = el_count,	\
@@ -329,7 +313,7 @@ static const struct mhi_channel_config modem_qcom_v1_mhi_channels[] = {
 	MHI_CHANNEL_CONFIG_UL(14, "QMI", 4, 0),
 	MHI_CHANNEL_CONFIG_DL(15, "QMI", 4, 0),
 	MHI_CHANNEL_CONFIG_UL(20, "IPCR", 8, 0),
-	MHI_CHANNEL_CONFIG_DL_AUTOQUEUE(21, "IPCR", 8, 0),
+	MHI_CHANNEL_CONFIG_DL(21, "IPCR", 8, 0),
 	MHI_CHANNEL_CONFIG_UL_FP(34, "FIREHOSE", 32, 0),
 	MHI_CHANNEL_CONFIG_DL_FP(35, "FIREHOSE", 32, 0),
 	MHI_CHANNEL_CONFIG_UL(46, "IP_SW0", 64, 2),
@@ -762,7 +746,7 @@ static const struct mhi_channel_config mhi_telit_fn980_hw_v1_channels[] = {
 	MHI_CHANNEL_CONFIG_UL(14, "QMI", 32, 0),
 	MHI_CHANNEL_CONFIG_DL(15, "QMI", 32, 0),
 	MHI_CHANNEL_CONFIG_UL(20, "IPCR", 16, 0),
-	MHI_CHANNEL_CONFIG_DL_AUTOQUEUE(21, "IPCR", 16, 0),
+	MHI_CHANNEL_CONFIG_DL(21, "IPCR", 16, 0),
 	MHI_CHANNEL_CONFIG_HW_UL(100, "IP_HW0", 128, 1),
 	MHI_CHANNEL_CONFIG_HW_DL(101, "IP_HW0", 128, 2),
 };
diff --git a/drivers/net/wireless/ath/ath11k/mhi.c b/drivers/net/wireless/ath/ath11k/mhi.c
index acd76e9392d3..d2c44f7f9b62 100644
--- a/drivers/net/wireless/ath/ath11k/mhi.c
+++ b/drivers/net/wireless/ath/ath11k/mhi.c
@@ -34,7 +34,6 @@ static const struct mhi_channel_config ath11k_mhi_channels_qca6390[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 	},
 	{
 		.num = 21,
@@ -48,7 +47,6 @@ static const struct mhi_channel_config ath11k_mhi_channels_qca6390[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = true,
 	},
 };
 
@@ -99,7 +97,6 @@ static const struct mhi_channel_config ath11k_mhi_channels_qcn9074[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 	},
 	{
 		.num = 21,
@@ -113,7 +110,6 @@ static const struct mhi_channel_config ath11k_mhi_channels_qcn9074[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = true,
 	},
 };
 
diff --git a/drivers/net/wireless/ath/ath12k/mhi.c b/drivers/net/wireless/ath/ath12k/mhi.c
index 08f44baf182a..2dbdb95ae7be 100644
--- a/drivers/net/wireless/ath/ath12k/mhi.c
+++ b/drivers/net/wireless/ath/ath12k/mhi.c
@@ -31,7 +31,6 @@ static const struct mhi_channel_config ath12k_mhi_channels_qcn9274[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 	},
 	{
 		.num = 21,
@@ -45,7 +44,6 @@ static const struct mhi_channel_config ath12k_mhi_channels_qcn9274[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = true,
 	},
 };
 
@@ -96,7 +94,6 @@ static const struct mhi_channel_config ath12k_mhi_channels_wcn7850[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = false,
 	},
 	{
 		.num = 21,
@@ -110,7 +107,6 @@ static const struct mhi_channel_config ath12k_mhi_channels_wcn7850[] = {
 		.lpm_notify = false,
 		.offload_channel = false,
 		.doorbell_mode_switch = false,
-		.auto_queue = true,
 	},
 };
 
diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
index 69f53625a049..80e341d2f8a4 100644
--- a/net/qrtr/mhi.c
+++ b/net/qrtr/mhi.c
@@ -24,13 +24,25 @@ static void qcom_mhi_qrtr_dl_callback(struct mhi_device *mhi_dev,
 	struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev);
 	int rc;
 
-	if (!qdev || mhi_res->transaction_status)
+	if (!qdev || (mhi_res->transaction_status && mhi_res->transaction_status != -ENOTCONN))
 		return;
 
+	/* Channel got reset. So just free the buffer */
+	if (mhi_res->transaction_status == -ENOTCONN) {
+		devm_kfree(&mhi_dev->dev, mhi_res->buf_addr);
+		return;
+	}
+
 	rc = qrtr_endpoint_post(&qdev->ep, mhi_res->buf_addr,
 				mhi_res->bytes_xferd);
 	if (rc == -EINVAL)
 		dev_err(qdev->dev, "invalid ipcrouter packet\n");
+
+	/* Done with the buffer, now recycle it for future use */
+	rc = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, mhi_res->buf_addr,
+			   mhi_dev->mhi_cntrl->buffer_len, MHI_EOT);
+	if (rc)
+		dev_err(&mhi_dev->dev, "Failed to recycle the buffer: %d\n", rc);
 }
 
 /* From QRTR to MHI */
@@ -72,6 +84,29 @@ static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb)
 	return rc;
 }
 
+static int qcom_mhi_qrtr_queue_dl_buffers(struct mhi_device *mhi_dev)
+{
+	u32 free_desc;
+	void *buf;
+	int ret;
+
+	free_desc = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
+	while (free_desc--) {
+		buf = devm_kmalloc(&mhi_dev->dev, mhi_dev->mhi_cntrl->buffer_len, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+
+		ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, buf, mhi_dev->mhi_cntrl->buffer_len,
+				    MHI_EOT);
+		if (ret) {
+			dev_err(&mhi_dev->dev, "Failed to queue buffer: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
 static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
 			       const struct mhi_device_id *id)
 {
@@ -87,20 +122,30 @@ static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
 	qdev->ep.xmit = qcom_mhi_qrtr_send;
 
 	dev_set_drvdata(&mhi_dev->dev, qdev);
-	rc = qrtr_endpoint_register(&qdev->ep, QRTR_EP_NID_AUTO);
-	if (rc)
-		return rc;
 
 	/* start channels */
-	rc = mhi_prepare_for_transfer_autoqueue(mhi_dev);
-	if (rc) {
-		qrtr_endpoint_unregister(&qdev->ep);
+	rc = mhi_prepare_for_transfer(mhi_dev);
+	if (rc)
 		return rc;
-	}
+
+	rc = qrtr_endpoint_register(&qdev->ep, QRTR_EP_NID_AUTO);
+	if (rc)
+		goto err_unprepare;
+
+	rc = qcom_mhi_qrtr_queue_dl_buffers(mhi_dev);
+	if (rc)
+		goto err_unregister;
 
 	dev_dbg(qdev->dev, "Qualcomm MHI QRTR driver probed\n");
 
 	return 0;
+
+err_unregister:
+	qrtr_endpoint_unregister(&qdev->ep);
+err_unprepare:
+	mhi_unprepare_from_transfer(mhi_dev);
+
+	return rc;
 }
 
 static void qcom_mhi_qrtr_remove(struct mhi_device *mhi_dev)
@@ -151,11 +196,13 @@ static int __maybe_unused qcom_mhi_qrtr_pm_resume_early(struct device *dev)
 	if (state == MHI_STATE_M3)
 		return 0;
 
-	rc = mhi_prepare_for_transfer_autoqueue(mhi_dev);
-	if (rc)
+	rc = mhi_prepare_for_transfer(mhi_dev);
+	if (rc) {
 		dev_err(dev, "failed to prepare for autoqueue transfer %d\n", rc);
+		return rc;
+	}
 
-	return rc;
+	return qcom_mhi_qrtr_queue_dl_buffers(mhi_dev);
 }
 
 static const struct dev_pm_ops qcom_mhi_qrtr_pm_ops = {

-- 
2.48.1

[PATCH v2 2/2] bus: mhi: host: Drop the auto_queue support

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Now that the only user of the 'auto_queue' feature, (QRTR) has been
converted to manage the buffers on its own, drop the code related to it.

Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/bus/mhi/host/init.c     | 10 -----
 drivers/bus/mhi/host/internal.h |  3 --
 drivers/bus/mhi/host/main.c     | 81 +----------------------------------------
 include/linux/mhi.h             | 14 -------
 4 files changed, 2 insertions(+), 106 deletions(-)

diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
index 099be8dd1900..b020a6489c07 100644
--- a/drivers/bus/mhi/host/init.c
+++ b/drivers/bus/mhi/host/init.c
@@ -841,18 +841,8 @@ static int parse_ch_cfg(struct mhi_controller *mhi_cntrl,
 		mhi_chan->lpm_notify = ch_cfg->lpm_notify;
 		mhi_chan->offload_ch = ch_cfg->offload_channel;
 		mhi_chan->db_cfg.reset_req = ch_cfg->doorbell_mode_switch;
-		mhi_chan->pre_alloc = ch_cfg->auto_queue;
 		mhi_chan->wake_capable = ch_cfg->wake_capable;
 
-		/*
-		 * If MHI host allocates buffers, then the channel direction
-		 * should be DMA_FROM_DEVICE
-		 */
-		if (mhi_chan->pre_alloc && mhi_chan->dir != DMA_FROM_DEVICE) {
-			dev_err(dev, "Invalid channel configuration\n");
-			goto error_chan_cfg;
-		}
-
 		/*
 		 * Bi-directional and direction less channel must be an
 		 * offload channel
diff --git a/drivers/bus/mhi/host/internal.h b/drivers/bus/mhi/host/internal.h
index 7937bb1f742c..7b0ee5e3a12d 100644
--- a/drivers/bus/mhi/host/internal.h
+++ b/drivers/bus/mhi/host/internal.h
@@ -286,7 +286,6 @@ struct mhi_chan {
 	bool lpm_notify;
 	bool configured;
 	bool offload_ch;
-	bool pre_alloc;
 	bool wake_capable;
 };
 
@@ -389,8 +388,6 @@ int mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
 		      struct image_info *img_info);
 void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl);
 
-/* Automatically allocate and queue inbound buffers */
-#define MHI_CH_INBOUND_ALLOC_BUFS BIT(0)
 int mhi_init_chan_ctxt(struct mhi_controller *mhi_cntrl,
 		       struct mhi_chan *mhi_chan);
 void mhi_deinit_chan_ctxt(struct mhi_controller *mhi_cntrl,
diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 861551274319..53c0ffe30070 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -664,23 +664,6 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl,
 				mhi_cntrl->runtime_put(mhi_cntrl);
 			}
 
-			/*
-			 * Recycle the buffer if buffer is pre-allocated,
-			 * if there is an error, not much we can do apart
-			 * from dropping the packet
-			 */
-			if (mhi_chan->pre_alloc) {
-				if (mhi_queue_buf(mhi_chan->mhi_dev,
-						  mhi_chan->dir,
-						  buf_info->cb_buf,
-						  buf_info->len, MHI_EOT)) {
-					dev_err(dev,
-						"Error recycling buffer for chan:%d\n",
-						mhi_chan->chan);
-					kfree(buf_info->cb_buf);
-				}
-			}
-
 			read_lock_bh(&mhi_chan->lock);
 		}
 		break;
@@ -1177,17 +1160,12 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
 int mhi_queue_skb(struct mhi_device *mhi_dev, enum dma_data_direction dir,
 		  struct sk_buff *skb, size_t len, enum mhi_flags mflags)
 {
-	struct mhi_chan *mhi_chan = (dir == DMA_TO_DEVICE) ? mhi_dev->ul_chan :
-							     mhi_dev->dl_chan;
 	struct mhi_buf_info buf_info = { };
 
 	buf_info.v_addr = skb->data;
 	buf_info.cb_buf = skb;
 	buf_info.len = len;
 
-	if (unlikely(mhi_chan->pre_alloc))
-		return -EINVAL;
-
 	return mhi_queue(mhi_dev, &buf_info, dir, mflags);
 }
 EXPORT_SYMBOL_GPL(mhi_queue_skb);
@@ -1472,45 +1450,6 @@ static int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
 	if (ret)
 		goto error_pm_state;
 
-	if (mhi_chan->dir == DMA_FROM_DEVICE)
-		mhi_chan->pre_alloc = !!(flags & MHI_CH_INBOUND_ALLOC_BUFS);
-
-	/* Pre-allocate buffer for xfer ring */
-	if (mhi_chan->pre_alloc) {
-		int nr_el = get_nr_avail_ring_elements(mhi_cntrl,
-						       &mhi_chan->tre_ring);
-		size_t len = mhi_cntrl->buffer_len;
-
-		while (nr_el--) {
-			void *buf;
-			struct mhi_buf_info info = { };
-
-			buf = kmalloc(len, GFP_KERNEL);
-			if (!buf) {
-				ret = -ENOMEM;
-				goto error_pre_alloc;
-			}
-
-			/* Prepare transfer descriptors */
-			info.v_addr = buf;
-			info.cb_buf = buf;
-			info.len = len;
-			ret = mhi_gen_tre(mhi_cntrl, mhi_chan, &info, MHI_EOT);
-			if (ret) {
-				kfree(buf);
-				goto error_pre_alloc;
-			}
-		}
-
-		read_lock_bh(&mhi_cntrl->pm_lock);
-		if (MHI_DB_ACCESS_VALID(mhi_cntrl)) {
-			read_lock_irq(&mhi_chan->lock);
-			mhi_ring_chan_db(mhi_cntrl, mhi_chan);
-			read_unlock_irq(&mhi_chan->lock);
-		}
-		read_unlock_bh(&mhi_cntrl->pm_lock);
-	}
-
 	mutex_unlock(&mhi_chan->mutex);
 
 	return 0;
@@ -1522,12 +1461,6 @@ static int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
 error_init_chan:
 	mutex_unlock(&mhi_chan->mutex);
 
-	return ret;
-
-error_pre_alloc:
-	mutex_unlock(&mhi_chan->mutex);
-	mhi_unprepare_channel(mhi_cntrl, mhi_chan);
-
 	return ret;
 }
 
@@ -1600,12 +1533,8 @@ static void mhi_reset_data_chan(struct mhi_controller *mhi_cntrl,
 		mhi_del_ring_element(mhi_cntrl, buf_ring);
 		mhi_del_ring_element(mhi_cntrl, tre_ring);
 
-		if (mhi_chan->pre_alloc) {
-			kfree(buf_info->cb_buf);
-		} else {
-			result.buf_addr = buf_info->cb_buf;
-			mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
-		}
+		result.buf_addr = buf_info->cb_buf;
+		mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
 	}
 }
 
@@ -1666,12 +1595,6 @@ int mhi_prepare_for_transfer(struct mhi_device *mhi_dev)
 }
 EXPORT_SYMBOL_GPL(mhi_prepare_for_transfer);
 
-int mhi_prepare_for_transfer_autoqueue(struct mhi_device *mhi_dev)
-{
-	return __mhi_prepare_for_transfer(mhi_dev, MHI_CH_INBOUND_ALLOC_BUFS);
-}
-EXPORT_SYMBOL_GPL(mhi_prepare_for_transfer_autoqueue);
-
 void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev)
 {
 	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index dd372b0123a6..88ccb3e14f48 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -215,7 +215,6 @@ enum mhi_db_brst_mode {
  * @lpm_notify: The channel master requires low power mode notifications
  * @offload_channel: The client manages the channel completely
  * @doorbell_mode_switch: Channel switches to doorbell mode on M0 transition
- * @auto_queue: Framework will automatically queue buffers for DL traffic
  * @wake-capable: Channel capable of waking up the system
  */
 struct mhi_channel_config {
@@ -232,7 +231,6 @@ struct mhi_channel_config {
 	bool lpm_notify;
 	bool offload_channel;
 	bool doorbell_mode_switch;
-	bool auto_queue;
 	bool wake_capable;
 };
 
@@ -743,18 +741,6 @@ void mhi_device_put(struct mhi_device *mhi_dev);
  */
 int mhi_prepare_for_transfer(struct mhi_device *mhi_dev);
 
-/**
- * mhi_prepare_for_transfer_autoqueue - Setup UL and DL channels with auto queue
- *                                      buffers for DL traffic
- * @mhi_dev: Device associated with the channels
- *
- * Allocate and initialize the channel context and also issue the START channel
- * command to both channels. Channels can be started only if both host and
- * device execution environments match and channels are in a DISABLED state.
- * The MHI core will automatically allocate and queue buffers for the DL traffic.
- */
-int mhi_prepare_for_transfer_autoqueue(struct mhi_device *mhi_dev);
-
 /**
  * mhi_unprepare_from_transfer - Reset UL and DL channels for data transfer.
  *                               Issue the RESET channel command and let the

-- 
2.48.1

Re: [PATCH v2 1/2] net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels

[Loic Poulain]

On Thu, Dec 18, 2025 at 5:51 PM Manivannan Sadhasivam via B4 Relay
<devnull+manivannan.sadhasivam.oss.qualcomm.com@kernel.org> wrote:
>
> From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
>
> MHI stack offers the 'auto_queue' feature, which allows the MHI stack to
> auto queue the buffers for the RX path (DL channel). Though this feature
> simplifies the client driver design, it introduces race between the client
> drivers and the MHI stack. For instance, with auto_queue, the 'dl_callback'
> for the DL channel may get called before the client driver is fully probed.
> This means, by the time the dl_callback gets called, the client driver's
> structures might not be initialized, leading to NULL ptr dereference.
>
> Currently, the drivers have to workaround this issue by initializing the
> internal structures before calling mhi_prepare_for_transfer_autoqueue().
> But even so, there is a chance that the client driver's internal code path
> may call the MHI queue APIs before mhi_prepare_for_transfer_autoqueue() is
> called, leading to similar NULL ptr dereference. This issue has been
> reported on the Qcom X1E80100 CRD machines affecting boot.
>
> So to properly fix all these races, drop the MHI 'auto_queue' feature
> altogether and let the client driver (QRTR) manage the RX buffers manually.
> In the QRTR driver, queue the RX buffers based on the ring length during
> probe and recycle the buffers in 'dl_callback' once they are consumed. This
> also warrants removing the setting of 'auto_queue' flag from controller
> drivers.
>
> Currently, this 'auto_queue' feature is only enabled for IPCR DL channel.
> So only the QRTR client driver requires the modification.
>
> Fixes: 227fee5fc99e ("bus: mhi: core: Add an API for auto queueing buffers for DL channel")
> Fixes: 68a838b84eff ("net: qrtr: start MHI channel after endpoit creation")
> Reported-by: Johan Hovold <johan@kernel.org>
> Closes: https://lore.kernel.org/linux-arm-msm/ZyTtVdkCCES0lkl4@hovoldconsulting.com
> Suggested-by: Chris Lew <quic_clew@quicinc.com>
> Acked-by: Jeff Johnson <jjohnson@kernel.org> # drivers/net/wireless/ath/...
> Cc: stable@vger.kernel.org
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>

Re: [PATCH v2 1/2] net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels

[Paolo Abeni]

On 12/18/25 5:51 PM, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> 
> MHI stack offers the 'auto_queue' feature, which allows the MHI stack to
> auto queue the buffers for the RX path (DL channel). Though this feature
> simplifies the client driver design, it introduces race between the client
> drivers and the MHI stack. For instance, with auto_queue, the 'dl_callback'
> for the DL channel may get called before the client driver is fully probed.
> This means, by the time the dl_callback gets called, the client driver's
> structures might not be initialized, leading to NULL ptr dereference.
> 
> Currently, the drivers have to workaround this issue by initializing the
> internal structures before calling mhi_prepare_for_transfer_autoqueue().
> But even so, there is a chance that the client driver's internal code path
> may call the MHI queue APIs before mhi_prepare_for_transfer_autoqueue() is
> called, leading to similar NULL ptr dereference. This issue has been
> reported on the Qcom X1E80100 CRD machines affecting boot.
> 
> So to properly fix all these races, drop the MHI 'auto_queue' feature
> altogether and let the client driver (QRTR) manage the RX buffers manually.
> In the QRTR driver, queue the RX buffers based on the ring length during
> probe and recycle the buffers in 'dl_callback' once they are consumed. This
> also warrants removing the setting of 'auto_queue' flag from controller
> drivers.
> 
> Currently, this 'auto_queue' feature is only enabled for IPCR DL channel.
> So only the QRTR client driver requires the modification.
> 
> Fixes: 227fee5fc99e ("bus: mhi: core: Add an API for auto queueing buffers for DL channel")
> Fixes: 68a838b84eff ("net: qrtr: start MHI channel after endpoit creation")
> Reported-by: Johan Hovold <johan@kernel.org>
> Closes: https://lore.kernel.org/linux-arm-msm/ZyTtVdkCCES0lkl4@hovoldconsulting.com
> Suggested-by: Chris Lew <quic_clew@quicinc.com>
> Acked-by: Jeff Johnson <jjohnson@kernel.org> # drivers/net/wireless/ath/...
> Cc: stable@vger.kernel.org
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

For net/...

Acked-by: Paolo Abeni <pabeni@redhat.com>

even if I don't see anything network specific there.

/P

Re: [PATCH v2 1/2] net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels

[Jeff Hugo]

On 12/18/2025 9:51 AM, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> 
> MHI stack offers the 'auto_queue' feature, which allows the MHI stack to
> auto queue the buffers for the RX path (DL channel). Though this feature
> simplifies the client driver design, it introduces race between the client
> drivers and the MHI stack. For instance, with auto_queue, the 'dl_callback'
> for the DL channel may get called before the client driver is fully probed.
> This means, by the time the dl_callback gets called, the client driver's
> structures might not be initialized, leading to NULL ptr dereference.
> 
> Currently, the drivers have to workaround this issue by initializing the
> internal structures before calling mhi_prepare_for_transfer_autoqueue().
> But even so, there is a chance that the client driver's internal code path
> may call the MHI queue APIs before mhi_prepare_for_transfer_autoqueue() is
> called, leading to similar NULL ptr dereference. This issue has been
> reported on the Qcom X1E80100 CRD machines affecting boot.
> 
> So to properly fix all these races, drop the MHI 'auto_queue' feature
> altogether and let the client driver (QRTR) manage the RX buffers manually.
> In the QRTR driver, queue the RX buffers based on the ring length during
> probe and recycle the buffers in 'dl_callback' once they are consumed. This
> also warrants removing the setting of 'auto_queue' flag from controller
> drivers.
> 
> Currently, this 'auto_queue' feature is only enabled for IPCR DL channel.
> So only the QRTR client driver requires the modification.
> 
> Fixes: 227fee5fc99e ("bus: mhi: core: Add an API for auto queueing buffers for DL channel")
> Fixes: 68a838b84eff ("net: qrtr: start MHI channel after endpoit creation")
> Reported-by: Johan Hovold <johan@kernel.org>
> Closes: https://lore.kernel.org/linux-arm-msm/ZyTtVdkCCES0lkl4@hovoldconsulting.com
> Suggested-by: Chris Lew <quic_clew@quicinc.com>
> Acked-by: Jeff Johnson <jjohnson@kernel.org> # drivers/net/wireless/ath/...
> Cc: stable@vger.kernel.org
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Reviewed-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>

For the qaic bits

Acked-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>

Re: [PATCH v2 2/2] bus: mhi: host: Drop the auto_queue support

[Jeff Hugo]

On 12/18/2025 9:51 AM, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> 
> Now that the only user of the 'auto_queue' feature, (QRTR) has been
> converted to manage the buffers on its own, drop the code related to it.
> 
> Reviewed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Reviewed-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>

Re: [PATCH v2 0/2] net: qrtr: Drop the MHI 'auto_queue' feature

[Manivannan Sadhasivam]

On Thu, 18 Dec 2025 22:21:43 +0530, Manivannan Sadhasivam wrote:
> This series intends to fix the race between the MHI stack and the MHI client
> drivers due to the MHI 'auto_queue' feature. As it turns out often, the best
> way to fix an issue in a feature is to drop the feature itself and this series
> does exactly that.
> 
> There is no real benefit in having the 'auto_queue' feature in the MHI stack,
> other than saving a few lines of code in the client drivers. Since the QRTR is
> the only client driver which makes use of this feature, this series reworks the
> QRTR driver to manage the buffer on its own.
> 
> [...]

Applied, thanks!

[1/2] net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels
      commit: 51731792a25cb312ca94cdccfa139eb46de1b2ef
[2/2] bus: mhi: host: Drop the auto_queue support
      commit: 4a9ba211d0264131dcfca0cbc10bff5ff277ff0a

Best regards,
-- 
Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Re: [PATCH v2 1/2] net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels

[Abel Vesa]

On 25-12-18 22:21:44, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> 
> MHI stack offers the 'auto_queue' feature, which allows the MHI stack to
> auto queue the buffers for the RX path (DL channel). Though this feature
> simplifies the client driver design, it introduces race between the client
> drivers and the MHI stack. For instance, with auto_queue, the 'dl_callback'
> for the DL channel may get called before the client driver is fully probed.
> This means, by the time the dl_callback gets called, the client driver's
> structures might not be initialized, leading to NULL ptr dereference.
> 
> Currently, the drivers have to workaround this issue by initializing the
> internal structures before calling mhi_prepare_for_transfer_autoqueue().
> But even so, there is a chance that the client driver's internal code path
> may call the MHI queue APIs before mhi_prepare_for_transfer_autoqueue() is
> called, leading to similar NULL ptr dereference. This issue has been
> reported on the Qcom X1E80100 CRD machines affecting boot.
> 
> So to properly fix all these races, drop the MHI 'auto_queue' feature
> altogether and let the client driver (QRTR) manage the RX buffers manually.
> In the QRTR driver, queue the RX buffers based on the ring length during
> probe and recycle the buffers in 'dl_callback' once they are consumed. This
> also warrants removing the setting of 'auto_queue' flag from controller
> drivers.
> 
> Currently, this 'auto_queue' feature is only enabled for IPCR DL channel.
> So only the QRTR client driver requires the modification.
> 
> Fixes: 227fee5fc99e ("bus: mhi: core: Add an API for auto queueing buffers for DL channel")
> Fixes: 68a838b84eff ("net: qrtr: start MHI channel after endpoit creation")
> Reported-by: Johan Hovold <johan@kernel.org>
> Closes: https://lore.kernel.org/linux-arm-msm/ZyTtVdkCCES0lkl4@hovoldconsulting.com
> Suggested-by: Chris Lew <quic_clew@quicinc.com>
> Acked-by: Jeff Johnson <jjohnson@kernel.org> # drivers/net/wireless/ath/...
> Cc: stable@vger.kernel.org
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Tested on Dell XPS13 9345, so:

Tested-by: Abel Vesa <abel.vesa@oss.qualcomm.com>