[PATCH v3 0/2] ufs: qcom: Fix probe failure on SM8550 SoC due to broken LSDBS field

[PATCH v3 0/2] ufs: qcom: Fix probe failure on SM8550 SoC due to broken LSDBS field

[Manivannan Sadhasivam via B4 Relay]

Hi,

This series fixes the probe failure on the Qcom SM8550 SoC due to the broken
LSDBS field in the host controller capabilities register.

Please consider this series for v6.11 as it fixes a regression.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
Changes in v3:
- Dropped the patch that renamed LSDB field
- Changed the comment for the quirk and also fixed the UFSHCI version in
  description
- Collected review tag
- Link to v2: https://lore.kernel.org/r/20240815-ufs-bug-fix-v2-0-b373afae888f@linaro.org

Changes in v2:
- Changed SDBS to LSDBS as per the final version of UFSHCI 4.0 spec
- Moved the quirk check to assignment
- Used correct fixes tag in patch 3/3
- Added tested-by tags
- Link to v1: https://lore.kernel.org/r/20240814-ufs-bug-fix-v1-0-5eb49d5f7571@linaro.org

---
Manivannan Sadhasivam (2):
      ufs: core: Add a quirk for handling broken LSDBS field in controller capabilities register
      ufs: qcom: Add UFSHCD_QUIRK_BROKEN_LSDBS_CAP for SM8550 SoC

 drivers/ufs/core/ufshcd.c   | 6 +++++-
 drivers/ufs/host/ufs-qcom.c | 6 +++++-
 include/ufs/ufshcd.h        | 8 ++++++++
 3 files changed, 18 insertions(+), 2 deletions(-)
---
base-commit: 7c626ce4bae1ac14f60076d00eafe71af30450ba
change-id: 20240814-ufs-bug-fix-4427fb01b860

Best regards,
-- 
Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

[PATCH v3 1/2] ufs: core: Add a quirk for handling broken LSDBS field in controller capabilities register

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

'Legacy Queue & Single Doorbell Support (LSDBS)' field in the controller
capabilities register is supposed to report whether the legacy single
doorbell mode is supported in the controller or not. But some controllers
report '1' in this field which corresponds to 'LSDB not supported', but
they indeed support LSDB. So let's add a quirk to handle those controllers.

If the quirk is enabled by the controller driver, then LSDBS register field
will be ignored and legacy single doorbell mode is assumed to be enabled
always.

Tested-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/ufs/core/ufshcd.c | 6 +++++-
 include/ufs/ufshcd.h      | 8 ++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 0b3d0c8e0dda..a6f818cdef0e 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2426,7 +2426,11 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba)
 	 * 0h: legacy single doorbell support is available
 	 * 1h: indicate that legacy single doorbell support has been removed
 	 */
-	hba->lsdb_sup = !FIELD_GET(MASK_LSDB_SUPPORT, hba->capabilities);
+	if (!(hba->quirks & UFSHCD_QUIRK_BROKEN_LSDBS_CAP))
+		hba->lsdb_sup = !FIELD_GET(MASK_LSDB_SUPPORT, hba->capabilities);
+	else
+		hba->lsdb_sup = true;
+
 	if (!hba->mcq_sup)
 		return 0;
 
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index cac0cdb9a916..0fd2aebac728 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -676,6 +676,14 @@ enum ufshcd_quirks {
 	 * the standard best practice for managing keys).
 	 */
 	UFSHCD_QUIRK_KEYS_IN_PRDT			= 1 << 24,
+
+	/*
+	 * This quirk indicates that the controller reports the value 1 (not
+	 * supported) in the Legacy Single DoorBell Support (LSDBS) bit of the
+	 * Controller Capabilities register although it supports the legacy
+	 * single doorbell mode.
+	 */
+	UFSHCD_QUIRK_BROKEN_LSDBS_CAP			= 1 << 25,
 };
 
 enum ufshcd_caps {

-- 
2.25.1

[PATCH v3 2/2] ufs: qcom: Add UFSHCD_QUIRK_BROKEN_LSDBS_CAP for SM8550 SoC

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

SM8550 SoC has the UFSHCI 4.0 compliant UFS controller and only supports
legacy single doorbell mode without MCQ. But due to a hardware bug, it
reports 1 in the 'Legacy Queue & Single Doorbell Support (LSDBS)' field of
the Controller Capabilities register. This field is supposed to read as 0
if legacy single doorbell mode is supported and 1 otherwise.

Starting with commit 0c60eb0cc320 ("scsi: ufs: core: Check LSDBS cap when
!mcq"), ufshcd driver is now relying on the LSDBS field to decide when to
use the legacy doorbell mode if MCQ is not supported. And this ends up
breaking UFS on SM8550:

ufshcd-qcom 1d84000.ufs: ufshcd_init: failed to initialize (legacy doorbell mode not supported)
ufshcd-qcom 1d84000.ufs: error -EINVAL: Initialization failed with error -22

So use the UFSHCD_QUIRK_BROKEN_LSDBS_CAP quirk for SM8550 SoC so that the
ufshcd driver could use legacy doorbell mode correctly.

Fixes: 0c60eb0cc320 ("scsi: ufs: core: Check LSDBS cap when !mcq")
Tested-by: Amit Pundir <amit.pundir@linaro.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/ufs/host/ufs-qcom.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
index 810e637047d0..c87fdc849c62 100644
--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -857,6 +857,9 @@ static void ufs_qcom_advertise_quirks(struct ufs_hba *hba)
 
 	if (host->hw_ver.major > 0x3)
 		hba->quirks |= UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH;
+
+	if (of_device_is_compatible(hba->dev->of_node, "qcom,sm8550-ufshc"))
+		hba->quirks |= UFSHCD_QUIRK_BROKEN_LSDBS_CAP;
 }
 
 static void ufs_qcom_set_phy_gear(struct ufs_qcom_host *host)
@@ -1847,7 +1850,8 @@ static void ufs_qcom_remove(struct platform_device *pdev)
 }
 
 static const struct of_device_id ufs_qcom_of_match[] __maybe_unused = {
-	{ .compatible = "qcom,ufshc"},
+	{ .compatible = "qcom,ufshc" },
+	{ .compatible = "qcom,sm8550-ufshc" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, ufs_qcom_of_match);

-- 
2.25.1

Re: [PATCH v3 1/2] ufs: core: Add a quirk for handling broken LSDBS field in controller capabilities register

[Bart Van Assche]

On 8/15/24 11:25 PM, Manivannan Sadhasivam via B4 Relay wrote:
> 'Legacy Queue & Single Doorbell Support (LSDBS)' field in the controller
> capabilities register is supposed to report whether the legacy single
> doorbell mode is supported in the controller or not. But some controllers
> report '1' in this field which corresponds to 'LSDB not supported', but
> they indeed support LSDB. So let's add a quirk to handle those controllers.
> 
> If the quirk is enabled by the controller driver, then LSDBS register field
> will be ignored and legacy single doorbell mode is assumed to be enabled
> always.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Re: [PATCH v3 0/2] ufs: qcom: Fix probe failure on SM8550 SoC due to broken LSDBS field

[Martin K. Petersen]

On Fri, 16 Aug 2024 11:55:09 +0530, Manivannan Sadhasivam wrote:

> This series fixes the probe failure on the Qcom SM8550 SoC due to the broken
> LSDBS field in the host controller capabilities register.
> 
> Please consider this series for v6.11 as it fixes a regression.
> 
> 

Applied to 6.11/scsi-fixes, thanks!

[1/2] ufs: core: Add a quirk for handling broken LSDBS field in controller capabilities register
      https://git.kernel.org/mkp/scsi/c/cd06b713a688
[2/2] ufs: qcom: Add UFSHCD_QUIRK_BROKEN_LSDBS_CAP for SM8550 SoC
      https://git.kernel.org/mkp/scsi/c/ea593e028a9c

-- 
Martin K. Petersen	Oracle Linux Engineering