[PATCH v2 0/2] mmc: core: Add a host capability to skip SLEEP for cards with a broken resume

[PATCH v2 0/2] mmc: core: Add a host capability to skip SLEEP for cards with a broken resume

[Kamal Dasu]

This is v2 of Florian's original patch:

  Link: https://lore.kernel.org/r/20260413180551.3683969-1-florian.fainelli@broadcom.com/

Background: the Kioxia 016G01 eMMC takes ~10ms to exit SLEEP (CMD5)
instead of the ~1ms it advertises via S_A_TIMEOUT, which can be
problematic on systems that resume from Suspend-to-DRAM by first
pulling boot code from eMMC using hard wired logic that is not field
updatable -- if the card is still asleep when that logic reads it, it
resets the board. The device stays powered throughout suspend-to-
DRAM (no software-controlled VCC/VCCQ regulator toggling on this
path), and the CMD0-before-resume sequence follows the JEDEC boot
spec, so this isn't something the kernel's resume ordering can fix
on its own.

v1 addressed this with a card-level MMC_QUIRK_BROKEN_SLEEP quirk
keyed off the device CID. Ulf pointed out that a device-specific
quirk doesn't generalize well and suggested a host capability bit
instead, settable from DT (or derived from a compatible string),
mirroring the existing no-sdio/no-sd/no-mmc properties. Oleksij
separately noted that quirks registered in mmc_blk_fixups[] are only
applied once the mmc_block driver probes, which is too late to avoid
a race against an earlier SLEEP/poweroff triggered on an under-
voltage path -- a host cap resolved in mmc_of_parse(), before any
card exists, sidesteps that ordering problem entirely.

This series implements that direction:

  - Patch 1 documents a new "no-mmc-sleep" DT flag property.
  - Patch 2 adds MMC_CAP2_NO_SLEEP_CMD, parses the DT property in
    mmc_of_parse(), and has mmc_card_can_sleep() honor it.

The actual board DT change (adding "no-mmc-sleep;" to the affected
brcmstb eMMC controller node) will follow separately once this lands,
since that DT lives outside of mainline.

Changes in v2:
  - Dropped the card-quirk/CID-match approach entirely in favor of a
    host capability bit, per Ulf's suggestion.
  - Added a DT property ("no-mmc-sleep") to set that capability,
    following the no-sdio/no-sd/no-mmc precedent, per Ulf.
  - This also resolves Oleksij's concern about mmc_blk_fixups[]
    being applied too late to close the race on an early
    SLEEP/poweroff path, since the host cap is resolved in
    mmc_of_parse() before a card exists.
  - Reworded the rationale in patch 1's commit message and binding
    description per Florian's review.
  - Added a Reported-by/Closes tag crediting Florian for the
    original bug report.

Kamal Dasu (2):
  dt-bindings: mmc: Document no-mmc-sleep property
  mmc: core: Add MMC_CAP2_NO_SLEEP_CMD host capability

 .../devicetree/bindings/mmc/mmc-controller-common.yaml    | 8 ++++++++
 drivers/mmc/core/host.c                                   | 2 ++
 drivers/mmc/core/mmc.c                                    | 3 +++
 include/linux/mmc/host.h                                  | 1 +
 4 files changed, 14 insertions(+)

-- 
2.34.1

[PATCH v2 1/2] dt-bindings: mmc: Document no-mmc-sleep property

[Kamal Dasu]

Some (e)MMC devices cannot reliably resume from the SLEEP (CMD5)
state within their advertised S_A_TIMEOUT, which can be problematic
on systems that resume from Suspend-to-DRAM by first pulling boot
code from eMMC using hard wired logic that is not field updatable.
Add a no-mmc-sleep flag property so affected boards can tell the
mmc core to never put the card to sleep.

Signed-off-by: Kamal Dasu <kamal.dasu@broadcom.com>
---
Changes in v2:
  - New patch. v1 used a card-level MMC_QUIRK_BROKEN_SLEEP quirk
    instead of a DT property; this documents the DT property backing
    the host capability added in patch 2, per Ulf's suggestion.
  - Reworded the rationale in the commit message and the binding
    description per Florian's review.

 .../devicetree/bindings/mmc/mmc-controller-common.yaml    | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml b/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml
index 3d7195e9461c..11df0524530c 100644
--- a/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml
+++ b/Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml
@@ -232,6 +232,14 @@ properties:
     description:
       All eMMC HS400 modes are not supported.
 
+  no-mmc-sleep:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      The attached (e)MMC card cannot reliably resume from the SLEEP
+      (CMD5) state within its advertised S_A_TIMEOUT, so the
+      controller must not put it to sleep during suspend or power
+      off.
+
   dsr:
     description:
       Value the card Driver Stage Register (DSR) should be programmed
-- 
2.34.1

[PATCH v2 2/2] mmc: core: Add MMC_CAP2_NO_SLEEP_CMD host capability

[Kamal Dasu]

Some (e)MMC devices take longer to exit the SLEEP (CMD5) state than
their advertised S_A_TIMEOUT allows for. On platforms where a boot
ROM sends CMD0 and reads boot code from the card immediately on
resume, a card still asleep at that point causes the ROM to treat
it as fatal and reset.

Add MMC_CAP2_NO_SLEEP_CMD, settable via the new "no-mmc-sleep" DT
property, so affected hosts can tell mmc_card_can_sleep() to never
put the card to sleep, regardless of ext_csd revision. This is a
host-level capability rather than a card quirk so it also covers
cards whose bug can't be identified by CID/ext_csd matching alone,
and it is resolved before the card even exists, avoiding any
ordering dependency on when a card-quirk table would be applied.

Reported-by: Florian Fainelli <florian.fainelli@broadcom.com>
Closes: https://lore.kernel.org/r/20260413180551.3683969-1-florian.fainelli@broadcom.com/
Signed-off-by: Kamal Dasu <kamal.dasu@broadcom.com>
---
Changes in v2:
  - Replaced the card-level MMC_QUIRK_BROKEN_SLEEP quirk (keyed off
    CID) with a host capability, MMC_CAP2_NO_SLEEP_CMD, set from the
    new "no-mmc-sleep" DT property, per Ulf's suggestion that this
    generalize beyond one device's CID.
  - Resolving the capability in mmc_of_parse(), before any card
    exists, also addresses Oleksij's concern that a quirk registered
    in mmc_blk_fixups[] (applied at mmc_block probe time) could lose
    a race against an earlier SLEEP/poweroff on an under-voltage
    path.
  - Added Reported-by/Closes tags crediting Florian for the original
    bug report.

 drivers/mmc/core/host.c  | 2 ++
 drivers/mmc/core/mmc.c   | 3 +++
 include/linux/mmc/host.h | 1 +
 3 files changed, 6 insertions(+)

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index b7ce3137d452..3bc19645ea96 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -400,6 +400,8 @@ int mmc_of_parse(struct mmc_host *host)
 	if (device_property_read_bool(dev, "no-mmc-hs400"))
 		host->caps2 &= ~(MMC_CAP2_HS400_1_8V | MMC_CAP2_HS400_1_2V |
 				 MMC_CAP2_HS400_ES);
+	if (device_property_read_bool(dev, "no-mmc-sleep"))
+		host->caps2 |= MMC_CAP2_NO_SLEEP_CMD;
 
 	/* Must be after "non-removable" check */
 	if (device_property_read_u32(dev, "fixed-emmc-driver-type", &drv_type) == 0) {
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 05444ecf3909..5e80fa5c1a28 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1972,6 +1972,9 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
 
 static bool mmc_card_can_sleep(struct mmc_card *card)
 {
+	if (card->host->caps2 & MMC_CAP2_NO_SLEEP_CMD)
+		return false;
+
 	return card->ext_csd.rev >= 3;
 }
 
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index ba84f02c2a10..0447a8efed50 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -463,6 +463,7 @@ struct mmc_host {
 #define MMC_CAP2_CRYPTO		0
 #endif
 #define MMC_CAP2_ALT_GPT_TEGRA	(1 << 28)	/* Host with eMMC that has GPT entry at a non-standard location */
+#define MMC_CAP2_NO_SLEEP_CMD	(1 << 29)	/* Card can't reliably wake from CMD5 SLEEP */
 
 	bool			uhs2_sd_tran;	/* UHS-II flag for SD_TRAN state */
 	bool			uhs2_app_cmd;	/* UHS-II flag for APP command */
-- 
2.34.1