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

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 <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]/
Signed-off-by: Kamal Dasu <[email protected]>
---
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