Re: [PATCH v4] mmc: Add quirk MMC_QUIRK_BROKEN_CACHE_FLUSH for Micron eMMC Q2J54A

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Hi Ulf,

Any comments on this version?

Kind regards,

Beam

On 01.10.23 9:49 PM, Bean Huo wrote:
From: Bean Huo <beanhuo@xxxxxxxxxx>

Micron MTFC4GACAJCN eMMC supports cache but requires that flush cache
operation be allowed only after a write has occurred. Otherwise, the
cache flush command or subsequent commands will time out.

Signed-off-by: Bean Huo <beanhuo@xxxxxxxxxx>
Signed-off-by: Rafael Beims <rafael.beims@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx

---
Changelog:

v3--v4:
     1. Add helper function for this quirk in drivers/mmc/core/card.h.
     2. Set card->written_flag only for REQ_OP_WRITE.
v2--v3:
     1. Set card->written_flag in mmc_blk_mq_issue_rq().
v1--v2:
     1. Add Rafael's test-tag, and Co-developed-by.
     2. Check host->card whether NULL or not in __mmc_start_request() before asserting host->card->->quirks
---
  drivers/mmc/core/block.c  | 5 ++++-
  drivers/mmc/core/card.h   | 4 ++++
  drivers/mmc/core/mmc.c    | 5 +++++
  drivers/mmc/core/quirks.h | 7 ++++---
  include/linux/mmc/card.h  | 2 ++
  5 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 3a8f27c3e310..dfa67d9c80bb 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -2381,8 +2381,11 @@ enum mmc_issued mmc_blk_mq_issue_rq(struct mmc_queue *mq, struct request *req)
  			}
  			ret = mmc_blk_cqe_issue_flush(mq, req);
  			break;
-		case REQ_OP_READ:
  		case REQ_OP_WRITE:
+			if (mmc_card_broken_cache_flush(card) && !card->written_flag)
+				card->written_flag = true;
+			fallthrough;
+		case REQ_OP_READ:
  			if (host->cqe_enabled)
  				ret = mmc_blk_cqe_issue_rw_rq(mq, req);
  			else
diff --git a/drivers/mmc/core/card.h b/drivers/mmc/core/card.h
index 4edf9057fa79..b7754a1b8d97 100644
--- a/drivers/mmc/core/card.h
+++ b/drivers/mmc/core/card.h
@@ -280,4 +280,8 @@ static inline int mmc_card_broken_sd_cache(const struct mmc_card *c)
  	return c->quirks & MMC_QUIRK_BROKEN_SD_CACHE;
  }
+static inline int mmc_card_broken_cache_flush(const struct mmc_card *c)
+{
+	return c->quirks & MMC_QUIRK_BROKEN_CACHE_FLUSH;
+}
  #endif
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 89cd48fcec79..47896c32086e 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1929,6 +1929,8 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
  	if (!oldcard)
  		host->card = card;
+ card->written_flag = false;
+
  	return 0;
free_card:
@@ -2081,6 +2083,9 @@ static int _mmc_flush_cache(struct mmc_host *host)
  {
  	int err = 0;
+ if (mmc_card_broken_cache_flush(host->card) && !host->card->written_flag)
+		return err;
+
  	if (_mmc_cache_enabled(host)) {
  		err = mmc_switch(host->card, EXT_CSD_CMD_SET_NORMAL,
  				 EXT_CSD_FLUSH_CACHE, 1,
diff --git a/drivers/mmc/core/quirks.h b/drivers/mmc/core/quirks.h
index 32b64b564fb1..5e68c8b4cdca 100644
--- a/drivers/mmc/core/quirks.h
+++ b/drivers/mmc/core/quirks.h
@@ -110,11 +110,12 @@ static const struct mmc_fixup __maybe_unused mmc_blk_fixups[] = {
  		  MMC_QUIRK_TRIM_BROKEN),
/*
-	 * Micron MTFC4GACAJCN-1M advertises TRIM but it does not seems to
-	 * support being used to offload WRITE_ZEROES.
+	 * Micron MTFC4GACAJCN-1M supports TRIM but does not appear to suppor
+	 * WRITE_ZEROES offloading. It also supports caching, but the cache can
+	 * only be flushed after a write has occurred.
  	 */
  	MMC_FIXUP("Q2J54A", CID_MANFID_MICRON, 0x014e, add_quirk_mmc,
-		  MMC_QUIRK_TRIM_BROKEN),
+		  MMC_QUIRK_TRIM_BROKEN | MMC_QUIRK_BROKEN_CACHE_FLUSH),
/*
  	 * Kingston EMMC04G-M627 advertises TRIM but it does not seems to
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index daa2f40d9ce6..7b12eebc5586 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -295,7 +295,9 @@ struct mmc_card {
  #define MMC_QUIRK_BROKEN_HPI	(1<<13)		/* Disable broken HPI support */
  #define MMC_QUIRK_BROKEN_SD_DISCARD	(1<<14)	/* Disable broken SD discard support */
  #define MMC_QUIRK_BROKEN_SD_CACHE	(1<<15)	/* Disable broken SD cache support */
+#define MMC_QUIRK_BROKEN_CACHE_FLUSH	(1<<16)	/* Don't flush cache until the write has occurred */
+ bool written_flag; /* Indicates eMMC has been written since power on */
  	bool			reenable_cmdq;	/* Re-enable Command Queue */
unsigned int erase_size; /* erase size in sectors */



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