Re: [PATCH v2] mmc: Add quirk MMC_QUIRK_BROKEN_CACHE_FLUSH for Micron eMMC Q2J54A

On Thu, 14 Sept 2023 at 22:28, Bean Huo beanhuo@iokpp.de wrote:

From: Bean Huo beanhuo@micron.com

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.

For my information, more exactly, how can we trigger this problem?

Signed-off-by: Bean Huo beanhuo@micron.com Co-developed-by: Rafael Beims rafael.beims@toradex.com Tested-by: Rafael Beims rafael.beims@toradex.com Cc: stable@vger.kernel.org

---

Changelog:

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/core.c | 7 +++++++ drivers/mmc/core/mmc.c | 5 +++++ drivers/mmc/core/quirks.h | 7 ++++--- include/linux/mmc/card.h | 2 ++ 4 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 3d3e0ca52614..86a669b35b91 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -259,6 +259,13 @@ static void __mmc_start_request(struct mmc_host *host, struct mmc_request *mrq) host->cqe_ops->cqe_off(host);

    host->ops->request(host, mrq);

•   if (host->card && host->card->quirks & MMC_QUIRK_BROKEN_CACHE_FLUSH &&
  

•       !host->card->written_flag) {
  

•           if (mrq->cmd->opcode == MMC_WRITE_MULTIPLE_BLOCK ||
  

•               mrq->cmd->opcode == MMC_WRITE_BLOCK)
  

•                   host->card->written_flag = true;
  

•   }
  

I don't quite like that we are adding the above code here - as it's used for *all* requests.

Seems like the flag is better set from the mmc block device driver instead. Somewhere in the path when we serve I/O write requests.

}

static void mmc_mrq_pr_debug(struct mmc_host *host, struct mmc_request *mrq, diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 89cd48fcec79..a2edd065fa1b 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;
  

According to your earlier reply, it sounds like the problem isn't really about the card being re-initialized, but rather that we actually need a write request to happen before a flush. No matter what, no?

See more about this below.

    return 0;

free_card: @@ -2081,6 +2083,9 @@ static int _mmc_flush_cache(struct mmc_host *host) { int err = 0;

•   if (host->card->quirks & MMC_QUIRK_BROKEN_CACHE_FLUSH && !host->card->written_flag)
  

•           return err;
  

Could an option to the above, be to reset the flag here instead. After a successful cache flush has been done.

    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 */
  

-- 2.34.1

Kind regards Uffe