From 6c8e3e70c92fdfe2813817c401ec05f2bc6c6a9d Mon Sep 17 00:00:00 2001 From: Subhash Jadavani Date: Fri, 13 Nov 2015 12:15:53 -0800 Subject: [PATCH] mmc: block: workaround for timeout issue with some vendor devices Commit 66a7393a3ba9685d1eddfbce72e3ef8f4848f19f ("mmc: block: ensure CMDQ is empty before queuing cache flush") added a workaround for particular vendor's eMMC devices. Workaround was to wait for all the outstanding requests to finish up before queuing the flush request. Now detailed root cause analysis from vendor shows that original issue can happen only if DCMD command is sent to device too quickly (within less than 6 microseconds) after completion of previous small sector (less than 8 sectors) read operations. Hence with this change, we are fine tuning the previous workaround such that it would almost have no impact on the storage benchmark performance numbers. Change-Id: I1df1c5d7bbcd7b526236651077b7dade2626cb30 Signed-off-by: Subhash Jadavani [subhashj@codeaurora.org: fixed trivial merge conflicts] Signed-off-by: Subhash Jadavani --- drivers/mmc/card/block.c | 50 +++++++++++++++++++++++++++++----------- include/linux/mmc/card.h | 6 +++-- include/linux/mmc/host.h | 1 + 3 files changed, 41 insertions(+), 16 deletions(-) diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index 6dad4673090f..120e4577b678 100644 --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -2912,6 +2912,15 @@ static int mmc_blk_cmdq_issue_rw_rq(struct mmc_queue *mq, struct request *req) mc_rq = mmc_blk_cmdq_rw_prep(active_mqrq, mq); ret = mmc_blk_cmdq_start_req(card->host, mc_rq); + + if (!ret && (card->quirks & MMC_QUIRK_CMDQ_EMPTY_BEFORE_DCMD)) { + unsigned int sectors = blk_rq_sectors(req); + + if (((sectors > 0) && (sectors < 8)) + && (rq_data_dir(req) == READ)) + host->cmdq_ctx.active_small_sector_read_reqs++; + } + return ret; } @@ -3487,6 +3496,32 @@ static int mmc_blk_cmdq_issue_rq(struct mmc_queue *mq, struct request *req) } if (req) { + struct mmc_host *host = card->host; + struct mmc_cmdq_context_info *ctx = &host->cmdq_ctx; + + if ((cmd_flags & (REQ_FLUSH | REQ_DISCARD)) && + (card->quirks & MMC_QUIRK_CMDQ_EMPTY_BEFORE_DCMD) && + ctx->active_small_sector_read_reqs) { + ret = wait_event_interruptible(ctx->queue_empty_wq, + !ctx->active_reqs); + if (ret) { + pr_err("%s: failed while waiting for the CMDQ to be empty %s err (%d)\n", + mmc_hostname(host), + __func__, ret); + BUG_ON(1); + } + /* clear the counter now */ + ctx->active_small_sector_read_reqs = 0; + /* + * If there were small sector (less than 8 sectors) read + * operations in progress then we have to wait for the + * outstanding requests to finish and should also have + * atleast 6 microseconds delay before queuing the DCMD + * request. + */ + udelay(MMC_QUIRK_CMDQ_DELAY_BEFORE_DCMD); + } + if (cmd_flags & REQ_DISCARD) { if (cmd_flags & REQ_SECURE && !(card->quirks & MMC_QUIRK_SEC_ERASE_TRIM_BROKEN)) @@ -3494,19 +3529,6 @@ static int mmc_blk_cmdq_issue_rq(struct mmc_queue *mq, struct request *req) else ret = mmc_blk_cmdq_issue_discard_rq(mq, req); } else if (cmd_flags & REQ_FLUSH) { - if (card->quirks & - MMC_QUIRK_CMDQ_EMPTY_BEFORE_FLUSH) { - ret = wait_event_interruptible( - card->host->cmdq_ctx.queue_empty_wq, - (!card->host->cmdq_ctx.active_reqs)); - if (ret) { - pr_err("%s: failed while waiting for the CMDQ to be empty %s err (%d)\n", - mmc_hostname(card->host), - __func__, ret); - BUG_ON(1); - } - } - ret = mmc_blk_cmdq_issue_flush_rq(mq, req); } else { ret = mmc_blk_cmdq_issue_rw_rq(mq, req); @@ -3975,7 +3997,7 @@ static const struct mmc_fixup blk_fixups[] = MMC_FIXUP("MMC32G", CID_MANFID_TOSHIBA, CID_OEMID_ANY, add_quirk_mmc, MMC_QUIRK_BLK_NO_CMD23), MMC_FIXUP(CID_NAME_ANY, CID_MANFID_TOSHIBA, CID_OEMID_ANY, - add_quirk_mmc, MMC_QUIRK_CMDQ_EMPTY_BEFORE_FLUSH), + add_quirk_mmc, MMC_QUIRK_CMDQ_EMPTY_BEFORE_DCMD), /* * Some Micron MMC cards needs longer data read timeout than diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h index 2574e8af91fe..5ee1a379b82b 100644 --- a/include/linux/mmc/card.h +++ b/include/linux/mmc/card.h @@ -335,6 +335,8 @@ enum mmc_pon_type { MMC_SHRT_PON, }; +#define MMC_QUIRK_CMDQ_DELAY_BEFORE_DCMD 6 /* microseconds */ + /* * MMC device */ @@ -388,8 +390,8 @@ struct mmc_card { #define MMC_QUIRK_QCA9377_SETTINGS (1 << 16) /* QCA9377 card settings*/ -/* Make sure CMDQ is empty before queuing cache flush */ -#define MMC_QUIRK_CMDQ_EMPTY_BEFORE_FLUSH (1 << 17) +/* Make sure CMDQ is empty before queuing DCMD */ +#define MMC_QUIRK_CMDQ_EMPTY_BEFORE_DCMD (1 << 17) unsigned int erase_size; /* erase size in sectors */ unsigned int erase_shift; /* if erase unit is power 2 */ diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 959713837423..6dd6add52d64 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -260,6 +260,7 @@ struct mmc_cmdq_context_info { #define CMDQ_STATE_HALT 2 wait_queue_head_t queue_empty_wq; wait_queue_head_t wait; + int active_small_sector_read_reqs; }; /**