linux-kernel - [PATCH] mmc: Try power cycling card if command request times out

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Message-ID: <20210216224252.22187-1-marten.lindahl@axis.com>
Date:   Tue, 16 Feb 2021 23:42:52 +0100
From:   Mårten Lindahl <marten.lindahl@...s.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
CC:     <kernel@...s.com>,
        Mårten Lindahl <marten.lindahl@...s.com>,
        <linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] mmc: Try power cycling card if command request times out

Sometimes SD cards that has been run for a long time enters a state
where it cannot by itself be recovered, but needs a power cycle to be
operational again. Card status analysis has indicated that the card can
end up in a state where all external commands are ignored by the card
since it is halted by data timeouts.

If the card has been heavily used for a long time it can be weared out,
and should typically be replaced. But on some tests, it shows that the
card can still be functional after a power cycle, but as it requires an
operator to do it, the card can remain in a non-operational state for a
long time until the problem has been observed by the operator.

This patch adds function to power cycle the card in case it does not
respond to a command, and then resend the command if the power cycle
was successful. This procedure will be tested 1 time before giving up,
and resuming host operation as normal.

Signed-off-by: Mårten Lindahl <marten.lindahl@...s.com>
---
Please note: This might not be the way we want to handle these cases,
but at least it lets us start the discussion. In which cases should the
mmc framework deal with error messages like ETIMEDOUT, and in which
cases should it be handled by userspace?
The mmc framework tries to recover a failed block request
(mmc_blk_mq_rw_recovery) which may end up in a HW reset of the card.
Would it be an idea to act in a similar way when an ioctl times out?

 drivers/mmc/core/block.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 42e27a298218..d007b2af64d6 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -976,6 +976,7 @@ static inline void mmc_blk_reset_success(struct mmc_blk_data *md, int type)
  */
 static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
 {
+	int type = rq_data_dir(req) == READ ? MMC_BLK_READ : MMC_BLK_WRITE;
 	struct mmc_queue_req *mq_rq;
 	struct mmc_card *card = mq->card;
 	struct mmc_blk_data *md = mq->blkdata;
@@ -983,7 +984,7 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
 	bool rpmb_ioctl;
 	u8 **ext_csd;
 	u32 status;
-	int ret;
+	int ret, retry = 1;
 	int i;
 
 	mq_rq = req_to_mmc_queue_req(req);
@@ -994,9 +995,24 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
 	case MMC_DRV_OP_IOCTL_RPMB:
 		idata = mq_rq->drv_op_data;
 		for (i = 0, ret = 0; i < mq_rq->ioc_count; i++) {
+cmd_do:
 			ret = __mmc_blk_ioctl_cmd(card, md, idata[i]);
-			if (ret)
+			if (ret == -ETIMEDOUT) {
+				dev_warn(mmc_dev(card->host),
+					 "error %d sending command\n", ret);
+cmd_reset:
+				mmc_blk_reset_success(md, type);
+				if (retry--) {
+					dev_warn(mmc_dev(card->host),
+						 "power cycling card\n");
+					if (mmc_blk_reset
+					    (md, card->host, type))
+						goto cmd_reset;
+					mmc_blk_reset_success(md, type);
+					goto cmd_do;
+				}
 				break;
+			}
 		}
 		/* Always switch back to main area after RPMB access */
 		if (rpmb_ioctl)
-- 
2.11.0