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From: "Christian Löhle" <CLoehle@hyperstone.com>
To: "jh80.chung@samsung.com" <jh80.chung@samsung.com>,
	"ulf.hansson@linaro.org" <ulf.hansson@linaro.org>,
	"Christian Löhle" <CLoehle@hyperstone.com>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [PATCH] mmc: dw_mmc: Dont wait for DRTO on Write RSP error
Date: Thu, 16 Sep 2021 05:59:19 +0000	[thread overview]
Message-ID: <af8f8b8674ba4fcc9a781019e4aeb72c@hyperstone.com> (raw)

Only wait for DRTO on reads, otherwise the driver hangs.

The driver prevents sending CMD12 on response errors like CRCs.
According to the comment this is because some cards have problems
with this during the UHS tuning sequence.
Unfortunately this workaround currently also applies for any command
with data.
On reads this will set the drto timer which then triggers after a while.
On writes this will not set any timer and the tasklet will not be
scheduled again.
I cannot attest for the UHS workarounds need, but even if so, it should
at most apply to reads.
I have observed many hangs when CMD25 response contained a CRC error.
This patch fixes this without touching the actual UHS tuning workaround.

Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
---
 drivers/mmc/host/dw_mmc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 6578cc64ae9e..22cf13dc799b 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2081,7 +2081,8 @@ static void dw_mci_tasklet_func(struct tasklet_struct *t)
 				 * delayed. Allowing the transfer to take place
 				 * avoids races and keeps things simple.
 				 */
-				if (err != -ETIMEDOUT) {
+				if (err != -ETIMEDOUT &&
+				    host->dir_status == DW_MCI_RECV_STATUS) {
 					state = STATE_SENDING_DATA;
 					continue;
 				}
-- 
2.32.0
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             reply	other threads:[~2021-09-16  5:59 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20210916055929epcas1p2b5cc839886e68a2f2cec17200a2b6d83@epcas1p2.samsung.com>
2021-09-16  5:59 ` Christian Löhle [this message]
2021-09-22 22:52   ` [PATCH] mmc: dw_mmc: Dont wait for DRTO on Write RSP error Jaehoon Chung
2021-09-23  4:44     ` Jaehoon Chung
2021-09-23 18:49   ` Ulf Hansson

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