mmc: core: clear flags before allowing to retune

It might be that something goes wrong during tuning so the MMC core will
immediately trigger a retune. In our case it was:

 - we sent a tuning block
 - there was an error so we need to send an abort cmd to the eMMC
 - the abort cmd had a CRC error
 - retune was set by the MMC core

This lead to a vicious circle causing a performance regression of 75%.
So, clear retuning flags before we enable retuning to start with a known
cleared state.

Reported-by Yoshihiro Shimoda <[email protected]>
Suggested-by: Adrian Hunter <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
Acked-by: Adrian Hunter <[email protected]>
Reviewed-by: Yoshihiro Shimoda <[email protected]>
Tested-by: Yoshihiro Shimoda <[email protected]>
Fixes: bd11e8bd03ca ("mmc: core: Flag re-tuning is needed on CRC errors")
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ulf Hansson <[email protected]>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index b039dcff17f8..95fedcf56e4a 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -937,11 +937,14 @@ int mmc_execute_tuning(struct mmc_card *card)
 
 	err = host->ops->execute_tuning(host, opcode);
 
-	if (err)
+	if (err) {
 		pr_err("%s: tuning execution failed: %d\n",
 			mmc_hostname(host), err);
-	else
+	} else {
+		host->retune_now = 0;
+		host->need_retune = 0;
 		mmc_retune_enable(host);
+	}
 
 	return err;
 }