The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 77347eda64ed5c9383961d1de9165f9d0b7d8df6 Mon Sep 17 00:00:00 2001

From: Wolfram Sang wsa+renesas@sang-engineering.com Date: Thu, 24 Jun 2021 17:16:14 +0200 Subject: [PATCH] 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 yoshihiro.shimoda.uh@renesas.com Suggested-by: Adrian Hunter adrian.hunter@intel.com Signed-off-by: Wolfram Sang wsa+renesas@sang-engineering.com Acked-by: Adrian Hunter adrian.hunter@intel.com Reviewed-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com Tested-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com Fixes: bd11e8bd03ca ("mmc: core: Flag re-tuning is needed on CRC errors") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210624151616.38770-2-wsa+renesas@sang-engineerin... Signed-off-by: Ulf Hansson ulf.hansson@linaro.org

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; }