The patch below does not apply to the 4.14-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 0add6e9b88d0632a25323aaf4987dbacb0e4ae64 Mon Sep 17 00:00:00 2001

From: Michael Walle michael@walle.cc Date: Fri, 23 Oct 2020 00:23:37 +0200 Subject: [PATCH] mmc: sdhci-of-esdhc: set timeout to max before tuning

On rare occations there is the following error:

mmc0: Tuning timeout, falling back to fixed sampling clock

There are SD cards which takes a significant longer time to reply to the first CMD19 command. The eSDHC takes the data timeout value into account during the tuning period. The SDHCI core doesn't explicitly set this timeout for the tuning procedure. Thus on the slow cards, there might be a spurious "Buffer Read Ready" interrupt, which in turn triggers a wrong sequence of events. In the end this will lead to an unsuccessful tuning procedure and to the above error.

To workaround this, set the timeout to the maximum value (which is the best we can do) and the SDHCI core will take care of the proper timeout handling.

Fixes: ba49cbd0936e ("mmc: sdhci-of-esdhc: add tuning support") Signed-off-by: Michael Walle michael@walle.cc Acked-by: Adrian Hunter adrian.hunter@intel.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20201022222337.19857-1-michael@walle.cc Signed-off-by: Ulf Hansson ulf.hansson@linaro.org

diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c index 0b45eff6fed4..baf7801a1804 100644 --- a/drivers/mmc/host/sdhci-of-esdhc.c +++ b/drivers/mmc/host/sdhci-of-esdhc.c @@ -1052,6 +1052,17 @@ static int esdhc_execute_tuning(struct mmc_host *mmc, u32 opcode)

esdhc_tuning_block_enable(host, true);

+ /* + * The eSDHC controller takes the data timeout value into account + * during tuning. If the SD card is too slow sending the response, the + * timer will expire and a "Buffer Read Ready" interrupt without data + * is triggered. This leads to tuning errors. + * + * Just set the timeout to the maximum value because the core will + * already take care of it in sdhci_send_tuning(). + */ + sdhci_writeb(host, 0xe, SDHCI_TIMEOUT_CONTROL); + hs400_tuning = host->flags & SDHCI_HS400_TUNING;

do {