This is a note to let you know that I've just added the patch titled mmc: sdhci-of-at91: fix set_uhs_signaling rewriting of MC1R to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mmc-sdhci-of-at91-fix-set_uhs_signaling-rewriting-of.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 87d34c5f4927d873a7c779a48c9b91664adc8162 Author: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> Date: Thu Jun 30 12:09:26 2022 +0300 mmc: sdhci-of-at91: fix set_uhs_signaling rewriting of MC1R [ Upstream commit 5987e6ded29d52e42fc7b06aa575c60a25eee38e ] In set_uhs_signaling, the DDR bit is being set by fully writing the MC1R register. This can lead to accidental erase of certain bits in this register. Avoid this by doing a read-modify-write operation. Fixes: d0918764c17b ("mmc: sdhci-of-at91: fix MMC_DDR_52 timing selection") Signed-off-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> Tested-by: Karl Olsen <karl@xxxxxxxxxxxxxxxxx> Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx> Link: https://lore.kernel.org/r/20220630090926.15061-1-eugen.hristev@xxxxxxxxxxxxx Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c index d1a1c548c515..0452c312b65e 100644 --- a/drivers/mmc/host/sdhci-of-at91.c +++ b/drivers/mmc/host/sdhci-of-at91.c @@ -100,8 +100,13 @@ static void sdhci_at91_set_clock(struct sdhci_host *host, unsigned int clock) static void sdhci_at91_set_uhs_signaling(struct sdhci_host *host, unsigned int timing) { - if (timing == MMC_TIMING_MMC_DDR52) - sdhci_writeb(host, SDMMC_MC1R_DDR, SDMMC_MC1R); + u8 mc1r; + + if (timing == MMC_TIMING_MMC_DDR52) { + mc1r = sdhci_readb(host, SDMMC_MC1R); + mc1r |= SDMMC_MC1R_DDR; + sdhci_writeb(host, mc1r, SDMMC_MC1R); + } sdhci_set_uhs_signaling(host, timing); }