From: Eugen Hristev eugen.hristev@microchip.com
[ 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@microchip.com Tested-by: Karl Olsen karl@micro-technic.com Acked-by: Adrian Hunter adrian.hunter@intel.com Link: https://lore.kernel.org/r/20220630090926.15061-1-eugen.hristev@microchip.com Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mmc/host/sdhci-of-at91.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
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); }