From 5cc18e54d839047185ebcd16f1a32bbb733d3d77 Mon Sep 17 00:00:00 2001 From: Eugen Hristev Date: Thu, 30 Jun 2022 12:09:26 +0300 Subject: [PATCH] mmc: sdhci-of-at91: fix set_uhs_signaling rewriting of MC1R [ Upstream commit 1111848f44d4b46f23c36a68ca510efafbd2889d ] 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: e54596e47384 ("mmc: sdhci-of-at91: fix MMC_DDR_52 timing selection") Signed-off-by: Eugen Hristev Tested-by: Karl Olsen Acked-by: Adrian Hunter Link: https://lore.kernel.org/r/20220630090926.15061-1-eugen.hristev@microchip.com Signed-off-by: Ulf Hansson Signed-off-by: Sasha Levin --- 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 d1a1c548c515f..0452c312b65eb 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); } -- 2.39.5