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References: <20220630090926.15061-1-eugen.hristev@microchip.com>
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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Tue, 12 Jul 2022 13:09:26 +0200
Message-ID: <CAPDyKFo9fOYzS0Mugk2bf05-PanHhcdwMqG_PXPdVSr7A-rXmA@mail.gmail.com>
Subject: Re: [PATCH] mmc: sdhci-of-at91: fix set_uhs_signaling rewriting of MC1R
To:     Eugen Hristev <eugen.hristev@microchip.com>
Cc:     adrian.hunter@intel.com, linux-mmc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Karl Olsen <karl@micro-technic.com>
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On Thu, 30 Jun 2022 at 11:09, Eugen Hristev <eugen.hristev@microchip.com> wrote:
>
> 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>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  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 10fb4cb2c731..cd0134580a90 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);
>  }
>
> --
> 2.25.1
>