linux-kernel - Re: [PATCH] mmc: Add quirk to disable DDR50 tuning

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Message-ID: <CAPDyKFqrT0zXVRya=sgEOdjmn7D6xb-e+nD9Q4JpVnh1ddu_Fw@mail.gmail.com>
Date: Mon, 17 Mar 2025 11:40:12 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Erick Shepherd <erick.shepherd@...com>
Cc: linux-mmc@...r.kernel.org, adrian.hunter@...el.com, keita.aihara@...y.com, 
	linux-kernel@...r.kernel.org, avri.altman@....com, 
	wsa+renesas@...g-engineering.com, jason.lai@...esyslogic.com.tw, 
	jeff.johnson@....qualcomm.com, victor.shih@...esyslogic.com.tw, 
	andy-ld.lu@...iatek.com, dsimic@...jaro.org, jonathan@...pberrypi.com
Subject: Re: [PATCH] mmc: Add quirk to disable DDR50 tuning

On Fri, 14 Mar 2025 at 20:58, Erick Shepherd <erick.shepherd@...com> wrote:
>
> Adds the MMC_QUIRK_NO_UHS_DDR50_TUNING quirk and updates
> mmc_execute_tuning() to return 0 if that quirk is set. This fixes an
> issue on certain Swissbit SD cards that do not support DDR50 tuning
> where tuning requests caused I/O errors to be thrown.
>
> Signed-off-by: Erick Shepherd <erick.shepherd@...com>
> ---
>  drivers/mmc/core/card.h   |  1 +
>  drivers/mmc/core/core.c   |  4 ++++
>  drivers/mmc/core/quirks.h | 10 ++++++++++
>  include/linux/mmc/card.h  |  1 +
>  4 files changed, 16 insertions(+)
>
> diff --git a/drivers/mmc/core/card.h b/drivers/mmc/core/card.h
> index 3205feb1e8ff..756f80024635 100644
> --- a/drivers/mmc/core/card.h
> +++ b/drivers/mmc/core/card.h
> @@ -89,6 +89,7 @@ struct mmc_fixup {
>  #define CID_MANFID_MICRON       0x13
>  #define CID_MANFID_SAMSUNG      0x15
>  #define CID_MANFID_APACER       0x27
> +#define CID_MANFID_SWISSBIT     0x5D
>  #define CID_MANFID_KINGSTON     0x70
>  #define CID_MANFID_HYNIX       0x90
>  #define CID_MANFID_KINGSTON_SD 0x9F
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 5241528f8b90..8962992f05aa 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -937,6 +937,10 @@ int mmc_execute_tuning(struct mmc_card *card)
>         if (!host->ops->execute_tuning)
>                 return 0;
>
> +       if ((card->quirks & MMC_QUIRK_NO_UHS_DDR50_TUNING) &&
> +           host->ios.timing == MMC_TIMING_UHS_DDR50)
> +               return 0;
> +

Please move this to mmc_sd_init_uhs_card() instead. Moreover, please
add a helper in drivers/mmc/core/card.h for
MMC_QUIRK_NO_UHS_DDR50_TUNING, similar to other quirks.

>         if (host->cqe_on)
>                 host->cqe_ops->cqe_off(host);
>
> diff --git a/drivers/mmc/core/quirks.h b/drivers/mmc/core/quirks.h
> index 89b512905be1..7f893bafaa60 100644
> --- a/drivers/mmc/core/quirks.h
> +++ b/drivers/mmc/core/quirks.h
> @@ -34,6 +34,16 @@ static const struct mmc_fixup __maybe_unused mmc_sd_fixups[] = {
>                    MMC_QUIRK_BROKEN_SD_CACHE | MMC_QUIRK_BROKEN_SD_POWEROFF_NOTIFY,
>                    EXT_CSD_REV_ANY),
>
> +       /*
> +        * Swissbit series S46-u cards throw I/O errors during tuning requests
> +        * after the initial tuning request expectedly times out. This has
> +        * only been observed on cards manufactured on 01/2019 that are using
> +        * Bay Trail host controllers.
> +        */
> +       _FIXUP_EXT("0016G", CID_MANFID_SWISSBIT, 0x5342, 2019, 1,
> +                  0, -1ull, SDIO_ANY_ID, SDIO_ANY_ID, add_quirk_sd,
> +                  MMC_QUIRK_NO_UHS_DDR50_TUNING, EXT_CSD_REV_ANY),
> +
>         END_FIXUP
>  };
>
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 526fce581657..ddcdf23d731c 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -329,6 +329,7 @@ struct mmc_card {
>  #define MMC_QUIRK_BROKEN_SD_CACHE      (1<<15) /* Disable broken SD cache support */
>  #define MMC_QUIRK_BROKEN_CACHE_FLUSH   (1<<16) /* Don't flush cache until the write has occurred */
>  #define MMC_QUIRK_BROKEN_SD_POWEROFF_NOTIFY    (1<<17) /* Disable broken SD poweroff notify support */
> +#define MMC_QUIRK_NO_UHS_DDR50_TUNING  (1<<18) /* Disable DDR50 tuning */
>
>         bool                    written_flag;   /* Indicates eMMC has been written since power on */
>         bool                    reenable_cmdq;  /* Re-enable Command Queue */
> --
> 2.43.0
>

Other than the minor things above, this seems reasonable to me!

Kind regards
Uffe