linux-kernel - Re: [PATCH v2] mmc: Add quirk to disable DDR50 tuning

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Message-ID: <37fea39e-6687-4ad4-9dac-f09333953afa@intel.com>
Date: Wed, 2 Apr 2025 20:23:41 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Erick Shepherd <erick.shepherd@...com>, <linux-mmc@...r.kernel.org>
CC: <ulf.hansson@...aro.org>, <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 v2] mmc: Add quirk to disable DDR50 tuning

On 1/04/25 01:13, Erick Shepherd 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>

Acked-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
>  drivers/mmc/core/card.h   |  6 ++++++
>  drivers/mmc/core/quirks.h | 10 ++++++++++
>  drivers/mmc/core/sd.c     | 32 ++++++++++++++++++++++++--------
>  include/linux/mmc/card.h  |  1 +
>  4 files changed, 41 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/mmc/core/card.h b/drivers/mmc/core/card.h
> index 3205feb1e8ff..9cbdd240c3a7 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
> @@ -294,4 +295,9 @@ static inline int mmc_card_broken_sd_poweroff_notify(const struct mmc_card *c)
>  	return c->quirks & MMC_QUIRK_BROKEN_SD_POWEROFF_NOTIFY;
>  }
>  
> +static inline int mmc_card_no_uhs_ddr50_tuning(const struct mmc_card *c)
> +{
> +	return c->quirks & MMC_QUIRK_NO_UHS_DDR50_TUNING;
> +}
> +
>  #endif
> 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/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index cc757b850e79..fc3416027033 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -613,6 +613,29 @@ static int sd_set_current_limit(struct mmc_card *card, u8 *status)
>  	return 0;
>  }
>  
> +/*
> + * Determine if the card should tune or not.
> + */
> +static bool mmc_sd_use_tuning(struct mmc_card *card)
> +{
> +	/*
> +	 * SPI mode doesn't define CMD19 and tuning is only valid for SDR50 and
> +	 * SDR104 mode SD-cards. Note that tuning is mandatory for SDR104.
> +	 */
> +	if (mmc_host_is_spi(card->host))
> +		return false;
> +
> +	switch (card->host->ios.timing) {
> +	case MMC_TIMING_UHS_SDR50:
> +	case MMC_TIMING_UHS_SDR104:
> +		return true;
> +	case MMC_TIMING_UHS_DDR50:
> +		return !mmc_card_no_uhs_ddr50_tuning(card);
> +	}
> +
> +	return false;
> +}
> +
>  /*
>   * UHS-I specific initialization procedure
>   */
> @@ -656,14 +679,7 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
>  	if (err)
>  		goto out;
>  
> -	/*
> -	 * SPI mode doesn't define CMD19 and tuning is only valid for SDR50 and
> -	 * SDR104 mode SD-cards. Note that tuning is mandatory for SDR104.
> -	 */
> -	if (!mmc_host_is_spi(card->host) &&
> -		(card->host->ios.timing == MMC_TIMING_UHS_SDR50 ||
> -		 card->host->ios.timing == MMC_TIMING_UHS_DDR50 ||
> -		 card->host->ios.timing == MMC_TIMING_UHS_SDR104)) {
> +	if (mmc_sd_use_tuning(card)) {
>  		err = mmc_execute_tuning(card);
>  
>  		/*
> 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 */