On 10 April 2018 at 09:00, Harish Jenny K N <harish_kandiga@xxxxxxxxxx> wrote:
> This patch adds a quirk to limit clock rate which
> can be used to reduce the SDIO clock rate for some
> chips with broken UHS.
>
> Signed-off-by: Harish Jenny K N <harish_kandiga@xxxxxxxxxx>
> ---
> drivers/mmc/core/card.h | 6 ++++++
> drivers/mmc/core/sdio.c | 6 +++++-
> include/linux/mmc/card.h | 1 +
> 3 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/card.h b/drivers/mmc/core/card.h
> index 9c821ee..1170feb 100644
> --- a/drivers/mmc/core/card.h
> +++ b/drivers/mmc/core/card.h
> @@ -149,6 +149,12 @@ static inline void __maybe_unused remove_quirk(struct mmc_card *card, int data)
> card->quirks &= ~data;
> }
>
> +static inline void __maybe_unused add_limit_rate_quirk(struct mmc_card *card,
> + int data)
> +{
> + card->quirk_max_rate = data;
> +}
> +
> /*
> * Quirk add/remove for MMC products.
> */
> diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
> index c599a62..24b510b 100644
> --- a/drivers/mmc/core/sdio.c
> +++ b/drivers/mmc/core/sdio.c
> @@ -444,6 +444,7 @@ static int sdio_set_bus_speed_mode(struct mmc_card *card)
> unsigned int bus_speed, timing;
> int err;
> unsigned char speed;
> + unsigned int max_rate;
>
> /*
> * If the host doesn't support any of the UHS-I modes, fallback on
> @@ -500,9 +501,12 @@ static int sdio_set_bus_speed_mode(struct mmc_card *card)
> if (err)
> return err;
>
> + max_rate = min_not_zero(card->quirk_max_rate,
> + card->sw_caps.uhs_max_dtr);
> +
> if (bus_speed) {
> mmc_set_timing(card->host, timing);
> - mmc_set_clock(card->host, card->sw_caps.uhs_max_dtr);
> + mmc_set_clock(card->host, max_rate);
> }
This takes care of limiting the clock rate for SDIO UHS cards. As this
currently is the only case you want to cover I am fine with keeping
this as is.
Anyway, my point is, I think this quirk may also be useful for some
high-speed SDIO cards, all SD cards and (e)MMC cards. Although let's
skip that for now.
>
> return 0;
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 279b390..5ebc478 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -252,6 +252,7 @@ struct mmc_card {
> #define MMC_TYPE_SD_COMBO 3 /* SD combo (IO+mem) card */
> unsigned int state; /* (our) card state */
> unsigned int quirks; /* card quirks */
> + unsigned int quirk_max_rate; /* max rate set by quirks */
> #define MMC_QUIRK_LENIENT_FN0 (1<<0) /* allow SDIO FN0 writes outside of the VS CCCR range */
> #define MMC_QUIRK_BLKSZ_FOR_BYTE_MODE (1<<1) /* use func->cur_blksize */
> /* for byte mode */
> --
> 1.9.1
>
>
Thanks, queued for 4.18!
Kind regards
Uffe
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
