Re: [PATCH 2/3] mmc: add MMC_QUIRK_BROKEN_CLK_GATING

Philip Rakity
2011-01-10T15:58:57Z

On Jan 9, 2011, at 8:26 AM, Pierre Tardy wrote:

> Some sdio card are not following sdio standard, and does not work
> when the sdio bus's clock is gated
>
> To keep functionnality for all legacy driver, we turn this quirk on
> for every sdio card.
> Drivers needs to disable the quirk manually when someone verified that their
> supported card works with clock gating.
>
> Signed-off-by: Pierre Tardy <tardyp@gmail.com>
> ---
> drivers/mmc/core/host.c | 5 +----
> drivers/mmc/core/quirks.c | 11 +++++++++++
> include/linux/mmc/card.h | 1 +
> 3 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index b3ac6c5..461e6a1 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -160,10 +160,7 @@ static bool mmc_host_may_gate_card(struct mmc_card *card)
> * gate the clock, because there is somebody out there that may still
> * be using it.
> */
> - if (mmc_card_sdio(card))
> - return false;
> -
> - return true;
> + return !(card->quirks & MMC_QUIRK_BROKEN_CLK_GATING);
> }

Since the code is not called that often could you change the above code to:

> if (mmc_card_sdio(card))
> return !(card->quirks & MMC_QUIRK_BROKEN_CLK_GATING);
return true;

more obvious that quirk only applies to sdio.

>
> /**
> diff --git a/drivers/mmc/core/quirks.c b/drivers/mmc/core/quirks.c
> index d8a5fec..fe467c8 100644
> --- a/drivers/mmc/core/quirks.c
> +++ b/drivers/mmc/core/quirks.c
> @@ -32,7 +32,18 @@ static void add_quirk(struct mmc_card *card, int data)
> card->quirks |= data;
> }
>
> +/*
> + * This hook just adds a quirk for all sdio devices
> + */
> +static void add_quirk_for_sdio_devices(struct mmc_card *card, int data)
> +{
> + if (mmc_card_sdio(card))
> + card->quirks |= data;
> +}
> +
> static const struct mmc_fixup mmc_fixup_methods[] = {
> + { SDIO_ANY_ID, SDIO_ANY_ID,
> + add_quirk_for_sdio_devices, MMC_QUIRK_BROKEN_CLK_GATING }
> { 0 }
> };
>
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index a498d53..3fe9db0 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -121,6 +121,7 @@ struct mmc_card {
> /* for byte mode */
> #define MMC_QUIRK_NONSTD_SDIO (1<<2) /* non-standard SDIO card attached */
> /* (missing CIA registers) */
> +#define MMC_QUIRK_BROKEN_CLK_GATING (1<<3) /* clock gating the sdio bus will make card fail */
>
> unsigned int erase_size; /* erase size in sectors */
> unsigned int erase_shift; /* if erase unit is power 2 */
> --
> 1.7.1
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html