Re: [PATCH 3/3] mmc: do not attempt UHS 1.8v support if board does not support it

[Alan Cooper <alcooperx@gmail.com>]

I recently added a patch that prevents the switch to 1.8v if the host
capabilities register does not indicate support for any of the UHS
speeds (SDR50, DDR50, SDR104). This allowed our controller to work
with UHS cards in HS mode (50MHz, 3.3v).

Al

On Sun, May 27, 2012 at 9:36 PM,  <philipspatches@gmail.com> wrote:
> From: Philip Rakity <prakity@marvell.com>
>
> We have h/w that does not support 1.8v signaling even though the
> controller does support this.  If we enable 1.8v support UHS
> cards are recognised but recovery to 3.3v is not possible
> depending on the SD card.
>
> Ensure that when we do not support 1.8v UHS mode cards can
> work (in non UHS mode).
>
> Signed-off-by: Philip Rakity <prakity@marvell.com>
> ---
>  drivers/mmc/host/sdhci.c  |   71 +++++++++++++++++++++++---------------------
>  include/linux/mmc/sdhci.h |    3 ++
>  2 files changed, 40 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 8d8dff0..f9b37c4 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2782,27 +2782,45 @@ int sdhci_add_host(struct sdhci_host *host)
>            mmc_card_is_removable(mmc))
>                mmc->caps |= MMC_CAP_NEEDS_POLL;
>
> -       /* Any UHS-I mode in caps implies SDR12 and SDR25 support. */
> -       if (caps[1] & (SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
> -                      SDHCI_SUPPORT_DDR50))
> -               mmc->caps |= MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25;
> +       if (!(host->quirks2 & SDHCI_QUIRK2_HOST_NO_UHS_1_8V_SUPPORT)) {
> +               /* Any UHS-I mode in caps implies SDR12 and SDR25 support. */
> +               if (caps[1] & (SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
> +                              SDHCI_SUPPORT_DDR50))
> +                       mmc->caps |= MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25;
> +
> +               /* SDR104 supports also implies SDR50 support */
> +               if (caps[1] & SDHCI_SUPPORT_SDR104)
> +                       mmc->caps |= MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_SDR50;
> +               else if (caps[1] & SDHCI_SUPPORT_SDR50)
> +                       mmc->caps |= MMC_CAP_UHS_SDR50;
> +
> +               if (caps[1] & SDHCI_SUPPORT_DDR50)
> +                       mmc->caps |= MMC_CAP_UHS_DDR50;
> +
> +               /* Does the host need tuning for SDR50? */
> +               if (caps[1] & SDHCI_USE_SDR50_TUNING)
> +                       host->flags |= SDHCI_SDR50_NEEDS_TUNING;
> +
> +               /* Does the host need tuning for HS200? */
> +               if (mmc->caps2 & MMC_CAP2_HS200)
> +                       host->flags |= SDHCI_HS200_NEEDS_TUNING;
> +
> +               /* Initial value for re-tuning timer count */
> +               host->tuning_count =
> +                       (caps[1] & SDHCI_RETUNING_TIMER_COUNT_MASK) >>
> +                               SDHCI_RETUNING_TIMER_COUNT_SHIFT;
>
> -       /* SDR104 supports also implies SDR50 support */
> -       if (caps[1] & SDHCI_SUPPORT_SDR104)
> -               mmc->caps |= MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_SDR50;
> -       else if (caps[1] & SDHCI_SUPPORT_SDR50)
> -               mmc->caps |= MMC_CAP_UHS_SDR50;
> -
> -       if (caps[1] & SDHCI_SUPPORT_DDR50)
> -               mmc->caps |= MMC_CAP_UHS_DDR50;
> -
> -       /* Does the host need tuning for SDR50? */
> -       if (caps[1] & SDHCI_USE_SDR50_TUNING)
> -               host->flags |= SDHCI_SDR50_NEEDS_TUNING;
> +               /*
> +                * In case Re-tuning Timer is not disabled, the actual value of
> +                * re-tuning timer will be 2 ^ (n - 1).
> +                */
> +               if (host->tuning_count)
> +                       host->tuning_count = 1 << (host->tuning_count - 1);
>
> -       /* Does the host need tuning for HS200? */
> -       if (mmc->caps2 & MMC_CAP2_HS200)
> -               host->flags |= SDHCI_HS200_NEEDS_TUNING;
> +               /* Re-tuning mode supported by the Host Controller */
> +               host->tuning_mode = (caps[1] & SDHCI_RETUNING_MODE_MASK) >>
> +                                    SDHCI_RETUNING_MODE_SHIFT;
> +       }
>
>        /* Driver Type(s) (A, C, D) supported by the host */
>        if (caps[1] & SDHCI_DRIVER_TYPE_A)
> @@ -2821,21 +2839,6 @@ int sdhci_add_host(struct sdhci_host *host)
>        else
>                mmc->power_notify_type = MMC_HOST_PW_NOTIFY_NONE;
>
> -       /* Initial value for re-tuning timer count */
> -       host->tuning_count = (caps[1] & SDHCI_RETUNING_TIMER_COUNT_MASK) >>
> -                             SDHCI_RETUNING_TIMER_COUNT_SHIFT;
> -
> -       /*
> -        * In case Re-tuning Timer is not disabled, the actual value of
> -        * re-tuning timer will be 2 ^ (n - 1).
> -        */
> -       if (host->tuning_count)
> -               host->tuning_count = 1 << (host->tuning_count - 1);
> -
> -       /* Re-tuning mode supported by the Host Controller */
> -       host->tuning_mode = (caps[1] & SDHCI_RETUNING_MODE_MASK) >>
> -                            SDHCI_RETUNING_MODE_SHIFT;
> -
>        ocr_avail = 0;
>
>        host->vmmc = regulator_get(mmc_dev(mmc), "vmmc");
> diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
> index e9051e1..2367939 100644
> --- a/include/linux/mmc/sdhci.h
> +++ b/include/linux/mmc/sdhci.h
> @@ -92,6 +92,9 @@ struct sdhci_host {
>
>  #define SDHCI_QUIRK2_HOST_OFF_CARD_ON                  (1<<0)
>
> +/* host or board design does support 1.8v signaling */
> +#define SDHCI_QUIRK2_HOST_NO_UHS_1_8V_SUPPORT          (1<<1)
> +
>        int irq;                /* Device IRQ */
>        void __iomem *ioaddr;   /* Mapped address */
>
> --
> 1.7.0.4
>
> --
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