Re: [RFC][PATCH] Fix for Intel Baytrail-T errata regarding the non-functioning mmc_pwr pin

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On 3 June 2014 01:54, Jon Pry <jonpry@xxxxxxxxx> wrote:
> This bug effects Asus T100 as well as other Baytrail-T devices.
> Erratum in question can be found at
> http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/atom-Z36xxx-Z37xxx-spec-update.pdf
>
> Signed-off-by: Jon Pry <jonpry <at> gmail.com>
> ---
> diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
> index ebb3f39..ebed2a0 100644
> --- a/drivers/mmc/host/sdhci-acpi.c
> +++ b/drivers/mmc/host/sdhci-acpi.c
> @@ -123,7 +123,7 @@ static const struct sdhci_acpi_slot sdhci_acpi_slot_int_emmc = {
>
>  static const struct sdhci_acpi_slot sdhci_acpi_slot_int_sdio = {
>         .quirks  = SDHCI_QUIRK_BROKEN_CARD_DETECTION,
> -       .quirks2 = SDHCI_QUIRK2_HOST_OFF_CARD_ON,
> +       .quirks2 = SDHCI_QUIRK2_HOST_OFF_CARD_ON | SDHCI_QUIRK2_BROKEN_POWER_ENABLE,
>         .caps    = MMC_CAP_NONREMOVABLE | MMC_CAP_POWER_OFF_CARD,
>         .flags   = SDHCI_ACPI_RUNTIME_PM,
>         .pm_caps = MMC_PM_KEEP_POWER,
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 9a79fc4..5a0e928 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -22,6 +22,7 @@
>  #include <linux/scatterlist.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/gpio.h>
>
>  #include <linux/leds.h>
>
> @@ -1261,6 +1262,10 @@ static inline void sdhci_update_clock(struct sdhci_host *host)
>         sdhci_set_clock(host, clock);
>  }
>
> +static inline void sdhci_set_power_quirk(unsigned short power) {
> +       gpio_set_value(SDHCI_POWER_QUIRK_GPIO, power);
> +}
> +

I would suggest you to implement this through a gpio regulator instead.

In that way, you likely don't have to change that much in driver, right?

Kind regards
Uffe

>  static int sdhci_set_power(struct sdhci_host *host, unsigned short power)
>  {
>         u8 pwr = 0;
> @@ -1292,6 +1297,9 @@ static int sdhci_set_power(struct sdhci_host *host, unsigned short power)
>                 sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
>                 if (host->quirks2 & SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON)
>                         sdhci_runtime_pm_bus_off(host);
> +               /* The intel Bay Trail SoCs need to assert a GPIO as a work around */
> +               if (host->quirks2 & SDHCI_QUIRK2_BROKEN_POWER_ENABLE)
> +                       sdhci_set_power_quirk(0);
>                 return 0;
>         }
>
> @@ -1311,8 +1319,14 @@ static int sdhci_set_power(struct sdhci_host *host, unsigned short power)
>
>         pwr |= SDHCI_POWER_ON;
>
> +
>         sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
>
> +       /* The intel Bay Trail SoCs need to assert a GPIO as a work around */
> +       if (host->quirks2 & SDHCI_QUIRK2_BROKEN_POWER_ENABLE)
> +               sdhci_set_power_quirk(1);
> +
> +
>         if (host->quirks2 & SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON)
>                 sdhci_runtime_pm_bus_on(host);
>
> @@ -2820,6 +2841,18 @@ int sdhci_add_host(struct sdhci_host *host)
>                 host->flags &= ~SDHCI_USE_SDMA;
>         }
>
> +    if ((host->quirks2 & SDHCI_QUIRK2_BROKEN_POWER_ENABLE)) {
> +        printk("Using GPIO for power enable as it is marked broken\n");
> +        if (gpio_request(SDHCI_POWER_QUIRK_GPIO, "SDIO_PWR_EN") < 0) {
> +            printk("Unable to request GPIO. SDIO may be broken.");
> +                       host->quirks2 = host->quirks2 & ~SDHCI_QUIRK2_BROKEN_POWER_ENABLE;
> +        }
> +        else if (gpio_direction_output(SDHCI_POWER_QUIRK_GPIO, 0) < 0) {
> +            printk("Unable to set GPIO direction. SDIO may be broken.");
> +                       host->quirks2 = host->quirks2 & ~SDHCI_QUIRK2_BROKEN_POWER_ENABLE;
> +        }
> +    }
> +
>         if ((host->version >= SDHCI_SPEC_200) &&
>                 (caps[0] & SDHCI_CAN_DO_ADMA2))
>                 host->flags |= SDHCI_USE_ADMA;
> @@ -3325,6 +3358,10 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
>         tasklet_kill(&host->card_tasklet);
>         tasklet_kill(&host->finish_tasklet);
>
> +    if (host->quirks2 & SDHCI_QUIRK2_BROKEN_POWER_ENABLE) {
> +        gpio_free(SDHCI_POWER_QUIRK_GPIO);
> +    }
> +
>         if (host->vmmc) {
>                 regulator_disable(host->vmmc);
>                 regulator_put(host->vmmc);
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 0a3ed01..027fcd1 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -84,11 +84,12 @@
>  #define   SDHCI_CTRL_ADMA64    0x18
>  #define   SDHCI_CTRL_8BITBUS   0x20
>
>  #define SDHCI_POWER_CONTROL    0x29
>  #define  SDHCI_POWER_ON                0x01
>  #define  SDHCI_POWER_180       0x0A
>  #define  SDHCI_POWER_300       0x0C
>  #define  SDHCI_POWER_330       0x0E
> +#define SDHCI_POWER_QUIRK_GPIO 195 /*GPIO offset 41 of SCORE device is SD3_PWR_EN*/
>
>  #define SDHCI_BLOCK_GAP_CONTROL        0x2A
>
> diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
> index 7be12b8..92cec16 100644
> --- a/include/linux/mmc/sdhci.h
> +++ b/include/linux/mmc/sdhci.h
> @@ -102,6 +102,9 @@ struct sdhci_host {
>  #define SDHCI_QUIRK2_BROKEN_HS200                      (1<<6)
>  /* Controller does not support DDR50 */
>  #define SDHCI_QUIRK2_BROKEN_DDR50                      (1<<7)
> +/* Controller cannot initialize power (must use GPIO instead) */
> +#define SDHCI_QUIRK2_BROKEN_POWER_ENABLE               (1<<8)
> +
>
>         int irq;                /* Device IRQ */
>         void __iomem *ioaddr;   /* Mapped address */
> --
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