Re: [PATCH 1/3] mmc: sdhci: use WP GPIO in sdhci_check_ro()

Adrian Hunter
2019-01-16T13:01:07Z

On 15/01/19 6:28 PM, Thomas Petazzoni wrote:
> Even though SDHCI controllers may have a dedicated WP pin that can be
> queried using the SDHCI_PRESENT_STATE register, some platforms may
> chose to use a separate regular GPIO to route the WP signal. Such a
> GPIO is typically represented using the wp-gpios property in the
> Device Tree.
>
> Unfortunately, the current sdhci_check_ro() function does not make use
> of such GPIO when available: it either uses a host controller specific
> ->get_ro() operation, or uses the SDHCI_PRESENT_STATE. Several host
> controller specific ->get_ro() functions are implemented just to use
> check a WP GPIO state.
>
> Instead of pushing this to more controller-specific implementations,
> let's handle this in the core SDHCI code, just like it is already done
> for the CD GPIO in sdhci_get_cd().
>
> The below patch simply changes sdhci_check_ro() to use the value of
> the WP GPIO if available. We need to adjust the prototype of the
> function to use a mmc_host* as argument instead of sdhci_host*, since
> the mmc_can_gpio_ro() and mmc_gpio_get_ro() helpers take a mmc_host*.

Why not just use host->mmc

>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> ---
> drivers/mmc/host/sdhci.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index df05352b6a4a..63cc4bd033b9 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2022,8 +2022,9 @@ static int sdhci_get_cd(struct mmc_host *mmc)
> return !!(sdhci_readl(host, SDHCI_PRESENT_STATE) & SDHCI_CARD_PRESENT);
> }
>
> -static int sdhci_check_ro(struct sdhci_host *host)
> +static int sdhci_check_ro(struct mmc_host *mmc)
> {
> + struct sdhci_host *host = mmc_priv(mmc);
> unsigned long flags;
> int is_readonly;
>
> @@ -2031,6 +2032,8 @@ static int sdhci_check_ro(struct sdhci_host *host)
>
> if (host->flags & SDHCI_DEVICE_DEAD)
> is_readonly = 0;
> + else if (mmc_can_gpio_ro(mmc))
> + is_readonly = mmc_gpio_get_ro(mmc);

Perhaps host->ops->get_ro should be checked before mmc_can_gpio_ro()?

> else if (host->ops->get_ro)
> is_readonly = host->ops->get_ro(host);
> else
> @@ -2052,11 +2055,11 @@ static int sdhci_get_ro(struct mmc_host *mmc)
> int i, ro_count;
>
> if (!(host->quirks & SDHCI_QUIRK_UNSTABLE_RO_DETECT))
> - return sdhci_check_ro(host);
> + return sdhci_check_ro(mmc);
>
> ro_count = 0;
> for (i = 0; i < SAMPLE_COUNT; i++) {
> - if (sdhci_check_ro(host)) {
> + if (sdhci_check_ro(mmc)) {
> if (++ro_count > SAMPLE_COUNT / 2)
> return 1;
> }
>