Re: [PATCH v2 1/4] mmc: Add support for disabling write-protect detection

Ulf Hansson
2015-05-11T10:30:37Z

On 6 May 2015 at 20:31, Lars-Peter Clausen <lars@metafoo.de> wrote:
> It is not uncommon to see systems where there is no physical write-protect
> signal (e.g. when using eMMC or microSD card slots). For some controllers,
> which have a dedicated write-protection detection logic (like SDHCI
> controllers), the get_ro() callback can return bogus data in such a case.
>
> Instead of handling this on a per controller basis this patch adds a new
> capability flag to the MMC core that can be set to specify that the result
> of get_ro() is invalid. When the flag is set the core will not call
> get_ro() and assume that the card is always read-write.
>
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

Thanks, applied!

Kind regards
Uffe

> ---
> drivers/mmc/core/sd.c | 30 +++++++++++++++++++++++-------
> include/linux/mmc/host.h | 1 +
> 2 files changed, 24 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index 31a9ef2..8f6864a 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -804,6 +804,28 @@ int mmc_sd_get_csd(struct mmc_host *host, struct mmc_card *card)
> return 0;
> }
>
> +static int mmc_sd_get_ro(struct mmc_host *host)
> +{
> + int ro;
> +
> + /*
> + * Some systems don't feature a write-protect pin and don't need one.
> + * E.g. because they only have micro-SD card slot. For those systems
> + * assume that the SD card is always read-write.
> + */
> + if (host->caps2 & MMC_CAP2_NO_WRITE_PROTECT)
> + return 0;
> +
> + if (!host->ops->get_ro)
> + return -1;
> +
> + mmc_host_clk_hold(host);
> + ro = host->ops->get_ro(host);
> + mmc_host_clk_release(host);
> +
> + return ro;
> +}
> +
> int mmc_sd_setup_card(struct mmc_host *host, struct mmc_card *card,
> bool reinit)
> {
> @@ -855,13 +877,7 @@ int mmc_sd_setup_card(struct mmc_host *host, struct mmc_card *card,
> * Check if read-only switch is active.
> */
> if (!reinit) {
> - int ro = -1;
> -
> - if (host->ops->get_ro) {
> - mmc_host_clk_hold(card->host);
> - ro = host->ops->get_ro(host);
> - mmc_host_clk_release(card->host);
> - }
> + int ro = mmc_sd_get_ro(host);
>
> if (ro < 0) {
> pr_warn("%s: host does not support reading read-only switch, assuming write-enable\n",
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index b5bedae..3b92fd4 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -285,6 +285,7 @@ struct mmc_host {
> MMC_CAP2_HS400_1_2V)
> #define MMC_CAP2_HSX00_1_2V (MMC_CAP2_HS200_1_2V_SDR | MMC_CAP2_HS400_1_2V)
> #define MMC_CAP2_SDIO_IRQ_NOTHREAD (1 << 17)
> +#define MMC_CAP2_NO_WRITE_PROTECT (1 << 18) /* No physical write protect pin, assume that card is always read-write */
>
> mmc_pm_flag_t pm_caps; /* supported pm features */
>
> --
> 1.8.0
>