On 21 April 2017 at 12:08, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> The SDIO card state might be being preserved during hibernation, for
> example a SDIO wifi card supporting WOWLAN. That state will be lost if an
> SDIO reset is done. One way to avoid that would be to build mmc core as a
> module and simply not load it until after attempting to restore the
> hibernation image. However that won't work if the hibernation image is
> stored on eMMC which, of course, requires mmc core.
I don't follow here. Are you saying the SDIO card is kept powered in
hibernation, as to be able to support WOWLAN, right?
Then, it feels plain wrong the mmc_rescan() tries to re-initialize it.
That should never happen, unless something is broken of course.
Kind regards
Uffe
>
> It is assumed on such systems that the platform will power cycle the SDIO
> card or not as necessary so that the SDIO reset is not needed. Add a
> capability flag to reflect that and use it to skip the SDIO reset at scan
> time.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
> drivers/mmc/core/core.c | 6 +++++-
> include/linux/mmc/host.h | 1 +
> 2 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 6987976252ad..178e23bf0c30 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2639,8 +2639,12 @@ static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
> * if the card is being re-initialized, just send it. CMD52
> * should be ignored by SD/eMMC cards.
> * Skip it if we already know that we do not support SDIO commands
> + * Also skip it if we know this host controller has a SDIO card that
> + * needs to be able to restore from hibernation without losing the card
> + * state e.g. an SDIO wifi card supporting WOWLAN.
> */
> - if (!(host->caps2 & MMC_CAP2_NO_SDIO))
> + if (!(host->caps2 & MMC_CAP2_NO_SDIO) &&
> + !(host->caps2 & MMC_CAP2_NO_SDIO_RESET))
> sdio_reset(host);
>
> mmc_go_idle(host);
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 78c544e296cd..187a7ba41364 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -281,6 +281,7 @@ struct mmc_host {
> u32 caps2; /* More host capabilities */
>
> #define MMC_CAP2_BOOTPART_NOACC (1 << 0) /* Boot partition no access */
> +#define MMC_CAP2_NO_SDIO_RESET (1 << 1) /* Do not SDIO reset at scan */
> #define MMC_CAP2_FULL_PWR_CYCLE (1 << 2) /* Can do full power cycle */
> #define MMC_CAP2_HS200_1_8V_SDR (1 << 5) /* can support */
> #define MMC_CAP2_HS200_1_2V_SDR (1 << 6) /* can support */
> --
> 1.9.1
>
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