Re: [PATCH] mmc: tmio: improve bringing HW to a sane state with MMC_POWER_OFF

[Ulf Hansson <ulf.hansson@linaro.org>]

On Wed, 25 Nov 2020 at 21:51, Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
>
> Further testing of error cases revealed that downgrade is not enough, so
> we need to reset the SCC which is done by calling the custom reset
> function. This reset function can distinguish between the various SDHI
> variants, so protecting the call with MIN_RCAR2 is enough here.
>
> Fixes: 24ce2d7b8bea ("mmc: tmio: bring tuning HW to a sane state with MMC_POWER_OFF")
> Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Applied for fixes, thanks!

Kind regards
Uffe


> ---
>
> I was also evaluating if tmio_mmc_reset() would be better than
> host->reset. I finally decided against it. This is the minimal change
> that we need and which fixes an actual issue. I can't see why we would
> want to terminate DMA because either everything went smooth and DMA
> completed or the DMA error has already been handled. I think. Please
> speak up if you disagree.
>
>  drivers/mmc/host/tmio_mmc_core.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
> index 7f4a28125010..a89547f5d733 100644
> --- a/drivers/mmc/host/tmio_mmc_core.c
> +++ b/drivers/mmc/host/tmio_mmc_core.c
> @@ -929,9 +929,9 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>         switch (ios->power_mode) {
>         case MMC_POWER_OFF:
>                 tmio_mmc_power_off(host);
> -               /* Downgrade ensures a sane state for tuning HW (e.g. SCC) */
> -               if (host->mmc->ops->hs400_downgrade)
> -                       host->mmc->ops->hs400_downgrade(host->mmc);
> +               /* For R-Car Gen2+, we need to reset SDHI specific SCC */
> +               if (host->pdata->flags & TMIO_MMC_MIN_RCAR2)
> +                       host->reset(host);
>                 host->set_clock(host, 0);
>                 break;
>         case MMC_POWER_UP:
> --
> 2.28.0
>