Re: [PATCH] mmc: core: Wait for command setting 'Power Off Notification' bit to complete

[Ulf Hansson]

On Sat, 15 Jan 2022 at 13:15, Andrey Skvortsov
<andrej.skvortzov@xxxxxxxxx> wrote:
>
> SD card is allowed to signal busy on DAT0 up to 1s after the
> CMD49. According to SD spec (version 6.0 section 5.8.1.3) first host
> waits until busy of CMD49 is released and only then polls Power
> Management Status register up to 1s until the card indicates ready to
> power off.
>
> Without waiting for busy before polling status register sometimes card
> becomes unresponsive and system fails to suspend:
>
>   [  205.907459] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
>   [  206.421274] sunxi-mmc 1c0f000.mmc: data error, sending stop command
>   [  206.421321] sunxi-mmc 1c0f000.mmc: send stop command failed
>   [  206.421347] mmc0: error -110 reading status reg of PM func
>   [  206.421366] PM: dpm_run_callback(): mmc_bus_suspend+0x0/0x74 returns -110
>   [  206.421402] mmcblk mmc0:aaaa: PM: failed to suspend async: error -110
>   [  206.437064] PM: Some devices failed to suspend, or early wake event detected

Thanks for your patch!

I recall I was hesitating on adding another busy completion check for
this, but thought polling the status register for the power management
function should be sufficient.

>
> Tested with Sandisk Extreme PRO A2 64GB on Allwinner A64 system.

I will give this patch a try too, to make sure it still works on my
side. Assuming that works fine, I will queue this up for fixes and by
adding a fixes/stable tag.

>
> Signed-off-by: Andrey Skvortsov <andrej.skvortzov@xxxxxxxxx>

Kind regards
Uffe

> ---
>  drivers/mmc/core/sd.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index e223275bbad1..842b886bdd4e 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -66,7 +66,7 @@ static const unsigned int sd_au_size[] = {
>                 __res & __mask;                                         \
>         })
>
> -#define SD_POWEROFF_NOTIFY_TIMEOUT_MS 2000
> +#define SD_POWEROFF_NOTIFY_TIMEOUT_MS 1000
>  #define SD_WRITE_EXTR_SINGLE_TIMEOUT_MS 1000
>
>  struct sd_busy_data {
> @@ -1663,6 +1663,13 @@ static int sd_poweroff_notify(struct mmc_card *card)
>                 goto out;
>         }
>
> +       /* Find out when the command is completed. */
> +       err = mmc_poll_for_busy(card, SD_POWEROFF_NOTIFY_TIMEOUT_MS, false,
> +                               MMC_BUSY_EXTR_SINGLE);
> +
> +       if (err)
> +               goto out;
> +
>         cb_data.card = card;
>         cb_data.reg_buf = reg_buf;
>         err = __mmc_poll_for_busy(card->host, SD_POWEROFF_NOTIFY_TIMEOUT_MS,
> --
> 2.34.1
>