Re: [PATCH] mmc: disable tuning when checking card presence

[Adrian Hunter <adrian.hunter@intel.com>]

On 18/06/21 1:42 pm, Ulf Hansson wrote:
> + Adrian
> 
> On Fri, 18 Jun 2021 at 10:23, Wolfram Sang
> <wsa+renesas@sang-engineering.com> wrote:
>>
>> When we use the alive callback, we expect a command to fail if the card
>> is not present. We should not trigger a retune then which will confuse
>> users with a failed retune on a removed card:
>>
>>  mmc2: tuning execution failed: -5
>>  mmc2: card 0001 removed
>>
>> Disable retuning in this code path.
>>
>> Reported-by: Ulrich Hecht <uli+renesas@fpond.eu>
>> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
>> ---
>>  drivers/mmc/core/core.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 54f0814f110c..eb792dd845a3 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -2088,6 +2088,9 @@ int _mmc_detect_card_removed(struct mmc_host *host)
>>         if (!host->card || mmc_card_removed(host->card))
>>                 return 1;
>>
>> +       /* we expect a failure if the card is removed */
>> +       mmc_retune_disable(host);
>> +
> 
> Some controllers require a retune after it has been runtime suspended.
> 
> In the above path, when called via the bus_ops->detect() callback, it
> could be that the controller may have been runtime suspended and then
> got resumed by the call to mmc_get_card().
> 
> I think we need something more clever here, to make sure we don't end
> up in that situation. I have looped in Adrian, to see if has some
> ideas for how this can be fixed.

Can we clarify, is the only problem that the error message is confusing?

> 
>>         ret = host->bus_ops->alive(host);
>>
>>         /*
>> @@ -2107,6 +2110,8 @@ int _mmc_detect_card_removed(struct mmc_host *host)
>>                 pr_debug("%s: card remove detected\n", mmc_hostname(host));
>>         }
>>
>> +       mmc_retune_enable(host);
>> +
>>         return ret;
>>  }
>>
>> --
>> 2.30.2
>>
> 
> Kind regards
> Uffe
>