linux-kernel - Re: [PATCH] mmc: dw_mmc: Dont wait for DRTO on Write RSP error

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Date:   Thu, 23 Sep 2021 13:44:36 +0900
From:   Jaehoon Chung <jh80.chung@...sung.com>
To:     Christian Löhle <CLoehle@...erstone.com>,
        "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: dw_mmc: Dont wait for DRTO on Write RSP error

On 9/23/21 7:52 AM, Jaehoon Chung wrote:
> Hi Chritstian,
> 
> On 9/16/21 2:59 PM, Christian Löhle wrote:
>> Only wait for DRTO on reads, otherwise the driver hangs.
>>
>> The driver prevents sending CMD12 on response errors like CRCs.
>> According to the comment this is because some cards have problems
>> with this during the UHS tuning sequence.
>> Unfortunately this workaround currently also applies for any command
>> with data.
>> On reads this will set the drto timer which then triggers after a while.
>> On writes this will not set any timer and the tasklet will not be
>> scheduled again.
>> I cannot attest for the UHS workarounds need, but even if so, it should
>> at most apply to reads.
>> I have observed many hangs when CMD25 response contained a CRC error.
>> This patch fixes this without touching the actual UHS tuning workaround.
> 
> Sorry for reply too late. I'm checking your patch on my target. 
> I will share the result.
> 
> Best Regards,
> Jaehoon Chung
> 
>>
>> Signed-off-by: Christian Loehle <cloehle@...erstone.com>

Reviewed-by: Jaehoon Chung <jh80.chung@...sung.com>

Best Regards,
Jaehoon Chung

>> ---
>>  drivers/mmc/host/dw_mmc.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 6578cc64ae9e..22cf13dc799b 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -2081,7 +2081,8 @@ static void dw_mci_tasklet_func(struct tasklet_struct *t)
>>  				 * delayed. Allowing the transfer to take place
>>  				 * avoids races and keeps things simple.
>>  				 */
>> -				if (err != -ETIMEDOUT) {
>> +				if (err != -ETIMEDOUT &&
>> +				    host->dir_status == DW_MCI_RECV_STATUS) {
>>  					state = STATE_SENDING_DATA;
>>  					continue;
>>  				}
>>
> 
>