[U-Boot] [BUG] snow: mmc: SD card access broken: unable to select a mode

[Jean-Jacques Hiblot]

On 09/04/2018 16:03, Guillaume Gardet wrote:
>
>
> Le 09/04/2018 à 15:58, Jean-Jacques Hiblot a écrit :
>>
>>
>> On 09/04/2018 14:02, Guillaume Gardet wrote:
>>> Hi Jaehoon,
>>>
>>> There are problems with SD card access on Samsung Chromebook (snow) 
>>> with latest master (and also 2018.05-rc1 and 2018.03).
>>>
>>> eMMC is ok, but SD card access leads to 'unable to select a mode' 
>>> problem. If I disable HS mode, I can access the SD card without 
>>> problem:
>>> ******************************************************************************** 
>>>
>>> diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
>>> index 23f642980bf..28f4fa0f213 100644
>>> --- a/drivers/mmc/dw_mmc.c
>>> +++ b/drivers/mmc/dw_mmc.c
>>> @@ -508,7 +508,8 @@ void dwmci_setup_cfg(struct mmc_config *cfg, 
>>> struct dwmci_host *host,
>>>          cfg->host_caps |= MMC_MODE_4BIT;
>>>          cfg->host_caps &= ~MMC_MODE_8BIT;
>>>      }
>>> -    cfg->host_caps |= MMC_MODE_HS | MMC_MODE_HS_52MHz;
>>> +    /* Temp workaround for Chromebook snow to avoid the 'unable to 
>>> select a mode' error */
>>> +//     cfg->host_caps |= MMC_MODE_HS | MMC_MODE_HS_52MHz;
>>>
>>>      cfg->b_max = CONFIG_SYS_MMC_MAX_BLK_COUNT;
>>>  }
>>> ******************************************************************************** 
>>>
>>>
>>> Once we try to select HS mode, all access to SD card result in 
>>> failure, even when trying to setup a lower frequency mode, including 
>>> SD legacy at 25 MHz.
>>>
>>> Any idea what is going? Maybe you have fixes pending?
>>
>> Can try with MMC_MODE_HS | MMC_MODE_HS_52MHz but with a lower 
>> max-frequency (<25MHz) ? It would be interesting to know if it could 
>> come from a frequency limitation.
>
> I already tried to change SD_HS freq (in mmc_mode2freq) from 50000000 
> to 25000000 with no difference.
>
>> Is there some pad configuration to do when using higher frequency?
>
> I do not think so.
Can you enable the debug output and post a log ?
>
> Guillaume
>
>
>
>>
>> JJ
>>
>>>
>>>
>>> Guillaume
>>>
>>>
>>>
>>
>>
>
>