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

[Guillaume Gardet]

Le 09/04/2018 à 18:02, Guillaume Gardet a écrit :
>
>
> Le 09/04/2018 à 17:18, Jean-Jacques Hiblot a écrit :
>>
>>
>> On 09/04/2018 16:46, Guillaume Gardet wrote:
>>>
>>>
>>> Le 09/04/2018 à 16:21, Jean-Jacques Hiblot a écrit :
>>>>
>>>>
>>>> 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 ?
>>>
>>> Here is the log from u-boot built from u-boot-mmc (latest commit: 21c2ac32b845)
>>> Yes, I have no serial, so I retyped the messages, so I hope there is no typo:
>>> **********************************************************************
>>> selecting mode MMC legacy (freq : 0 MHz)
>>> selecting mode MMC legacy (freq : 25 MHz)
>>> sd card: widths [4, 1] modes [SD Legacy, SD High SPeed (50MHz)]
>>> host: widths [4, 1] modes [MMC legacy, SD Legacy, MMC High Speed (26MHz), SD High Speed (50MHz), MMC High Speed (52MHz), MMC DDR52 (52MHz)]
>>> trying mode SD High Speed (50MHz) width 4 (at 50 MHz)
>>> selecting mode SD High Speed (50 MHz) (freq : 50 MHz)
>>> unable to read ssr
>>> selecting mode SD Legacy (25 MHz) (freq : 25 MHz)
>>> trying mode SD High Speed (50MHz) width 1 (at 50 MHz)
>> So it fails either in sd_select_bus_width() or sd_set_card_speed()
>> Can you try to limit the bus width to 1 ? Does it fail also at 50 MHz ?
>
> Yes, it fails too.

If I disable sd_set_card_speed, then it is working fine.

Guillaume

>
> Guillaume
>
>>
>>> selecting mode SD Legacy (25 MHz) (freq : 25 MHz)
>>> trying mode SD Legacy (25MHz) width 4 (at 25 MHz)
>>> selecting mode SD Legacy (25 MHz) (freq : 25 MHz)
>>> trying mode SD Legacy (25MHz) width 1 (at 25 MHz)
>>> selecting mode SD Legacy (25 MHz) (freq : 25 MHz)
>>> unable to select a mode
>>> mmc_init: -524, time 127
>>> ** Bad device mmc 1 **
>>> **********************************************************************
>>>
>>> Note that eMMC (on mmc 0) is working fine with MMC DDR52 (52MHz).
>>>
>>> Guillaume
>>>
>>
>>
>