am654_sdhci: mmc fail to send stop cmd

[Faiz Abbas]

Jan,

On 21/07/20 10:52 pm, Jan Kiszka wrote:
> On 21.07.20 19:03, Faiz Abbas wrote:
>> Jan,
>>
>> On 21/07/20 12:06 pm, Jan Kiszka wrote:
>>> On 21.07.20 01:23, Jaehoon Chung wrote:
>>>> On 7/20/20 10:21 AM, Peng Fan wrote:
>>>>> Hi Jan,
>>>>>
>>>>>> Subject: am654_sdhci: mmc fail to send stop cmd
>>>>>>
>>>>>> Hi all,
>>>>>>
>>>>>> on one device with one specific SD-card (possibly an aging one), I'm seeing
>>>>>> frequent "mmc fail to send stop cmd" messages, followed by read errors
>>>>>> when loading kernel and dtb. -ETIMEDOUT is returned by mmd_send_cmd.
>>>>>> However, I can always resolve this by simply retrying the stop command like
>>>>>> this:
>>>>>>
>>>>>> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index
>>>>>> f36d11ddc8..9019d9f2ed 100644
>>>>>> --- a/drivers/mmc/mmc.c
>>>>>> +++ b/drivers/mmc/mmc.c
>>>>>> @@ -406,7 +406,11 @@ static int mmc_read_blocks(struct mmc *mmc, void
>>>>>> *dst, lbaint_t start,  #if !defined(CONFIG_SPL_BUILD) ||
>>>>>> defined(CONFIG_SPL_LIBCOMMON_SUPPORT)
>>>>>>                pr_err("mmc fail to send stop cmd\n");  #endif
>>>>>> -            return 0;
>>>>>> +            pr_err("retrying...\n");
>>>>>> +            if (mmc_send_cmd(mmc, &cmd, NULL)) {
>>>>>> +                pr_err("failed again\n");
>>>>>> +                return 0;
>>>>>> +            }
>>>>>>            }
>>>>>>        }
>>>>>>
>>>>>>
>>>>>> Hardware is our IOT2050, baseline is today's master (1c4b5038afcc) with
>>>>>> board-enabling and a bunch of patches from your tree [1]. However, already
>>>>>> 4d6da10ce611 exposes the problem.
>>>>>>
>>>>>> What could cause this?
>>>>>
>>>>> Where the timeout happen in driver?
>>>>>
>>>>> Did you try enlarge the timeout value?
>>>>
>>>> how about adding SDHCI_QUIRK_WAIT_SEND_CMD?
>>>
>>> I tried that already, but the result was even worse, a non-working mmc.
>>>
>>>> And as Peng's comment, It needs to find where return error in driver code.
>>>>
>>>
>>> As written in my other reply:
>>> https://gitlab.denx.de/u-boot/u-boot/-/blob/f12341a9529540113f01989149bbbeb68662a829/drivers/mmc/sdhci.c#L385
>>> Thus, it's reported by the hw.
>>>
>>
>> Its a command timeout for which we cannot program a higher timeout.
>>
>> Can you send a full failure log?
>>
> 
> [unrelated fsbl, spl stuff]
> 
> U-Boot 2020.07-00883-g4d6da10ce6-dirty (Jul 20 2020 - 06:30:08 +0200)
> 
> Model: Siemens IOT2050 Advanced Base Board
> DRAM:  2 GiB
> MMC:   sdhci at 4f80000: 1, sdhci at 04FA0000: 0
> Loading Environment from SPI Flash... SF: Detected w25q128 with page size 256 Bytes, erase size 64 KiB, total 16 MiB
> OK
> In:    serial
> Out:   serial
> Err:   serial
> Hit any key to stop autoboot:  0
> stat: 18000
> stat: 18000
> stat: 208000
> switch to partitions #0, OK
> mmc1(part 0) is current device
> ** No partition table - mmc 1 **
> switch to partitions #0, OK
> mmc0 is current device
> Scanning mmc 0:1...
> Found U-Boot script /boot/boot.scr
> 784 bytes read in 2 ms (382.8 KiB/s)
> ## Executing script at 83000000
> 65329 bytes read in 11 ms (5.7 MiB/s)
> stat: 18000
> mmc fail to send stop cmd, -110
> retrying...
> 17113096 bytes read in 1409 ms (11.6 MiB/s)
> Moving Image from 0x80080000 to 0x80200000, end=812c0000
> ## Flattened Device Tree blob at 82000000
>    Booting using the fdt blob at 0x82000000
>    Loading Device Tree to 00000000fdf0f000, end 00000000fdf21f30 ... OK
> 
> [kernel boot]
> 
> The diff I'm carrying on top of [1] is below.
> 
>> Also, does the same card + board combination work in kernel? That should help us point to hardware vs U-boot.
>>
> 
> The same card on the same board works without complaints with the kernel
> driver (5.8-rc5 at the moment). Even more strange, the same card a
> different board (IOT2050 Basic, some SoC series, slightly different
> type) does not throw those errors with the same U-Boot.

Was this card working with an older U-boot version and only failing in mainline?

> 
> Note that we are still carrying those clock swapping changes in [2].
> I've also tried to remove it, but it has no impact on this issue.
> 

One more thing to try is to reduce the speed mode to default as we are already gating frequency
to 25 MHz. Can you modify the sdhci-caps-mask to the following for sdhci1?

sdhci-caps-mask = <0x7 0x200000>;

Thanks,
Faiz