Re: [RFC PATCH] mmc: dw_mmc: add status check before clock update

Jaehoon Chung
2015-02-13T07:30:48Z

Hi, Andrzej.

On 02/13/2015 01:53 AM, Javier Martinez Canillas wrote:
> Hello Andrzej,
>
> On Wed, Feb 11, 2015 at 10:06 AM, Andrzej Hajda <a.hajda@samsung.com> wrote:
>> On 02/11/2015 09:32 AM, Jaehoon Chung wrote:
>>> On 02/11/2015 04:51 PM, Andrzej Hajda wrote:
>>>> Hi,
>>>>
>>>> Thanks for comments.
>>>>
>>>> On 02/10/2015 03:54 PM, Alim Akhtar wrote:
>>>>> Hi Andrzej,
>>>>>
>>>>> On Tue, Feb 10, 2015 at 7:59 PM, Andrzej Hajda <a.hajda@samsung.com> wrote:
>>>>>> According to specs for version 250A, status register should be
>>>>>> tested before clock update. Otherwise in case MMC card is missing
>>>>>> mci_send_cmd timeouts and subsequent CTYPE registry write causes system hang.
>>>>>> This behavior has been observed on Exynos5422/Odroid-XU3.
>
> I've also observed the same behavior (mmc command send timing out and
> system hang) on an Exynos5420 Peach Pit Chromebook and an Exynos5800
> Peach Pi Chromebok which both have the same dw_mmc 250A IP version.
>
> Unfortunately $subject doesn't seem to be enough since even with that
> applied I got:
>
> [ 4.264418] mmc_host mmc1: Timeout sending command (cmd 0x202000
> arg 0x0 status 0x80202000)
> [ 4.283988] random: nonblocking pool is initialized
> [ 28.054406] INFO: rcu_sched detected stalls on CPUs/tasks:
> [ 28.058412] 0: (5 ticks this GP) idle=65f/140000000000001/0
> softirq=215/216 fqs=39
> [ 28.066129] (detected by 1, t=4765 jiffies, g=-294, c=-295, q=2)
> [ 28.072202] Task dump for CPU 0:
> [ 28.075412] kworker/u16:0 R running 0 6 2 0x00000002
> [ 28.081749] Workqueue: kmmcd mmc_rescan
> [ 28.085570] [<c04c2698>] (__schedule) from [<00000000>] ( (null))
> [ 28.091724] rcu_sched kthread starved for 796 jiffies!
>
>>>>>>
>>>>>> +static bool dw_mci_wait_busy(struct dw_mci *host)
>>>>>> +{
>>>>>> + unsigned long timeout;
>>>>>> +
>>>>>> + if (host->verid < DW_MMC_250A)
>>>>>> + return true;
>>>>>> +
>>>>> I wonder this might be true for 240A as well.
>>>> Odroid-U3 board with Exynos4412 and MMC 240A does not have this problem.
>>>> On the other side busy check does not hurt it anyway.
>
> This problem also does not happen on an Exynos5250 Snow Chromebook
> which has a dw_mmc IP version 241A.
>
>>> Which kernel version do you use?
>>> I also have the exynos5422 board, but i didn't find the below error yet.
>>> It doesn't relate with IP version.
>>> If you share your environment, i can check with exynos5422 board.
>>
>> linux-next on odroid-xu3. With MMC card removed, booting from sdcard.
>> Please also note that broken-cd quirk is on in dts.

I can't find this problem on exynos5422 board.(Odroix-xu3)
Could you share the properties into dts file?

Best Regards,
Jaehoon Chung

>>
>
> I tested by trying to add wifi support to the Peach Pit/Pi Chromebooks
> which have an SDIO wifi chip attached to mmc@12210000. This [0] is the
> patch I've on top of linux-next fwiw.
>
>>>
>>> I'm not sure but this patch could be dropped.
>>> Because this patch is just only checking whether card is busy or not.
>>>
>>> this patch(mmc:dw_mmc: fix bug that case 'timeout sending command') can cover your patch.
>>
>> I will test it.
>>
>
> I tested it and although the mentioned patch does fix the mmc commands
> send timing out, now card detection seems to not be working since the
> kernel keeps waiting for aiting for root device /dev/mmcblk1p4...
>
> and the this error is shown:
>
> [ 4.249434] dwmmc_exynos 12210000.mmc: Data busy (status 0x306)
>
> So I tried the other patch from Addy's series "mmc: dw_mmc: Don't
> start command while data busy" but it did not have an effect. I still
> see the data busy error and the uSD card is not detected.
>
> Best regards,
> Javier
>
> [0]: http://paste.debian.net/plain/145877
>