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

Andrzej Hajda
2015-02-13T08:13:55Z

On 02/13/2015 08:30 AM, Jaehoon Chung wrote:
> 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?

It is just linux-next with exynos_defconfig and
arch/arm/boot/dts/exynos5422-odroidxu3.dts, without changes:
...
&mmc_0 {
status = "okay";
mmc-pwrseq = <&emmc_pwrseq>;
broken-cd;
card-detect-delay = <200>;
samsung,dw-mshc-ciu-div = <3>;
samsung,dw-mshc-sdr-timing = <0 4>;
samsung,dw-mshc-ddr-timing = <0 2>;
pinctrl-names = "default";
pinctrl-0 = <&sd0_clk &sd0_cmd &sd0_bus4 &sd0_bus8>;
bus-width = <8>;
cap-mmc-highspeed;
};
...

Regarding hardware:
eMMC card removed,
booting from sdcard.

Regards
Andrzej

>
>
> 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
>>
>