Re: [PATCH] mmc: dw_mmc: dw_mci_get_cd check MMC_CAP_NONREMOVABLE

[Jaehoon Chung <jh80.chung@samsung.com>]

Hi, Zhangfei.

On 05/06/2015 11:16 AM, zhangfei wrote:
> 
> 
> On 05/06/2015 09:39 AM, Jaehoon Chung wrote:
>> Hi,
>>
>> On 05/06/2015 10:33 AM, zhangfei wrote:
>>>
>>>
>>> On 05/06/2015 09:26 AM, Jaehoon Chung wrote:
>>>> Hi,
>>>>
>>>> On 05/06/2015 10:14 AM, Zhangfei Gao wrote:
>>>>> On 6 May 2015 at 08:36, Jaehoon Chung <jh80.chung@samsung.com> wrote:
>>>>>> Hi, Zhangfei.
>>>>>>
>>>>>> If you want to check it, use the "broken-cd" and "non-removable" properties into dt-file.
>>>>>> Did you use them?
>>>>>
>>>>> Yes.
>>>>> "broken-cd" can work, but mmc_rescan keeps running.
>>>>> "non-removable" does NOT work, which should be used for emmc.
>>>>> Since dw_mci_get_cd only checks DW_MCI_QUIRK_BROKEN_CARD_DETECTION, so
>>>>> only checks "broken-cd" but not check "non-removable"
>>>>
>>>> Did you use the usage like the below..
>>>>
>>>> dwmmc0 {
>>>>      non-removable;
>>>>      broken-cd;
>>>> };
>>>
>>> non-removable and broken-cd should be used only one.
>>
>> Did you check the code?
>> If non-removable is set, broken-cd should be discarded.
>>
>> I think that the below usage is not "must not".
> 
> I understand you meaning, you suggest
>>>> dwmmc0 {
>>>>      non-removable;
>>>>      broken-cd;
>>>> };
> 
> drivers/mmc/host/dw_mmc.c checks broken-cd, while mmc_of_parse checks non-removable.
> Yes, it works.
> 
> But is it a workaround? and a little tricky.
> It costs me some time to find why non-removable does not work, someone else may meet the same issue.
> It does not align with Documentation/devicetree/bindings/mmc/mmc.txt, which is the guideline to write dts.
> And see drivers/mmc/host/sdhci.c: sdhci_do_get_cd, it also checks both.

"non-removable" is assumed that card is not removed.
it's not also correct detect scheme. Then it's also able to say the broken card detection scheme.
(if CDETECT register can't use.)

BROKEN_CARD_DETECTION quirk means that it has unreliable card detection.
When dw-mmc host controller has unreliable card detection scheme, it could be set.
Is this tricky? i don't think so.

Though non-removable doesn't set, it has to work fine, isn't?
And i don't think that dw-mmc controller must use it since sdhci controller used.
(I have known that sdhci controller is using that.)

Well, If Ulf thinks this is tricky, i will consider this patch.

Best Regards,
Jaehoon Chung
> 
> Thanks
> 
> 
>>
>> Best Regards,
>> Jaehoon Chung
>>
>>>
>>> Documentation/devicetree/bindings/mmc/mmc.txt
>>> Card detection:
>>> If no property below is supplied, host native card detect is used.
>>> Only one of the properties in this section should be supplied:
>>>    - broken-cd: There is no card detection available; polling must be used.
>>>    - cd-gpios: Specify GPIOs for card detection, see gpio binding
>>>    - non-removable: non-removable slot (like eMMC); assume always present.
>>>
>>> work
>>>   dwmmc0 {
>>>       broken-cd;
>>>   };
>>>
>>> NOT work
>>>   dwmmc0 {
>>>       non-removable;
>>>   };
>>>
>>> Thanks
>>>
>>
>