On 05/06/2015 02:30 PM, zhangfei wrote:
>
>
> On 05/06/2015 12:21 PM, Jaehoon Chung wrote:
>> 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@xxxxxxxxxxx> 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?
> If non-removable is not set, broken-cd has to be set.
> Or set both, but usually we may not consider this at first.
>
> When we first want to enable emmc, we naturally use non-removable, according to Documentation/devicetree/bindings/mmc/mmc.txt
Why do you use naturally non-removable? eMMC can be removed at some SoC. (It's assumption.)
Is it common approach that consider how eMMC can be detected at host controller?
> 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.
>
> But unfortunately we find it does not work and took half day to debug, happen to find broken-cd can work, though mmc_rescan is keeps running for a while, and we treat it as workaround.
>
> After some time, another person find broken-cd does not make sense, and debug again about non-removable, and took another half day.
>
> It really happens here :(
Sorry for not saving your time.
Hmm..To prevent your case, it seems better that apply your patch. :)
Will apply at my dw-mmc tree.
Thanks!
Best Regards,
Jaehoon Chung
>
> So is it better support just using non-removable for emmc, aligning with mmc.txt.
>
>> 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.
>>
>
> Thanks
>
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