Hi Ulf,
On Mon, Jan 16, 2017 at 11:13 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> On 16 January 2017 at 04:48, Dong Aisheng <dongas86@xxxxxxxxx> wrote:
>> Hi Ulf,
>>
>> On Fri, Jan 13, 2017 at 7:05 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>>> Regressions for not being able to detect an eMMC HS DDR mode card has been
>>> reported for the sdhci-esdhc-imx driver, but potentially other sdhci
>>> variants may suffer from the similar problem.
>>>
>>> The commit e173f8911f09 ("mmc: core: Update CMD13 polling policy when
>>> switch to HS DDR mode"), is causing the problem. It seems that change moved
>>> one step to far, regarding changing the host's timing before polling for a
>>> busy card.
>>>
>>> To fix this, let's move back to the behaviour when the host's timing is
>>> updated after the polling, but before the switch status is fetched and
>>> validated.
>>>
>>> In cases when polling with CMD13, we keep validating the switch status at
>>> each attempt. However, to align with the other card busy detections
>>> mechanism, let's fetch and validate the switch status also after the host's
>>> timing is updated.
>>>
>>> Reported-by: Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>
>>> Reported-by: Gary Bisson <gary.bisson@xxxxxxxxxxxxxxxxxxx>
>>> Fixes: e173f8911f09 ("mmc: core: Update CMD13 polling policy when switch..")
>>> Cc: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
>>> Cc: Dong Aisheng <aisheng.dong@xxxxxxx>
>>> Cc: Haibo Chen <haibo.chen@xxxxxxx>
>>> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>>
>> Thanks for the fix.
>>
>> Reviewed-by: Dong Aisheng <aisheng.dong@xxxxxxx>
>
> Thanks for reviewing!
>
>>
>> BTW, i wonder if we could then remove the CMD13 Polling method or give a
>> temporarily WARN_ONCE to indicate OBSOLETED using and force all hosts
>> to provide card_busy() callback.
>> Then we can permanently fix the potential timing mismatch issue.
>
> In the end it seems like the issue is host specific. I have
> successfully used CM13 polling on my ux500 board (mmci.c, with some
> hacks to force CMD13).
>
> If we see any further issues, perhaps we should invent a new host cap,
> which forbids the CMD13 polling and then those host drivers that has
> issues, can set it. Wouldn't that be okay for you?
>
I'm fine with it.
Thanks
Regards
Dong Aisheng
> [...]
>
> Kind regards
> Uffe
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