On 7 November 2016 at 11:03, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> On Fri, Nov 4, 2016 at 6:32 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>
>> In the eMMC 4.51 version of the spec, an EXT_CSD field called
>> GENERIC_CMD6_TIME[248] was added. This allows cards to specify the maximum
>> time it may need to move out from its busy state, when a CMD6 command has
>> been sent.
>>
>> In cases when the card is compliant to versions < 4.51 of the eMMC spec,
>> obviously the core needs to use a fall-back value for this timeout, which
>> currently is set to 10 minutes. This value is completely in the wrong range
>> and importantly in some cases it causes a card initialization to take more
>> than 10 minute to complete.
>>
>> Earlier this scenario was avoided as the mmc core used CMD13 to poll the
>> card, to find out when it stopped signaling busy. Commit 08573eaf1a70
>> ("mmc: mmc: do not use CMD13 to get status after speed mode switch")
>> changed this behavior.
>>
>> Instead of reverting that commit, which would cause other issues, let's
>> instead start by picking a simple solution for the problem, by using a
>> 500ms default generic CMD6 timeout.
>>
>> The reason for using exactly 500ms, comes from observations that shows it's
>> quite common for cards to specify 250ms. 500ms is two times that value so
>> likely it should be enough for most cards.
>>
>> Cc: <stable@xxxxxxxxxxxxxxx> # v4.8+
>> Fixes: 08573eaf1a70 ("mmc: mmc: do not use CMD13 to get status after speed
>> mode switch")
>> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>
> This fixes my rootfs issue. It still doesn't appear immediately as it did
> before, but maybe before was wrong then. (Or we should hammer
> a bit with CMD13 and wait for a correct CRC?)
Yes, I see this as a quick fix for stable/rc.
So, I intend to submit a new series which builds on top of this and
which hopefully will improves the behaviour.
>
> Anyways: things are a lot better now, so:
> Tested-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Thanks for testing!
Kind regards
Uffe
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