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?)
Anyways: things are a lot better now, so:
Tested-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Yours,
Linus Walleij
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