Re: [PATCH] mmc: dw_mmc: Fix occasional hang after tuning on eMMC

[Enric Balletbo Serra]

Hi,

Missatge de Doug Anderson <dianders@xxxxxxxxxxxx> del dia dt., 9 de
jul. 2019 a les 18:38:
>
> Hi,
>
> On Tue, Jul 9, 2019 at 2:07 AM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
> >
> > On Tue, 9 Jul 2019 at 00:48, Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
> > >
> > > In commit 46d179525a1f ("mmc: dw_mmc: Wait for data transfer after
> > > response errors.") we fixed a tuning-induced hang that I saw when
> > > stress testing tuning on certain SD cards.  I won't re-hash that whole
> > > commit, but the summary is that as a normal part of tuning you need to
> > > deal with transfer errors and there were cases where these transfer
> > > errors was putting my system into a bad state causing all future
> > > transfers to fail.  That commit fixed handling of the transfer errors
> > > for me.
> > >
> > > In downstream Chrome OS my fix landed and had the same behavior for
> > > all SD/MMC commands.  However, it looks like when the commit landed
> > > upstream we limited it to only SD tuning commands.  Presumably this
> > > was to try to get around problems that Alim Akhtar reported on exynos
> > > [1].
> > >
> > > Unfortunately while stress testing reboots (and suspend/resume) on
> > > some rk3288-based Chromebooks I found the same problem on the eMMC on
> > > some of my Chromebooks (the ones with Hynix eMMC).  Since the eMMC
> > > tuning command is different (MMC_SEND_TUNING_BLOCK_HS200
> > > vs. MMC_SEND_TUNING_BLOCK) we were basically getting back into the
> > > same situation.
> > >
> > > I'm hoping that whatever problems exynos was having in the past are
> > > somehow magically fixed now and we can make the behavior the same for
> > > all commands.
> > >
> > > [1] https://lkml.kernel.org/r/CAGOxZ53WfNbaMe0_AM0qBqU47kAfgmPBVZC8K8Y-_J3mDMqW4A@xxxxxxxxxxxxxx
> > >
> > > Fixes: 46d179525a1f ("mmc: dw_mmc: Wait for data transfer after response errors.")
> > > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > > Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> > > Cc: Alim Akhtar <alim.akhtar@xxxxxxxxx>
> > > Cc: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
> > > ---
> > > Marek (or anyone else using exynos): is it easy for you to test this
> > > and check if things are still broken when we land this patch?  If so,
> > > I guess we could have a quirk to have different behavior for just
> > > Rockchip SoCs but I'd rather avoid that if possible.
> > >
> > > NOTE: I'm not hoping totally in vain here.  It is possible that some
> > > of the CTO/DTO timers that landed could be the magic that would get
> > > exynos unstuck.
> >
> > I have eMMC module attached to Odroid U3 (Exynos4412,
> > samsung,exynos4412-dw-mshc). What is the testing procedure? With your
> > patch it boots fine:
> > [    3.698637] mmc_host mmc1: Bus speed (slot 0) = 50000000Hz (slot
> > req 52000000Hz, actual 50000000HZ div = 0)
> > [    3.703900] mmc1: new DDR MMC card at address 0001
> > [    3.728458] mmcblk1: mmc1:0001 008G92 7.28 GiB
>
> To really test it, it'd be nice to see some HS200 eMMC cards enumerate
> OK.  Specifically the patch adjusts the error handling and the place
> where that happens mostly is during tuning.
>
> I'll also try to find some time today to check a peach_pit or a
> peach_pi.  I think I saw one in the pile near my desk so if it isn't
> in too bad of a shape I can give mainline a shot on it.
>

I did a normal boot on peach_pi [1] and odroidxu3 [2] with that patch
applied, and the eMMC attached on both was detected as

 [    2.294798] mmc0: new HS400 MMC card at address 0001

I can do some stress tests tomorrow on those boards if that helps.

Cheers,
~ Enric

[1] https://storage.kernelci.org/chrome-platform/for-kernelci/ib-mfd-cros-v5.3-87-g0fe7e9d7d5a3/arm/multi_v7_defconfig/gcc-8/lab-collabora/boot-exynos5800-peach-pi.html
[2] https://storage.kernelci.org/chrome-platform/for-kernelci/ib-mfd-cros-v5.3-87-g0fe7e9d7d5a3/arm/multi_v7_defconfig/gcc-8/lab-collabora/boot-exynos5422-odroidxu3.html

> -Doug
>
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