Odroid-C1 regression with commit 4bc31edebde5 ("mmc: core: Set HS clock speed before sending HS CMD13")

[Ulf Hansson]

On Mon, 19 Jun 2023 at 21:54, Martin Blumenstingl
<martin.blumenstingl at googlemail.com> wrote:
>
> Hi Ulf,
>
> On Wed, Jun 14, 2023 at 5:49 PM Ulf Hansson <ulf.hansson at linaro.org> wrote:
> [...]
> > > Full register dump:
> > > # cat /sys/kernel/debug/regmap/c1108e00.mmc/registers
> > > 00: 00000900
> > > 04: 0000004d
> > > 08: e7ffe002
> > > 0c: 02f0003f
> > > 10: 0003f009
> > > 14: 03b81c00
> > > 18: 2c43bcf0
> > > 1c: e0000150
> > > 20: 00000000
> > > 24: 00003067
> > > 28: 00000000
> > > 2c: 00000000
> > > 30: 00000000
> > > 34: 00fe0cff
> > > 38: 0000100b
> > >
> > > In case you are curious, the driver is: drivers/mmc/host/meson-mx-sdhc-mmc.c
> >
> > Thanks for sharing this data!
> >
> > I assume the above registers indicate that we have sent the command
> > and are now waiting for an IRQ for a response/error, but we never
> > receive one.
> >
> > To really figure out what is going on, I think we need to do some
> > additional low level debugging/testing.
> >
> > I was looking at the commit message from e4bf1b0970ef ("mmc: host:
> > meson-mx-sdhc: new driver for the Amlogic Meson SDHC host"), which
> > indicates that the clock management is quite limited for this HW. For
> > example, the 51000000Hz isn't one of the supported frequencies. Could
> > that be the reason for the problem? Perhaps if we play with changing
> > the frequency to something that is considered supported - then can we
> > make this work?
> You seem to be more familiar with this Amlogic MMC controller than I am ;-)

Sometimes a well written commit message actually helps. :-)

> Today I finally had some time for testing and when I started Ziyang
> Huang provided a patch [0] (admittedly: I think it needs to be
> improved, but finally we know that it's a MMC controller driver
> limitation and not an MMC core bug)

Great news!

I will continue to monitor the thread and defer to apply anything
until you have given it your blessing, of course.

Kind regards
Uffe