[PATCH] Revert "mmc: disable UHS modes if Vcc cannot be switched on and off"

Pali Rohár pali at kernel.org
Tue Aug 11 18:27:23 CEST 2020

On Tuesday 11 August 2020 21:33:19 Faiz Abbas wrote:
> Pali,
> On 11/08/20 1:19 pm, Pali Rohár wrote:
> > On Tuesday 11 August 2020 08:39:24 Faiz Abbas wrote:
> >> Pali, Peng,
> >>
> >> On 10/08/20 6:25 am, Peng Fan wrote:
> >>> Faiz, Jean
> >>>
> >>>> Subject: [PATCH] Revert "mmc: disable UHS modes if Vcc cannot be switched
> >>>> on and off"
> >>>
> >>> Got time to take a look?
> >>>
> >>
> >> When this issue was reported in the last thread, Pali said that he was unable to get
> >> prints because of the constant reboot loops? Shouldn't it be easy to put while(1)
> >> at different points in this execution and see which step causes the reboot loop?
> > 
> > In May in that last thread I wrote details which I was able to gather:
> > 
> >     Month ago I was able to detect that problem is somewhere in function
> >     mmc_set_ios() from mmc.c file. I put long debug line prior and also
> >     after mmc_set_ios() call. And it was printed only prior. Not after.
> >     So I think NULL pointer dereference is in mmc_set_ios() function.
> > 
> > I could try with that while(1) loop to print detailed log message and
> > read/capture it. But what information for debugging you need? Or what do
> > you want to print which could help you?
> > 
> You can continue to bisect into omap_hsmmc_set_ios() to see at what point the NULL pointer
> gets triggered and what the NULL pointer is.

I could try it, but I do not think I would be able to gather more data.
I will try to find free time for this debugging on device either at the
end of this week or end of next week.

As I wrote in previous thread, main issue which makes it hard to debug
is that this error is not triggered in emulator.

> Also can you point to your config file?

I'm using standard config file without any modifications. It is:

In case you are interested, I'm compiling u-boot by commands:

export ARCH=arm
export CROSS_COMPILE=arm-linux-gnueabi-
make nokia_rx51_config
make -j12 u-boot.bin

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