[U-Boot] [RFC] mmc: fsl_esdhc: Do not set high speed mode on MX25 and MX51

[Benoît Thébaudeau]

Hi Fabio,

On Fri, Oct 20, 2017 at 8:40 PM, Fabio Estevam <festevam at gmail.com> wrote:
> On Fri, Oct 20, 2017 at 10:40 AM, Benoît Thébaudeau <benoit at wsystem.com> wrote:
>
>> With mainline U-Boot on my board, normal-speed SD cards work fine, but not HS
>> ones. Both types of cards work fine at 48 MHz with my custom and older U-Boot.
>
> Ok, great! What is the version of your old U-Boot?

2012.07. I know, _very_ old.

About the drive strength, the CSI pads used on my board for eSDHC2
have their drive strength set to nominal after POR, and I had to set
it to high in order to make HS work, whereas the SD1 pads used on
mx25pdk for eSDHC1 already have their default drive strength set to
high, so setting it to max as I previously suggested should not be
needed, unless the routing of the board requires it and there are also
errors in Linux that are just silently recovered.

>> The main difference seems to be the management of SD timeouts. I will try to
>> track the differences until I find the root cause. The test results in PIO mode
>> might also give some clues.
>
> Thanks for the investigation!

I already have a mainline version working at HS with changes only in
fsl_esdhc.c (apart from the port of my board). I still have to narrow
these changes down to the issue.

Is it mainline Linux that you have tested?

Best regards,
Benoît