imx7: mmc_select_hs200 failed, error -74

[stefan@agner.ch (Stefan Agner)]

On 2017-05-17 11:02, Fabio Estevam wrote:
> Hi Haibo,
> 
> On Tue, May 16, 2017 at 11:10 PM, Bough Chen <haibo.chen@nxp.com> wrote:
> 
>> Hi Fabio,
>>
>> Can you open the mmc debug and show the full log?
>> By the way, you should first make sure whether the eMMC chip you used support HS200, and double
>> check whether the vccq voltage is 1.8v or 1.2v, HS200 mode can't work on 3.3v I/O voltage.
> 
> The imx7s warp board supplies 3.15V to VCCQ eMMC pins, so it cannot
> work in HS200 mode as you said.
> 
> In this case it should still be able to work in DDR52 mode though.

Maybe I missed something, but shouldn't that all be part of the device
tree these days?

E.g. mark that it is only 3.3V capable (no-1-8-v) and maybe other
capabilities (see Documentation/devicetree/bindings/mmc/mmc.txt).

> 
> Please see the patch I sent:
> http://marc.info/?l=linux-mmc&m=149495763808805&w=2

Afaict, the hardware tries to use whatever is the greatest common
denominator... If the board has restrictions, they should be specified
in the DT, and the driver should respect them.

--
Stefan