On 2017-05-17 11:02, Fabio Estevam wrote:

Hi Haibo,

On Tue, May 16, 2017 at 11:10 PM, Bough Chen [off-list ref] wrote:

quoted

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