[U-Boot] spi flash env and driver model

[Chris Packham]

On Mon, Aug 7, 2017 at 10:31 PM, Chris Packham <judge.packham at gmail.com> wrote:
> Hi,
>
> I'm looking at a problem on the db-88f6820-amc board (which has it's
> env on spi flash). Somewhere in the init sequence we get a crash.
>
> git bisect leads me to commit 8fee8845e7 ("enf_sf: reuse
> setup_flash_device instead of open coding it") but I don't think
> that's actually the problem. The real problem seems to be the way
> setup_spi_device() relies on the speed to come from the device-tree.
> Even when I specify a speed for the spi-flash in the device tree it
> doesn't seem to stick. The only thing that seems to work is restoring
> the CONFIG_ENV_SPI_MAX_HZ in the DM_SPI_FLASH case.
>
> I can submit that as a patch but it seems contrary to the intentions
> of commit 96907c0fe5 ("dm: spi: Read default speed and mode values
> from DT").
>
> Does anyone have any thoughts as to where to go with this?

So now I've actually been able to see the failure with an ICD attached
the problem is a divide by 0 in mvebu_spi_set_speed() because the
speed is being passed down as 0. Moving up the stack this appears to
be coming from the parent_platdata looked up by spi_get_bus_and_cs().
So it looks like the spi-max-frequency property hasn't been parsed up
from the device tree prior to this call.