Re: [RFC PATCH 1/4] spi: spidev: Add Google SPI flash compatible string

Javier Martinez Canillas
2015-05-20T11:21:53Z

Hello Mark,

On 05/20/2015 12:37 PM, Mark Brown wrote:
> On Wed, May 20, 2015 at 12:18:13PM +0200, Javier Martinez Canillas wrote:
>> On 05/20/2015 12:13 PM, Mark Brown wrote:
>
>> > This is adding a binding with no documentation, documentation is
>> > mandatory for all bindings.
>
>> Yes, I missed... sorry about that. Do you agree with the approach
>> though so I can re-spin the patches adding the missing DT binding?
>
> It's probably OK but I didn't really drill through since the binding was
> missing. If these parts are commodity as described it seems surprising
> that they aren't compatible with any existing kernel driver.
>

The ChromeOS user-space just uses flashrom to send a raw stream of bytes
via spidev to the SPI NOR flash chip. There is drivers/mtd/spi-nor/spi-nor.c
but AFAIU there are some limitations when interfacing the flash through
the MTD layer, for example there isn't a way to set the SPI flash write
protection through MTD. But I'll do some investigation before re-spinning
the patches.

BTW, the other "rohm,dh2228fv" compatible string in spidev added by commit
8fad805bdc52 ("spi: spidev: Add Rohm DH2228FV DAC compatible string"), also
does not have a documented DT binding so that should be fixed as well.

Best regards,
Javier