[PATCH] spi: spi-mem: ease checks in dtr_supports_op()

[Jagan Teki]

On Thu, Oct 20, 2022 at 2:04 PM Dhruva Gole <d-gole at ti.com> wrote:
>
> Remove the extra conditions that cause some cases to fail prematurely
> like if the data number of bytes is odd. The controller can handle odd
> number of bytes data read in DTR Mode. Don't fail supports op for this
> condition.
>
> Signed-off-by: Dhruva Gole <d-gole at ti.com>
> ---
>
> For a deeper context, refer to a cover letter from an earlier patch
> series:
> https://lore.kernel.org/u-boot/20221019064759.493607-1-d-gole@ti.com/T/#m3fd93bdcc30b3b5faada6abe45a4104388afc300
> Here, I am trying to boot from OSPI Flash present on board the AM62-SK
> EVM. However, despite enabling the necessary configs and DT nodes, my
> boot flow seemed to be failing. I then came to know that the condition
> causing this failure was that my generated DTB was of odd number of
> bytes.
> So, while loading the dtb from the Octal SPI NOR Flash to the memory,
> the data.nbytes was odd which made the supports_op
> function return false. This check feels a little too strict at the
> spi-mem stage and we should let the controller decide what to do in case
> of odd bytes in DTR. After applying this patch, I was able to
> succesfully boot the AM62SK EVM without any issues.
>
> I would also like to justify this patch by pointing the community to the
> equivalent code in the linux kernel, in drivers/spi/spi-mem.c, where this check
> is absent as well.
>
> The controller does work with odd number of bytes and I have not seen
> any sort of bugs in the absence of this supports_op check. Hence, feel
> that it is safe enough to discard this check from here.

Require better wrapup of above text to be part of commit body.