[U-Boot] [PATCH RESEND-WITH-JUSTIFICATION] spi: soft_spi: Support NULL din/dout buffers

[Jagan Teki]

On Fri, Apr 11, 2014 at 12:47 AM, Andrew Ruder <andy at aeruder.net> wrote:
> On Fri, Apr 11, 2014 at 12:33:45AM +0530, Jagan Teki wrote:
>> >> It would be great if you mentioned issue scenario for status poll case
>> >> drivers/mtd/spi/sf_ops.c:               ret = spi_xfer(spi, 8, NULL,
>> >> &status, 0);
>> OK - means issue only with soft_spi.c is it?
>
> Yes, and a couple other drivers.
>
>> Can you share the issue log or typical use case scenario w.r.t soft_spi.c,
>> I need to understand how this got resolved with your change.
>
> Yes, you actually posted one such case that will not work "correctly"
> with soft_spi.  In the line of code you posted above, soft_spi will
> actually perform a read from address 0x0.  In most cases, the read side
> isn't a huge deal, but on the write side it can cause all kinds of
> surprises.
>
>> I understand you assigned '0' when dout is NULL and you took the buf
>> only when din is !NULL.
>
> Yes, just handling NULL case to be how most drivers are handling it and
> how apparently most users of the spi modules (like mtd/spi/sf_ops) are
> clearly expecting it to work.

I saw some check-patch issues, can you fix - plan to apply.

thanks!
-- 
Jagan.