[U-Boot] fsl mx28evk spi nor probe problem

[Sinan Akman]

On 11/22/2012 08:33 PM, Fabio Estevam wrote:
> Hi Sinan,
>
> On Thu, Nov 22, 2012 at 7:43 PM, Sinan Akman <sinan at writeme.com> wrote:
>>
>>    Hi Fabio
>>
>>    I just tried spi nor on fsl m28evk and see :
>>
>>    MX28EVK U-Boot > sf probe
>>    SF: Unsupported manufacturer ff
>>    Failed to initialize SPI flash at 2:0
>>
>>    This is with U-Boot 2012.10 and I included
>> #define CONFIG_SPI_FLASH_WINBOND in mx28evk.h.
>
> Which SPI flash have you populated into mx28evk?

   Hi Fabio, thanks for your reply. I guess I got
blindfolded by another winbond W25X80 populated
board that I used to access and now an unrelated
winbond chip on this board. But this board was not
populated therefore the FF readings as ID. Marek
helped me to figure out and forwarded your message.

   I find it interesting though that an unpopulated chip
returns FFs instead of causing a timeout etc. Probing
another (presumably non-existing) bus/cs value (e.g. 3:0)
causes a timeout. I don't know enough about this at
this point why we read FFs quietly in an unpopulated case
but I would like to dig a bit more.

   Thanks much for the pointers you provided.

   -- sinan