[U-Boot] [PATCH v3 2/2] ppc4xx: Add PPC4xx SPI helpers to Sequoia

Steven A. Falco
2008-12-09T20:38:55Z

Ben Warren wrote:
>
> Hi Wolfgang,
>
> Wolfgang Denk wrote:
>> Dear Ben Warren,
>>
>> In message <493EA876.7090008@gmail.com> you wrote:
>>
>>> Why not enable this feature on Sequoia? Wolfgang's argument for
>>> keeping the patch out then goes away. IMHO, eval boards should have
>>> as many options enabled by default as possible, and the user then has
>>> the option to opt out.
>>>
>>
>> But there is not a single SPI device on the Sequoia board, and if you
>> attach one, you have to write driver code for it that implements the
>> chip select handling and the specific device protocol. We would have
>> a driver included, without any "users" (code that actually calls
>> these functions).
>>
>>
> Sure. Ignorant assumption on my part that the eval board had something
> like a SPI EEPROM, but it looks like there's just a header. In that
> case, the only advantage to including it is to ensure the driver keeps
> up with any API changes.
>> In other words, this driver is a prerequisite for other SPI device
>> drivers that might follow later, but as is, it's just a waste of
>> memory.
>>
>> It would just waste memory to enable it.
>>
>>
> OK, but who cares about memory on an evaluation board? Their entire
> raison-d'etre is to serve as a starting point for custom boards. I know
> if I was building a board with this CPU and planned on using SPI, it
> would be much nicer if the driver was included than having to search the
> message boards. Just my 2c.

I agree with this position. I use U-Boot for two purposes - booting a
kernel, and experimenting with hardware. Given that I am currently
in the design phase of a project, I am prototyping things on an evaluation
board, to see what works and what doesn't. Having U-Boot support all the
interfaces of a SOC like the PPC440EPx is very useful to me. Much easier
and quicker to do prototyping in U-Boot than in Linux.

But again, you guys can decide the philosophical issues. I'm just the code
monkey...

Steve

>> Best regards,
>>
>> Wolfgang Denk
>>
>>
> regards,
> Ben
>