[PATCH v2] spi: add spi_tegra driver

[Grant Likely]

On Fri, Aug 27, 2010 at 1:26 PM, Erik Gilling <konkers at android.com> wrote:
> On Wed, Aug 25, 2010 at 2:22 PM, Erik Gilling <konkers at android.com> wrote:
>>> As an aside, and commenting on the tegra DMA api... Is the IS_ERR()
>>> pattern in the tegra_dma_allocate_channel() return really a good idea
>>> here?  Personally I find that pattern isn't very useful, especially
>>> when the results is either "yes, allocated" or "no, not-alocated", and
>>> it is very easy to write code that tests the wrong thing on the return
>>> value because the compiler cannot catch it.  In other words, if it
>>> isn't vital to return a specific error code, the using the PTR_ERR()
>>> pattern adds unnecessary risk to the code because developers are used
>>> to seeing and writing this pattern:
>>>
>>> tspi->rx_dma = tegra_dma_allocate_channel(TEGRA_DMA_MODE_ONESHOT);
>>> if (!tspi->rx_dma)
>>>        return -ENOMEM;
>>>
>>> The compiler won't catch it if the return value is an PTR_ERR.
>>>
>>> (I know that some subsystems make heavy use of it, particularly
>>> filesystems and the block layer which do need to return specific error
>>> codes to userspace.  My argument is that the specific error code is
>>> probably irrelevant when allocating DMA channels)
>>
>> I don't have a strong opinion either way but that's the way Colin's
>> code is written.  I'll let him speak to that.
>
> I spoke with colin about this.  He's fine getting rid of the PTR_ERR.
> I'll post a DMA and SPI patch when that's done.

Okay, thanks.

g.