[PATCH 1/3] spi/qspi: Add memory mapped read support.

[Sourav Poddar]

On Friday 18 October 2013 11:26 AM, Trent Piepho wrote:
> On Thu, Oct 17, 2013 at 9:06 PM, Sourav Poddar<sourav.poddar at ti.com>  wrote:
>> On Friday 18 October 2013 05:12 AM, Mark Brown wrote:
>>>> Are you looking for comparison between  read_via_dma() v/s memcpy() ?
>>> No, I'm looking for a comparison of normal SPI mode (which I'd have
>>> expected to DMA) and the memcpy() mode.
>>>
>>>> If yes, then unfortunately we are bit constrained because our controller
>>>> does not support DMA. So, we have to depend on CPU based memcpy()
>>>> only. However, use of DMA can be added as an independent patch on
>>>> top of this CASE-2 patch.
>>> However if the controller can't DMA at all then that's not going to be
>>> possible...  am I understanding you correctly that normal SPI can't DMA?
>> Yes, you are correct, the normal SPI cant DMA.
> Hardware limitation or driver limitation?  Adding DMA support to the
> driver might be much more useful than adding memory mapped read
> support.
Its a hardware limitation, the qspi controller does not support DMA.