Re: [PATCH v2 5/6] spi: davinci: do not use DMA if transfer length is less than 16

[Arnd Bergmann <arnd@xxxxxxxx>]

On Fri, Feb 17, 2017 at 5:43 PM, Frode Isaksen <fisaksen@xxxxxxxxxxxx> wrote:
> On 17/02/2017 17:37, Arnd Bergmann wrote:
>> On Fri, Feb 17, 2017 at 11:38 AM, Frode Isaksen <fisaksen@xxxxxxxxxxxx> wrote:
>> 16 seems low as the cutoff. Have you found this experimentally and
>> tested that for e.g. 32
>> bytes there is actually an advantage in using DMA?
> Yes, I have tested for different sizes. Actually 32 bytes is better @30MHz, but if the bit rate goes down, DMA wins over PIO. Do you prefer 32 bytes ?

No, I don't care about the specific value, just making sure that you had
actually tested this, as I had expected PIO to be faster here.

     Arnd
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