On Wed, Nov 08, 2017 at 08:57:52PM +0000, Mark Brown wrote:

On Wed, Nov 08, 2017 at 08:49:55PM +0000, Levin, Alexander (Sasha Levin) wrote:

...

From: Jiada Wang jiada_wang@mentor.com

[ Upstream commit 66459c5a50a787c474b734b586328f7111ab6df0 ]

Previously DMA watermark level is configured to fifosize/2, DMA mode can be used only when transfer length can be divided by 'watermark level * bpw', which makes DMA mode not pratical.

This patch adjusts watermark level to largest number (no bigger than fifosize/2) which can divide 'tranfer length / bpw' for each transfer.

This seems like an optimization not a bug fix...

Hm, is it? I read it as "DMA is not being used at all even though we thought we're using it".

Yes, the impact is "just" performance, but doesn't it result in quite a significat impact?