Re: [PATCH AUTOSEL for-4.9 04/53] spi: imx: adjust watermark level according to transfer length

From: Mark Brown
Date: Wed Nov 08 2017 - 18:11:20 EST


On Wed, Nov 08, 2017 at 10:48:14PM +0000, Levin, Alexander (Sasha Levin) wrote:
> On Wed, Nov 08, 2017 at 10:11:02PM +0000, Mark Brown wrote:

> >expose problems if we start using it. If you look at the history of the
> >driver there's some quirks were added later on for example, and I didn't
> >check the DMA controller drivers or anything and obviously can't see any
> >out of tree code users may have.

> I'm considering these commits to be on the safer side because they're
> much older than the ones Greg usually grabs. There were no upstream
> fixes to this commit for 10 months now, and given the code changes
> upstream in that subsystem, this patch seemed to be safe to backport.

Like I say I'm seeing some potentially relevant variant handling added
later and you also have to consider the DMA drivers it might be used
with (imx-dma looks safe but perhaps there's other things, never mind
out of tree code). It just doesn't feel good.

We have also had problems in the past with SPI performance enhancements
exposing exising problems elsewhere though not so much with this sort of
area so I'm less worried about that.

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