linux-kernel - Re: [PATCH v2 1/6] spi: core: handle timeout error from transfer

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Date:   Wed, 4 Apr 2018 09:08:18 +0200
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Sergey Suloev <ssuloev@...altech.com>
Cc:     Mark Brown <broonie@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/6] spi: core: handle timeout error from
 transfer_one()

On Tue, Apr 03, 2018 at 07:24:11PM +0300, Sergey Suloev wrote:
> On 04/03/2018 07:18 PM, Mark Brown wrote:
> > On Tue, Apr 03, 2018 at 07:00:55PM +0300, Sergey Suloev wrote:
> > > On 04/03/2018 06:52 PM, Mark Brown wrote:
> > > > On Tue, Apr 03, 2018 at 06:29:00PM +0300, Sergey Suloev wrote:
> > > > > As long as sun4i/sun6i SPI drivers have overriden the default
> > > > > "wait for completion" procedure then we need to properly
> > > > > handle -ETIMEDOUT error from transfer_one().
> > > > Why is this connected to those drivers specifically?
> > > These 2 drivers have their own "waiting" code and not using the code from
> > > SPI core.
> > Does this not apply to any other driver - why is this something we only
> > have to do when these drivers do it?  That's what's setting off alarm
> > bells.
> 
> sun4i/sun6i drivers have let's say "smart" waiting while SPI core uses a
> fixed interval to wait.
> 
> I can't say for every SPI driver in kernel, that's outside of my area of
> expertise.

I'm not sure what's specific about the sun4i / sun6i case here. Your
patch doesn't have anything to do with the delay before the timeout,
but the fact that we return -ETIMEDOUT in the first place.

And I'm pretty sure that papering over an error returned by a driver
is not the right thing to do.

Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

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