linux-kernel - Re: [PATCH] spi: atmel: Fix crash when using more than 4 gpio CS

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Message-ID: <20190919172350.GZ21254@piout.net>
Date:   Thu, 19 Sep 2019 19:23:50 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Gregory CLEMENT <gregory.clement@...tlin.com>,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        linux-arm-kernel@...ts.infradead.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH] spi: atmel: Fix crash when using more than 4 gpio CS

On 19/09/2019 17:03:15+0100, Mark Brown wrote:
> On Thu, Sep 19, 2019 at 05:38:47PM +0200, Gregory CLEMENT wrote:
> 
> > With this patch, when using a gpio CS, the hardware CS0 is always
> > used. Thanks to this, there is no more limitation for the number of
> > gpio CS we can use.
> 
> This is going to break any system where we use both a GPIO chip select
> and chip select 0.  Ideally we'd try to figure out an unused chip select
> to use here...

The point is that this use case is already broken and this patch fixes
the crash and is easily backportable.

Fixing the CS + gpio CS should probably be done in a separate patch.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com