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

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Message-ID: <20190920105101.GA3822@sirena.co.uk>
Date:   Fri, 20 Sep 2019 11:51:01 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
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 Thu, Sep 19, 2019 at 07:23:50PM +0200, Alexandre Belloni wrote:
> On 19/09/2019 17:03:15+0100, Mark Brown wrote:

> > 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.

If the GPIO is overlaid on any of the existing slots (except GPIO 0)
then it'll cause GPIO 0 to start toggling.  I'm not convinced that the
code doesn't currently support that.

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