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Date:   Mon, 5 Mar 2018 20:35:33 +0000
From:   Mark Brown <broonie@kernel.org>
To:     Sasha Levin <Alexander.Levin@microsoft.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Jonas Gorski <jonas.gorski@gmail.com>
Subject: Re: [PATCH AUTOSEL for 4.9 002/219] spi/bcm63xx: make spi subsystem
 aware of message size limits
Message-ID: <20180305203533.GP8588@sirena.org.uk>
References: <20180303222716.26640-1-alexander.levin@microsoft.com>
 <20180303222716.26640-2-alexander.levin@microsoft.com>
 <20180305102310.GC8588@sirena.org.uk>
 <20180305200744.afw64js6wnmyfqrb@sasha-lappy>
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On Mon, Mar 05, 2018 at 08:07:46PM +0000, Sasha Levin wrote:
> On Mon, Mar 05, 2018 at 10:23:10AM +0000, Mark Brown wrote:
> >On Sat, Mar 03, 2018 at 10:27:56PM +0000, Sasha Levin wrote:

> >> The bcm63xx SPI controller does not allow manual control of the CS
> >> lines and will toggle it automatically before and after sending data,
> >> so we are limited to messages that fit in the FIFO buffer. Since the CS
> >> lines aren't available as GPIOs either, we will need to make slave
> >> drivers aware of this limitation so they can handle them accordingly.

> >This seems really aggressive for stable...

> Why so?

It's exposing more capability information but it's in the "how did this
ever work without the fix" range, and I'd worry that this might cause us
to do something like start exercising handling code in client drivers
that had never been tested.  Not that I can immediately see any client
drivers in mainline that actually pay attention...  :/

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