From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Emmanuel Vadot <manu@bidouilliste.com>
Cc: mark.rutland@arm.com, devicetree@vger.kernel.org,
linux@armlinux.org.uk, linux-kernel@vger.kernel.org,
wens@csie.org, robh+dt@kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] ARM: dts: sunxi: Add num-cs for A20 spi nodes
Date: Fri, 25 Nov 2016 16:20:47 +0100 [thread overview]
Message-ID: <20161125152047.oadxi2xbgm4kdd7q@lukather> (raw)
In-Reply-To: <20161124210509.be743aae84c26c6c2e666c6e@bidouilliste.com>
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On Thu, Nov 24, 2016 at 09:05:09PM +0100, Emmanuel Vadot wrote:
> On Thu, 24 Nov 2016 20:55:17 +0100
> Maxime Ripard <maxime.ripard@free-electrons.com> wrote:
>
> > On Tue, Nov 22, 2016 at 06:06:16PM +0100, Emmanuel Vadot wrote:
> > > The spi0 controller on the A20 have up to 4 CS (Chip Select) while the
> > > others three only have 1.
> > > Add the num-cs property to each node.
> > >
> > > Signed-off-by: Emmanuel Vadot <manu@bidouilliste.com>
> >
> > I don't think we have any code that uses it at the moment. What is the
> > rationale behind this patch?
> >
> > Thanks!
> > Maxime
> >
> > --
> > Maxime Ripard, Free Electrons
> > Embedded Linux and Kernel engineering
> > http://free-electrons.com
>
> Hi Maxime,
>
> If num-cs isn't present nothing prevent to start a transfer with a
> non-valid CS pin, resulting in an error.
> num-cs are default property especially made for this and a SPI driver
> should try to get the property at probe/attach time.
Yes, but as far as I know, our driver doesn't. I'm all in for having
support for that in our driver, but without it, that patch is kind of
useless.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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next prev parent reply other threads:[~2016-11-25 15:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-22 17:06 [PATCH] ARM: dts: sunxi: Add num-cs for A20 spi nodes Emmanuel Vadot
2016-11-24 19:55 ` Maxime Ripard
2016-11-24 20:05 ` Emmanuel Vadot
2016-11-25 15:20 ` Maxime Ripard [this message]
2016-11-25 21:07 ` Emmanuel Vadot
2016-12-01 9:21 ` Maxime Ripard
2016-12-01 10:24 ` Emmanuel Vadot
2016-12-05 9:28 ` Maxime Ripard
2016-12-05 9:39 ` Emmanuel Vadot
[not found] ` <20161122170616.29557-1-manu-xXdDKFdH5B3kFDPD4ZthVA@public.gmane.org>
2016-12-03 23:10 ` kbuild test robot
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