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From: Emmanuel Vadot <manu@bidouilliste.com>
To: Maxime Ripard <maxime.ripard@free-electrons.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: Thu, 24 Nov 2016 21:05:09 +0100	[thread overview]
Message-ID: <20161124210509.be743aae84c26c6c2e666c6e@bidouilliste.com> (raw)
In-Reply-To: <20161124195517.qrq7briu3pwjnp4n@lukather>

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.

 Cheers,

-- 
Emmanuel Vadot <manu@bidouilliste.com> <manu@freebsd.org>

WARNING: multiple messages have this Message-ID (diff)
From: manu@bidouilliste.com (Emmanuel Vadot)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: dts: sunxi: Add num-cs for A20 spi nodes
Date: Thu, 24 Nov 2016 21:05:09 +0100	[thread overview]
Message-ID: <20161124210509.be743aae84c26c6c2e666c6e@bidouilliste.com> (raw)
In-Reply-To: <20161124195517.qrq7briu3pwjnp4n@lukather>

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.

 Cheers,

-- 
Emmanuel Vadot <manu@bidouilliste.com> <manu@freebsd.org>

  reply	other threads:[~2016-11-24 20:05 UTC|newest]

Thread overview: 26+ 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
2016-11-22 17:06 ` Emmanuel Vadot
2016-11-22 17:06 ` Emmanuel Vadot
2016-11-24 19:55 ` Maxime Ripard
2016-11-24 19:55   ` Maxime Ripard
2016-11-24 19:55   ` Maxime Ripard
2016-11-24 20:05   ` Emmanuel Vadot [this message]
2016-11-24 20:05     ` Emmanuel Vadot
2016-11-25 15:20     ` Maxime Ripard
2016-11-25 15:20       ` Maxime Ripard
2016-11-25 15:20       ` Maxime Ripard
2016-11-25 21:07       ` Emmanuel Vadot
2016-11-25 21:07         ` Emmanuel Vadot
2016-11-25 21:07         ` Emmanuel Vadot
2016-12-01  9:21         ` Maxime Ripard
2016-12-01  9:21           ` Maxime Ripard
2016-12-01 10:24           ` Emmanuel Vadot
2016-12-01 10:24             ` Emmanuel Vadot
2016-12-01 10:24             ` Emmanuel Vadot
2016-12-05  9:28             ` Maxime Ripard
2016-12-05  9:28               ` Maxime Ripard
2016-12-05  9:39               ` Emmanuel Vadot
2016-12-05  9:39                 ` Emmanuel Vadot
2016-12-03 23:10 ` kbuild test robot
2016-12-03 23:10   ` kbuild test robot
2016-12-03 23:10   ` kbuild test robot

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