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From: Mark Brown <broonie@kernel.org>
To: Michal Simek <michal.simek@xilinx.com>
Cc: linux-kernel@vger.kernel.org, monstr@monstr.eu,
	"Sören Brinkmann" <soren.brinkmann@xilinx.com>,
	linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] spi: xilinx: Use standard num-cs binding
Date: Tue, 31 Mar 2015 06:47:14 +0100	[thread overview]
Message-ID: <20150331054714.GA2869@sirena.org.uk> (raw)
In-Reply-To: <1bd88fda-314c-496a-ba8b-e9292f9c411b@BY2FFO11FD023.protection.gbl>

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On Mon, Mar 30, 2015 at 08:46:10AM +0200, Michal Simek wrote:
> On 03/27/2015 06:53 PM, Mark Brown wrote:
> > On Fri, Mar 27, 2015 at 11:55:49AM +0100, Michal Simek wrote:

> > Please fix your mail client to word wrap within paragraphs at less than
> > 80 columns - this makes your mails easier to read and reply to.

> You are the first one who had problem with this. But I have setup lower
> limit and hopefully it is better now.

That looks better, yes...  I may just be the first one who's bothered
remarking on this.

> >> On 03/08/2015 08:00 PM, Mark Brown wrote:
> >>> On Fri, Jan 16, 2015 at 01:55:14PM +0100, Michal Simek wrote:

> > Remember that we can at least in theory have additional chip selects
> > that aren't controlled by the IP block but are instead GPIOs.  

> I agree with you but this can be generic case for every SPI driver. Also
> using external decoder is possible for every driver. Maybe there are
> others options via I2C too.

Remember that this in the context of me saying I don't think num-cs is
a particularly good idea at all...

> > There's
> > also some potential confusion for users between the number of chip
> > selects in use in a given system and the size of the bitfield that the
> > driver needs to take care of.

> num-ss-bits is autogenerated directly from design tools for particular
> hardware design and this size is exactly setup and hardcoded. (num-cs
> can be just the same case)
> If there are 5 bits there are 5 wires from IP. And value of num-ss-bits
> and num-cs will be the same.

But what your patch did was *replace* num-ss-bits in the binding, not
just add it.

> If user wants to use less lines then physically available we could
> potentially extend binding to say. num-ss-bit - number of chip selects
> available in hardware. num-cs - number of chip selects used by the driver.
> But I expect that this will be rejected because it is software setting
> not hardware description.

num-cs *is* a software setting.

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  reply	other threads:[~2015-03-31  5:47 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-16 12:55 Michal Simek
2015-02-12  9:45 ` Michal Simek
     [not found] ` <CAHTX3dJRGhwo7FW+VJxfEJmx-9FdjFN5EnxG0RRDfMOm3=VU4A@mail.gmail.com>
2015-02-14  5:35   ` Mark Brown
2015-02-23 10:22     ` Michal Simek
2015-02-24 14:52       ` Mark Brown
2015-03-08 19:00 ` Mark Brown
2015-03-27 10:55   ` Michal Simek
2015-03-27 17:53     ` Mark Brown
2015-03-30  6:46       ` Michal Simek
2015-03-31  5:47         ` Mark Brown [this message]
2015-03-31  8:16           ` Michal Simek
2015-03-31 11:16             ` Mark Brown
2015-03-31 11:25               ` Michal Simek
2015-03-31 12:24                 ` Mark Brown

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