linux-kernel - Re: [PATCH v2 2/2] clk: at91: add Flexcom clock

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Message-ID: <20150602171536.GG1715@piout.net>
Date:	Tue, 2 Jun 2015 19:15:36 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:	Cyrille Pitchen <cyrille.pitchen@...el.com>,
	nicolas.ferre@...el.com, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] clk: at91: add Flexcom clock

On 02/06/2015 at 19:04:35 +0200, Boris Brezillon wrote :
> Hi Cyrille,
> 
> On Tue, 2 Jun 2015 18:57:19 +0200
> Cyrille Pitchen <cyrille.pitchen@...el.com> wrote:
> 
> > This driver supports the new Atmel Flexcom. The Flexcom is a wrapper which
> > integrates one SPI controller, one I2C controller and one USART. Only one
> > function can be enabled at a time. This driver selects the function once for
> > all, when the Flexcom is probed, according to the value of the new
> > "atmel,flexcom-mode" device tree property.
> > 
> > This driver has chosen to present the Flexcom to the system as a clock so the
> > implementation is seamless for the existing Atmel SPI, I2C and USART drivers.
> 
> Could detail a bit more why you chose to represent this flexcom IP as
> a clock device ?
> 
> I don't like to use this 'DT should represent real hardware' argument,
> but to me, it looks like you're trying to use a false hardware
> representation to avoid changing the peripheral drivers code, which is
> wrong since the DT is supposed to represent the hardware blocks.
> 
> How about representing the flexcom as an MFD instead ?
> 

It should probably be represented as an MFD. The MFD driver will parse
the chosen configuration and the probe the correct driver. You can have
a look at the recent ST LPC driver from Lee.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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