linux-kernel - Re: [PATCH 00/11] ARM: at91: remove !DT support for at91rm9200

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Message-ID: <2241590.9KpWgUxqh8@wuerfel>
Date:	Fri, 28 Nov 2014 00:41:55 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	linux-kernel@...r.kernel.org,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
Subject: Re: [PATCH 00/11] ARM: at91: remove !DT support for at91rm9200

On Friday 28 November 2014 00:39:38 Boris Brezillon wrote:
> Hi Arnd,
> 
> On Fri, 28 Nov 2014 00:12:25 +0100
> Arnd Bergmann <arnd@...db.de> wrote:
> 
> > On Thursday 27 November 2014 18:12:43 Alexandre Belloni wrote:
> > > 
> > > As discussed some weeks ago, I prepared patches to switch sama5d[3-4] to
> > > multiplatform. We are still missing the SMC and matrix drivers to switch
> > > sam9 and rm9200.
> > 
> > I just looked at the drivers because I got curious, and to see if
> > there are still any low-hanging fruit, but I guess you already picked
> > them all 
> > 
> > > The currently affected drivers are:
> > >  - drivers/ata/pata_at91.c (SMC)
> > >  - drivers/pcmcia/at91_cf.c (SMC)
> > 
> > I guess the SMC should live in drivers/memory with an interface
> > similar to mvebu-devbus.c?
> 
> Actually, there's some work in progress to support the EBI/SMC blocks
> as a memory controller driver ;-):
> 
> http://thread.gmane.org/gmane.linux.kernel/1822096
> 
> I'll post a new version soon.

Ok, cool.

> > 
> > Seems doable but nontrivial.
> > 
> > >  - drivers/usb/gadget/udc/at91_udc.c (Matrix, this is the only one
> > >    for sam9)
> > 
> > Is at91_matrix a pin controller? With the board files removed, the udc
> > driver has the only two remaining calls to at91_matrix_{read,write}
> > for setting the pullup, so that could be modeled as a trivial pinctrl
> > driver
> 
> The matrix block is containing several system configuration registers.
> Most of them are related to AHB/APB bus config (master <-> slave
> priority, burst and some other configs I don't remember).
> Another register is here to define which HW logic is attached to an
> external device connected through the EBI (External Bus Interface):
> NAND, SDRAM, CompactFlash, ...
> And, as you pointed out, there's a register to configure the pullup of
> the UDC device.
> 
> As you can see, the matrix registers might be accessed by different
> drivers (include the EBI/SMC driver), hence I proposed to expose them as
> a syscon device (see the EBI/SMC series).
> 

Sounds good.

	Arnd
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