linux-kernel - Re: [PATCH] spi-nor: Add support for Atmel Dataflash memories

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Message-ID: <d9b3fffd-dded-b210-e058-13a326b4fb8f@microchip.com>
Date:   Mon, 7 May 2018 10:23:56 +0200
From:   Nicolas Ferre <nicolas.ferre@...rochip.com>
To:     Boris Brezillon <boris.brezillon@...tlin.com>,
        Radu Pirea <radu.pirea@...rochip.com>
CC:     <cyrille.pitchen@...ev4u.fr>, <marek.vasut@...il.com>,
        <dwmw2@...radead.org>, <computersforpeace@...il.com>,
        <richard@....at>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Tudor Ambarus - M18064 <Tudor.Ambarus@...rochip.com>
Subject: Re: [PATCH] spi-nor: Add support for Atmel Dataflash memories

On 04/05/2018 at 20:38, Boris Brezillon wrote:
> Hi Radu,
> 
> Sorry for the late reply.
> 
> On Wed, 28 Feb 2018 13:55:01 +0200
> Radu Pirea <radu.pirea@...rochip.com> wrote:
> 
>> This patch add support in spi-nor for allmost all dataflash memories
>> supported by old mtd_dataflash driver.
> 
> Those devices clearly use a different instruction set, so I don't think
> they fit in this framework. Can you tell us why you want to move
> dataflash support to the SPI NOR framework. I think I know why, but I'd
> like to get your version. My guess is that some people want to connect
> dataflash chips to the Atmel QSPI controller, and it's not supported
> right now because the Atmel QSPI controller implements the SPI-NOR
> interface and not the generic SPI one, thus preventing anything that
> is not a SPI NOR from being connected to this controller.
> 
> If I'm right, then the solution is to convert the QSPI driver to the
> spi-mem interface [1] and move it to drivers/spi/.

No, I we didn't think about this. Dataflash is not so popular those days 
and we don't want to revive it anyway. Our QSPI driver has already a lot 
of things to handle in QSPI-related topics to not mix it with oldies ;-)

The rationale behind this work is to get rid of the very old dataflash 
standalone driver and benefit from the whole spi-nor infrastructure like 
cache coherency management and DMA handling (which were broken in the 
old dataflash driver in recent kernels).

Best regards,
   Nicolas


> [1]http://patchwork.ozlabs.org/project/linux-mtd/list/?series=41174
> 


-- 
Nicolas Ferre