linux-kernel - Re: [PATCH 1/3] mtd: spi-nor: Add Octal mode support for mt35xu512aba

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Message-ID: <20181004093925.2961d881@bbrezillon>
Date:   Thu, 4 Oct 2018 09:39:25 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Yogesh Narayan Gaur <yogeshnarayan.gaur@....com>
Cc:     Vignesh R <vigneshr@...com>, Marek Vasut <marek.vasut@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Brian Norris <computersforpeace@...il.com>,
        Linux ARM Mailing List <linux-arm-kernel@...ts.infradead.org>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "juliensu@...c.com.tw" <juliensu@...c.com.tw>,
        "zhengxunli@...c.com.tw" <zhengxunli@...c.com.tw>,
        "masonccyang@...c.com.tw" <masonccyang@...c.com.tw>
Subject: Re: [PATCH 1/3] mtd: spi-nor: Add Octal mode support for
 mt35xu512aba

+Julien, Zhengxunli and Mason from Macronix

Hi Yogesh,

On Thu, 4 Oct 2018 06:51:41 +0000
Yogesh Narayan Gaur <yogeshnarayan.gaur@....com> wrote:

> Hi Vignesh,
> 
> > -----Original Message-----
> > From: Vignesh R [mailto:vigneshr@...com]
> > Sent: Wednesday, October 3, 2018 10:26 PM
> > To: Boris Brezillon <boris.brezillon@...tlin.com>; Marek Vasut
> > <marek.vasut@...il.com>; Rob Herring <robh+dt@...nel.org>
> > Cc: Brian Norris <computersforpeace@...il.com>; Yogesh Narayan Gaur
> > <yogeshnarayan.gaur@....com>; Linux ARM Mailing List <linux-arm-  
> > kernel@...ts.infradead.org>; linux-mtd@...ts.infradead.org;  
> > devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; Vignesh R
> > <vigneshr@...com>
> > Subject: [PATCH 1/3] mtd: spi-nor: Add Octal mode support for mt35xu512aba
> > 
> > Micron's mt35xu512aba flash is an Octal flash that has x8 IO lines. It supports
> > read/write over 8 IO lines simulatenously. Add support for Octal read mode for
> > Micron mt35xu512aba.
> > Unfortunately, this flash is only complaint to SFDP JESD216B and does not seem
> > to support newer JESD216C standard that provides auto detection of Octal
> > mode capabilities and opcodes. Therefore, this capability is manually added
> > using new SPI_NOR_OCTAL_READ flag.
> >   
> 
> Thanks for sending the patch-set of adding octal support.
> If possible, can you share the MT35x datasheet?
> 
> I also have the patch ready in which I have added support for Read (1-1-8 and 1-8-8) protocol and Write (1-1-8 and 1-8-8).
> Also have added support of Octal in driver/spi/spi.c framework.
> 
> IMO, we would collaborate our patches.

Looks like we are of stepping on each others toes here (see this branch
[1]). I guess it's not a problem if we agree on who is working on what.

Yogesh, you already sent "spi: add flags for octal I/O data
transfer" [3] which is only adding the new OCTAL flags but is not
patching spi.c and spi-mem.c to take those new flags into account. Here
is my version of this patch [2] (it's still missing an update of
SPI_MEM_MAX_BUSWIDTH). Let me know what you want to do (rework your
version to address the problem or take mine).

Regarding other patches in [2], they're mainly here to add support for
X-X-X and DTR modes and get the m25p80 logic integrated in spi-nor.c so
that we can really check which NOR operations are supported by the SPI
controller.

Regards,

Boris

[1]https://github.com/bbrezillon/linux/commits/spi-nor/octo
[2]https://github.com/bbrezillon/linux/commit/9854a8fdd23f64e79859fd07a71d4a1c57b812f2
[3]https://patchwork.ozlabs.org/patch/894916/