linux-kernel - Re: [PATCH 0/3] mtd: spi-nor: fix DMA-unsafe buffer issue between MTD and SPI

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Message-ID: <46499c32-f513-1781-bb42-f56b1f534941@ti.com>
Date:   Fri, 29 Dec 2017 14:46:31 +0530
From:   Vignesh R <vigneshr@...com>
To:     Trent Piepho <tpiepho@...inj.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "cyrille.pitchen@...ev4u.fr" <cyrille.pitchen@...ev4u.fr>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "computersforpeace@...il.com" <computersforpeace@...il.com>,
        "boris.brezillon@...e-electrons.com" 
        <boris.brezillon@...e-electrons.com>,
        "richard@....at" <richard@....at>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>
CC:     "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "nicolas.ferre@...rochip.com" <nicolas.ferre@...rochip.com>,
        "robh@...nel.org" <robh@...nel.org>,
        "radu.pirea@...rochip.com" <radu.pirea@...rochip.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 0/3] mtd: spi-nor: fix DMA-unsafe buffer issue between MTD
 and SPI



On Wednesday 27 December 2017 12:15 AM, Trent Piepho wrote:
> On Sun, 2017-12-24 at 05:36 +0100, Cyrille Pitchen wrote:
>> this series tries to solve a long time issue of compatibility between the
>> MTD and SPI sub-systems about whether we should use DMA-safe memory.
> 
> Can this should replace SoC specific fixes like:
> 
> c687c46e9e45
> spi: spi-ti-qspi: Use bounce buffer if read buffer is not DMA'ble
> 

Yes, I plan to revert this patch once m25p80 starts using bounce buffers.

I am interested in knowing which other SPI clients end up passing non
DMA'able buffers. AFAIK, its UBIFS and JFFS2. Most other SPI devices on
TI boards that I have dealt with like Touch, Sensors (IIO), GPIO
expanders etc all provide DMA'able buffers.


-- 
Regards
Vignesh