From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mail.bootlin.com ([62.4.15.54])
 by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux))
 id 1g2C9G-0006Ar-Te
 for linux-mtd@lists.infradead.org; Tue, 18 Sep 2018 09:18:24 +0000
Date: Tue, 18 Sep 2018 11:18:07 +0200
From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>, Brian Norris
 <computersforpeace@gmail.com>, Marek Vasut <marek.vasut@gmail.com>, Richard
 Weinberger <richard@nod.at>, linux-mtd@lists.infradead.org,
 stable@vger.kernel.org
Subject: Re: [PATCH v2] mtd: devices: m25p80: Make sure the buffer passed in
 op is DMA-able
Message-ID: <20180918111807.2ee5ccb8@bbrezillon>
In-Reply-To: <8e5e8113-b091-6d3e-50d4-3e70e9372016@linux.intel.com>
References: <20180917143130.23007-1-boris.brezillon@bootlin.com>
 <8e5e8113-b091-6d3e-50d4-3e70e9372016@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
List-Id: Linux MTD discussion mailing list <linux-mtd.lists.infradead.org>
List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-mtd>,
 <mailto:linux-mtd-request@lists.infradead.org?subject=unsubscribe>
List-Archive: <http://lists.infradead.org/pipermail/linux-mtd/>
List-Post: <mailto:linux-mtd@lists.infradead.org>
List-Help: <mailto:linux-mtd-request@lists.infradead.org?subject=help>
List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-mtd>,
 <mailto:linux-mtd-request@lists.infradead.org?subject=subscribe>

On Tue, 18 Sep 2018 10:59:17 +0300
Jarkko Nikula <jarkko.nikula@linux.intel.com> wrote:

> On 09/17/2018 05:31 PM, Boris Brezillon wrote:
> > As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be
> > DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx()
> > API") failed to follow this rule as buffers passed to  
> > ->{read,write}_reg() are usually placed on the stack.  
> > 
> > Fix that by allocating a scratch buffer and copying the data around.
> > 
> > Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API")
> > Reported-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> > ---
> > Note that the ->{read,write}() path is still buggy since nothing
> > guarantees that buffers passed by the MTD layer to the SPI NOR layer
> > are DMA-able, but this is a long-standing issue which we'll have to
> > address at the spi-nor level (this layer can choose the bounce buffer
> > size based on nor->page_size).
> > 
> > Changes in v2:
> > - Copy the data from scratchbuf in the ->read_reg() path
> > ---
> >   drivers/mtd/devices/m25p80.c | 26 +++++++++++++++++++++++---
> >   1 file changed, 23 insertions(+), 3 deletions(-)
> >   
> Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> Reviewed-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Queued to mtd/master. Thanks for testing and reviewing the patch.

Regards,

Boris