Re: [PATCH v5] spi: spi-ti-qspi: Add DMA support for QSPI mmap read

Path	csiph.com!aioe.org!gothmog.csi.it!bofh.it!news.nic.it!robomod
From	Mark Brown <broonie@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v5] spi: spi-ti-qspi: Add DMA support for QSPI mmap read
Date	Tue, 16 Aug 2016 20:50:01 +0200
Message-ID	<s6RAZ-6EN-3@gated-at.bofh.it> (permalink)
References	<s4d4Z-6KH-7@gated-at.bofh.it> <s4dy2-6VH-37@gated-at.bofh.it> <s4eNr-7FJ-9@gated-at.bofh.it>
MIME-Version	1.0
Content-Type	multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="bS87dHSPlkoPpvQ6"
Content-Disposition	inline
X-Cookie	I can't drive 55.
User-Agent	Mutt/1.6.0 (2016-04-01)
X-Sa-Exim-Connect-IP	2a01:348:6:8808:fab::3
X-Sa-Exim-Mail-From	broonie@sirena.org.uk
X-Sa-Exim-Version	4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000)
X-Sa-Exim-Scanned	No (on mezzanine.sirena.org.uk); Unknown failure
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	40
Organization	linux.* mail to news gateway
X-Original-Cc	linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org
X-Original-Date	Tue, 16 Aug 2016 19:42:53 +0100
X-Original-Message-ID	<20160816184253.GC9347@sirena.org.uk>
X-Original-References	<20160809110311.13521-1-vigneshr@ti.com> <20160809113329.GA9347@sirena.org.uk> <13e676c2-7e2f-d1c5-5312-bc2e11a6b6a1@ti.com>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1464011

Show key headers only | View raw

[Multipart message — attachments visible in raw view] - view raw

On Tue, Aug 09, 2016 at 06:20:01PM +0530, Vignesh R wrote:
> 
> 

> According to this thread[1], converting virtual address
> pointer into scatterlist which is then DMA mapped is unsafe on systems
> with certain cache architecture. Hence, I added code to handle kmap
> buffers inside the driver rather than updating generic spi-core code.

That's saying that things that aren't covered aren't DMAable safely at
all which is a more general issue...

> If its okay to update the spi_map_buf() to handle kmap buffers as above
> then I can submit the patch accordingly.

Yes, the whole point is that this is all in generic code so drivers
don't need to worry about it.

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH v5] spi: spi-ti-qspi: Add DMA support for QSPI mmap read Mark Brown <broonie@kernel.org> - 2016-08-16 20:50 +0200
  Re: [PATCH v5] spi: spi-ti-qspi: Add DMA support for QSPI mmap read Vignesh R <vigneshr@ti.com> - 2016-08-17 07:20 +0200

csiph-web