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Date: Mon, 17 Sep 2012 09:36:54 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Vinod Koul <vinod.koul@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, Dan Williams <djbw@fb.com>,
        Arnd Bergmann <arnd@arndb.de>, linus.walleij@linaro.org,
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        Sascha Hauer <kernel@pengutronix.de>,
        Kukjin Kim <kgene.kim@samsung.com>,
        viresh kumar <viresh.kumar@linaro.org>,
        Paul Mundt <lethal@linux-sh.org>
Subject: Re: [PATCH] dmaengine: add dmanegine slave map api's
Message-ID: <20120917083654.GO12245@n2100.arm.linux.org.uk>
References: <1347615189-27052-1-git-send-email-vinod.koul@linux.intel.com> <20120914094155.GC12245@n2100.arm.linux.org.uk> <1347619868.1943.113.camel@vkoul-udesk3> <20120914111842.GD12245@n2100.arm.linux.org.uk> <1347853223.1943.136.camel@vkoul-udesk3>
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On Mon, Sep 17, 2012 at 09:10:23AM +0530, Vinod Koul wrote:
> On Fri, 2012-09-14 at 12:18 +0100, Russell King - ARM Linux wrote:
> > I'm not saying take the slave_id out of the map.  I'm saying, let the
> > DMA engine driver itself figure out what dma_chan to return. 
> But wont that assume the dma controller knows which channel to allocate.
> And how would it know this information? This can be problematic for hard
> wired muxes, but can be easily done for controller which have
> programmable mux.

Well, as I have already said, at the moment you're returning the _first_
_free_ _channel_ on a DMA device, which almost certainly will always be
the wrong one.