Re: [PATCH v12 05/11] edma: config: Enable config options for EDMA

From: Arnd Bergmann <arnd@arndb.de>
To: Joel A Fernandes <agnel.joel@gmail.com>
Cc: Sekhar Nori <nsekhar@ti.com>, Joel A Fernandes <joelagnel@ti.com>,
	Tony Lindgren <tony@atomide.com>, Matt Porter <matt@ohporter.com>,
	Grant Likely <grant.likely@secretlab.ca>,
	Rob Herring <rob.herring@calxeda.com>,
	Vinod Koul <vinod.koul@intel.com>,
	Mark Brown <broonie@opensource.wolfsonmicro.com>,
	Benoit Cousson <b-cousson@ti.com>,
	Russell King <linux@arm.linux.org.uk>,
	Rob Landley <rob@landley.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jason Kridner <jkridner@beagleboard.org>,
	Koen Kooi <koen@beagleboard.org>,
	Devicetree Discuss <devicetree-discuss@lists.ozlabs.org>,
	Linux OMAP List <linux-omap@vger.kernel.org>,
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Subject: Re: [PATCH v12 05/11] edma: config: Enable config options for EDMA
Date: Mon, 24 Jun 2013 23:07:35 +0200	[thread overview]
Message-ID: <201306242307.35840.arnd@arndb.de> (raw)
In-Reply-To: <CAD=GYpYwswOYGHRzZ6SeKD+sEfi-7s3HuqKr7G0OXQWFCA_EtQ@mail.gmail.com>

On Monday 24 June 2013, Joel A Fernandes wrote:
> >> Yes sure, right now they are defined  as follows in include/linux/edma.h:
> >>
> >> #if defined(CONFIG_TI_EDMA) || defined(CONFIG_TI_EDMA_MODULE)
> >> bool edma_filter_fn(struct dma_chan *, void *);
> >> #else
> >> static inline bool edma_filter_fn(struct dma_chan *chan, void *param)
> >> {
> >> return false;
> >> }
> >> #endif
> >
> > It's best to just define the filter function in the platform
> > code and pass a pointer to it through platform data. The way you do
> > it above makes the slave drivers inherently nonportable.
> 
> But with DT-only platforms, can you really do that?

The nice thing about this is that with a DT-only platform, the
filter function will automatically go away: you have no
platform_data, which means that if you are using
dma_request_slave_channel_compat, you just pass NULL as the
filter and the filter-data, same as just calling
dma_request_slave_channel.

	Arnd