From: mporter@ti.com (Matt Porter)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH 08/13] mmc: omap_hsmmc: limit max_segs with the EDMA DMAC
Date: Fri, 21 Sep 2012 15:03:12 -0400 [thread overview]
Message-ID: <20120921190312.GL16522@beef> (raw)
In-Reply-To: <20120921184721.GD31374@n2100.arm.linux.org.uk>
On Fri, Sep 21, 2012 at 07:47:21PM +0100, Russell King wrote:
> On Fri, Sep 21, 2012 at 10:45:29PM +0530, S, Venkatraman wrote:
> > On Thu, Sep 20, 2012 at 8:13 PM, Matt Porter <mporter@ti.com> wrote:
> > > The EDMA DMAC has a hardware limitation that prevents supporting
> > > scatter gather lists with any number of segments. Since the EDMA
> > > DMA Engine driver sets the maximum segments to 16, we do the
> > > same.
> > >
> > > Note: this can be removed once the DMA Engine API supports an
> > > API to query the DMAC's segment limitations.
> > >
> >
> > I wouldn't want to bind the properties of EDMA to omap_hsmmc as this patch
> > suggests. Why don't we have a max_segs property, which when explicitly specified
> > in DT, will override the default ?
>
> Why not have a generic way that DMA engine can export these kinds of
> properties?
That's exactly what my note above is suggesting...
Something along the lines of:
struct slave_sg_caps
{
int max_segs; /* <0 is no limit */
}
struct slave_sg_cap *
dmaengine_get_slave_sg_caps(struct dma_chan *chan);
I'm sure there are or will be other characteristics worth providing to
slave drivers.
-Matt
next prev parent reply other threads:[~2012-09-21 19:03 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-20 14:43 [RFC PATCH 00/13] DMA Engine support for AM33xx Matt Porter
2012-09-20 14:43 ` [RFC PATCH 01/13] ARM: davinci: move private EDMA API to arm/common Matt Porter
2012-09-21 7:10 ` Hebbar, Gururaja
2012-09-21 18:24 ` Matt Porter
2012-09-21 9:29 ` Russell King - ARM Linux
2012-09-21 9:33 ` Hebbar, Gururaja
2012-09-21 9:42 ` Russell King - ARM Linux
2012-09-21 18:34 ` Matt Porter
2012-09-21 18:50 ` Russell King - ARM Linux
2012-09-24 2:44 ` Hebbar, Gururaja
2012-09-20 14:43 ` [RFC PATCH 02/13] ARM: edma: remove unused transfer controller handlers Matt Porter
2012-09-20 14:43 ` [RFC PATCH 03/13] ARM: edma: add DT and runtime PM support for AM335x Matt Porter
2012-09-21 8:53 ` Hebbar, Gururaja
2012-10-09 18:58 ` Matt Porter
2012-09-20 14:43 ` [RFC PATCH 04/13] dmaengine: edma: enable build " Matt Porter
2012-09-20 14:43 ` [RFC PATCH 05/13] dma: Add TI EDMA device tree binding Matt Porter
2012-09-21 8:45 ` Hebbar, Gururaja
2012-09-21 18:23 ` Matt Porter
2012-09-20 14:43 ` [RFC PATCH 06/13] ARM: omap: add hsmmc am33xx specific init Matt Porter
2012-09-20 14:43 ` [RFC PATCH 07/13] mmc: omap_hsmmc: dma_request_slave_channel() support for DT platforms Matt Porter
2012-09-20 22:16 ` Tony Lindgren
2012-09-20 14:43 ` [RFC PATCH 08/13] mmc: omap_hsmmc: limit max_segs with the EDMA DMAC Matt Porter
2012-09-21 17:15 ` S, Venkatraman
2012-09-21 17:17 ` S, Venkatraman
2012-09-21 17:18 ` Felipe Balbi
2012-09-21 17:33 ` S, Venkatraman
2012-09-21 18:54 ` Matt Porter
2012-09-21 18:42 ` Matt Porter
2012-09-21 18:47 ` Russell King - ARM Linux
2012-09-21 19:03 ` Matt Porter [this message]
2012-09-27 9:41 ` Vinod Koul
2012-10-01 16:39 ` Matt Porter
2012-10-02 12:03 ` Vinod Koul
2012-09-20 14:43 ` [RFC PATCH 09/13] mmc: omap_hsmmc: add generic DMA request support to the DT binding Matt Porter
2012-09-20 14:43 ` [RFC PATCH 10/13] spi: omap2-mcspi: dma_request_slave_channel() support for DT platforms Matt Porter
2012-09-20 22:09 ` Tony Lindgren
2012-09-21 8:16 ` Arnd Bergmann
2012-09-21 15:42 ` Tony Lindgren
2012-09-21 18:37 ` Matt Porter
2012-09-27 9:36 ` Vinod Koul
2012-10-01 16:37 ` Matt Porter
2012-09-20 14:43 ` [RFC PATCH 11/13] spi: omap2-mcspi: add generic DMA request support to the DT binding Matt Porter
2012-09-20 14:43 ` [RFC PATCH 12/13] ARM: dts: add am33xx EDMA support Matt Porter
2012-09-20 14:43 ` [RFC PATCH 13/13] Documentation: add schedule for removing private EDMA API Matt Porter
2012-09-20 15:58 ` Mark Brown
2012-09-20 16:05 ` Matt Porter
2012-09-21 8:27 ` [RFC PATCH 00/13] DMA Engine support for AM33xx Hebbar, Gururaja
2012-09-21 18:22 ` Matt Porter
2012-09-24 11:26 ` Hebbar, Gururaja
2012-09-24 12:05 ` Matt Porter
2012-09-26 8:26 ` Hebbar, Gururaja
2012-09-26 13:01 ` Matt Porter
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