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From: Matt Porter <mporter@ti.com>
To: Vinod Koul <vinod.koul@linux.intel.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
	"S, Venkatraman" <svenkatr@ti.com>,
	Linux DaVinci Kernel List 
	<davinci-linux-open-source@linux.davincidsp.com>,
	Linux OMAP List <linux-omap@vger.kernel.org>,
	Benoit Cousson <b-cousson@ti.com>, Arnd Bergmann <arnd@arndb.de>,
	Linux Documentation List <linux-doc@vger.kernel.org>,
	Tony Lindgren <tony@atomide.com>,
	Linux MMC List <linux-mmc@vger.kernel.org>,
	Devicetree Discuss <devicetree-discuss@lists.ozlabs.org>,
	Mark Brown <broonie@opensource.wolfsonmicro.com>,
	Sekhar Nori <nsekhar@ti.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Rob Herring <rob.herring@calxeda.com>,
	Grant Likely <grant.likely@secretlab.ca>,
	Rob Landley <rob@landley.net>, Dan Williams <djbw@fb.com>,
	Linux SPI Devel List  <spi-devel-general@lists.sourceforge.net>,
	Chris Ball <cjb@laptop.org>,
	Linux ARM Kernel List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH 08/13] mmc: omap_hsmmc: limit max_segs with the EDMA DMAC
Date: Mon, 1 Oct 2012 12:39:55 -0400	[thread overview]
Message-ID: <20121001163955.GO5641@beef> (raw)
In-Reply-To: <1348738868.1648.13.camel@vkoul-udesk3>

On Thu, Sep 27, 2012 at 03:11:08PM +0530, Vinod Koul wrote:
> On Fri, 2012-09-21 at 19:47 +0100, Russell King - ARM Linux 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?
> We discussed this at KS. I was of opinion that  DMA engine should export
> controller and channel capabilities as part of the channel it returns.
> 
> Some folks had an opinion that they already know how to use controller
> so may not be very helpful, but if it is going to help (which I think),
> i have a patch for this :)

Anything you can show at this point? ;) I'd be happy to drop the half-hack
for a real API. If not, I'm going to carry that to v2 atm.

-Matt

  reply	other threads:[~2012-10-01 16:39 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
2012-09-27  9:41       ` Vinod Koul
2012-10-01 16:39         ` Matt Porter [this message]
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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