From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Porter Subject: Re: [PATCH v6 03/10] ARM: edma: add AM33XX support to the private EDMA API Date: Fri, 1 Feb 2013 06:57:39 -0500 Message-ID: <20130201115738.GL2244@beef> References: <1359529229-22207-1-git-send-email-mporter@ti.com> <201301300932.58732.arnd@arndb.de> <20130131183255.GI2244@beef> <6932828d68394f71ba6df8e6bf608635@DFLE72.ent.ti.com> <20130131214241.GJ2244@beef> <1359698501.14894.74.camel@cumari.coelho.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linux DaVinci Kernel List , Chris Ball , Russell King , "Cousson, Benoit" , Arnd Bergmann , Linux Documentation List , Tony Lindgren , Devicetree Discuss , Mark Brown , Linux MMC List , Linux Kernel Mailing List , Rob Herring , Grant Likely , Vinod Koul , Rob Landley , Dan Williams , Padma Venkat , Linux SPI Devel List , Linux OMAP List , Linux ARM Kernel List Return-path: Content-Disposition: inline In-Reply-To: <1359698501.14894.74.camel@cumari.coelho.fi> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org On Fri, Feb 01, 2013 at 08:01:41AM +0200, Luciano Coelho wrote: > On Thu, 2013-01-31 at 16:42 -0500, Matt Porter wrote: > > On Thu, Jan 31, 2013 at 08:58:39PM +0000, Arnd Bergmann wrote: > > > On Thursday 31 January 2013, Matt Porter wrote: > > > > On Wed, Jan 30, 2013 at 09:32:58AM +0000, Arnd Bergmann wrote: > > > > > On Wednesday 30 January 2013, Matt Porter wrote: > > > > > > + dma_cap_set(DMA_SLAVE, edma_filter_info.dma_cap); > > > > > > + of_dma_controller_register(dev->of_node, > > > > > > + of_dma_simple_xlate, > > > > > > + &edma_filter_info); > > > > > > + } > > > > > > > > > > How do you actually deal with the problem mentioned by Padma, that > > > > > the filter function does not know which edma instance it is looking > > > > > at? If you assume that there can only be a single edma instance in > > > > > the system, that is probably a limitation that should be documented > > > > > somewhere, and ideally the probe() function should check for that. > > > > > > > > I make an assumption of one edma instance in the system in the case of > > > > DT being populated. This is always true right now as the only SoC with > > > > two EDMA controllers in existence is Davinci DA850. Until recently, > > > > Davinci had no DT support. Given the steady work being done today on DT > > > > support for DA850, it'll probably be something needed in 3.10. > > > > > > > > I will add a comment and check in probe() to capture this assumption > > > > and then plan to update separately to support DA850 booting from DT. > > > > > > Ok, sounds good. Hopefully by then we will already have a nicer > > > way to write an xlate function that does not rely on a filter > > > function. > > > > Yes, it would be nice to avoid what Padma had to do. I should have > > mentioned also that the second EDMA on DA850 has no DMA events of > > immediate use on it anyway. All the in-kernel users use events on the > > first controller, except for the second MMC instance. That's only used > > for a wl12xx module on the EVM and that driver has no DT support so it > > doesn't matter yet in the DT case. Because of this, DA850 can actually > > add EDMA DT support immediately (on top of this series) and add DMA > > support to the DT support already posted for the Davinci SPI and MMC > > client drivers. > > I haven't followed this whole discussion in details, but please notice > that I'm aiming to get DT support for the WiLink modules (wlcore, > wl12xx...) for 3.10. ;) Great, looks like we'll all be synced then. ;) -Matt