From mboxrd@z Thu Jan 1 00:00:00 1970 From: zonque@gmail.com (Daniel Mack) Date: Thu, 04 Oct 2012 11:21:46 +0200 Subject: [alsa-devel] [PATCH 2/3] ASoC: Davinci: pcm: add support for sram-support-less platforms In-Reply-To: <506B1B46.2070006@gmail.com> References: <1346417459-30042-1-git-send-email-gururaja.hebbar@ti.com> <1346417459-30042-3-git-send-email-gururaja.hebbar@ti.com> <20120922153313.GN4495@opensource.wolfsonmicro.com> <506A9C65.5040309@ti.com> <20121002093753.GU4360@opensource.wolfsonmicro.com> <506AC303.9080906@gmail.com> <506ACACE.4030308@ti.com> <506AEF57.2000306@gmail.com> <20121002164116.GT5641@beef> <506B1B46.2070006@gmail.com> Message-ID: <506D552A.2000506@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02.10.2012 18:50, Daniel Mack wrote: > On 02.10.2012 18:41, Matt Porter wrote: >> On Tue, Oct 02, 2012 at 03:42:47PM +0200, Daniel Mack wrote: >>> On 02.10.2012 13:06, Sekhar Nori wrote: >>>> On 10/2/2012 4:03 PM, Daniel Mack wrote: >>>>> On 02.10.2012 11:37, Mark Brown wrote: >>>>>> On Tue, Oct 02, 2012 at 10:48:53AM +0300, Peter Ujfalusi wrote: >>>>>> >>>>>>> I also agree that ifdef is not a good solution. >>>>>>> It is better to have this information passed as device_data and via DT it can >>>>>>> be decided based on the compatible property for the device. >>>>>> >>>>>> That's not really the problem here - the problem is that the APIs used >>>>>> to get the SRAM are DaVinci only so it's not possible to build on OMAP >>>>>> or other platforms. The SRAM code needs to move to a standard API. >>>>> >>>>> What about following Matt Porter's idea and ignore the SRAM code >>>>> entirely and port the entire PCM code to generic dmaengine code first? >>>>> The EDMA driver needs to learn support for cyclic DMA for that, and I >>>>> might give that a try in near future. >>>>> >>>>> Later on, the SRAM ping-pong code can get added back using genalloc >>>>> functions, as Sekhar proposed. That needs to be done by someone who has >>>>> access to a Davinci board though, I only have a AM33xx/OMAP here. >>>> >>>> We cannot "get rid" of SRAM code and add it back "later". It is required >>>> for most DaVinci parts. The SRAM code can be converted to use genalloc >>>> (conversion should be straightforward and I can help test it) and the >>>> code that uses SRAM can probably keep using the private EDMA API till >>>> the dmaengine EDMA driver has cyclic DMA support. Matt has already >>>> posted patches to move private EDMA APIs to a common location. That >>>> should keep AM335x build from breaking. Is this something that is feasible? >>> >>> Yes - by "later" I just meant in a subsequent patch. But you're probably >>> right, we can also do that first. >>> >>> I'm looking at that right now and the problem seems that we don't have a >>> sane way to dynamically look up gen_pools independently of the actual >>> run-time platform. All users of gen_pools seem to know which platform >>> they run on and access a platform-specific pool. So I don't currently >>> see how we could implement multi-platform code, gen_pools are fine but >>> don't solve the problem here. >>> >>> Would it be an idea to add a char* member to gen_pools and a function >>> that can be used to dynamically look it up again? If a buffer with a >>> certain name exists, we can use it and install that ping-pong buffer, >>> otherwise we just don't. While that would be easy to do, it's a >>> tree-wide change. >>> >>> Is there a better way that I miss? >> >> At the high level there's two platform models we have to handle, the >> boot from board file !DT case, and then the boot from DT case. Since >> Davinci is just starting DT conversion, we mostly care about the !DT >> base in which the struct gen_pool * is passed in pdata to the ASoC >> driver. It is then selectable on a per-platform basis where the decision >> should be made. >> >> Given a separate discussion with Sekhar, we're only going to have one >> SRAM pool on any DaVinci part right now...this was only a question on >> L138 anyway. But regardless, the created gen_pool will be passed via >> pdata. > > I thought about this too, as mmp does it that way. > >> Since DT conversion is starting and we need to consider that now, >> the idea there is to use the DT-based generic sram driver [1] such that >> when we do boot from DT on Davinci, the genpool is provided via phandle >> and the pointer extracted with the OF helpers that are part of the >> series. > > A phandle is the cleanest way I think, yes. > >> That's pretty much it. I'm reworking the backend support as discussed >> with Sekhar wrt to my uio_pruss series. I can post a standalone series >> that just replaces sram_* with genalloc for davinci ASoC. > > As you can also test it, it would be easiest if you came up with a patch > for that, yes. I can have a look at the dma bits laters, once my OMAP > board finally works with the code as it currently stands. I'm still > fighting with the mcasp driver right now ... I quickly prepared two patches to change that, so that topic is out of the way. But I did only compile-test them on OMAP - could you check on your Davinci platform? Note that these apply on top of the patch in discussion here (which isn't applied to the asoc tree yet). Daniel -------------- next part -------------- A non-text attachment was scrubbed... Name: 0001-ARM-davinci-pass-SRAM-gen_pool-to-mcasp-platform-dat.patch Type: text/x-patch Size: 8048 bytes Desc: not available URL: -------------- next part -------------- A non-text attachment was scrubbed... Name: 0002-ALSA-ASoC-McASP-use-gen_pool-from-platform-data.patch Type: text/x-patch Size: 4201 bytes Desc: not available URL: