Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754902Ab2JBQOF (ORCPT ); Tue, 2 Oct 2012 12:14:05 -0400 Received: from mail-ie0-f174.google.com ([209.85.223.174]:61494 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754725Ab2JBQOC (ORCPT ); Tue, 2 Oct 2012 12:14:02 -0400 Date: Tue, 2 Oct 2012 12:14:24 -0400 From: Matt Porter To: Sekhar Nori Cc: Linux DaVinci Kernel List , Russell King , Benoit Cousson , Tony Lindgren , Greg Kroah-Hartman , Paul Walmsley , Linux Kernel Mailing List , "Hans J. Koch" , Linux OMAP List , Linux ARM Kernel List Subject: Re: [PATCH v2 4/7] ARM: davinci: Add support for an L3RAM gen_pool Message-ID: <20121002161424.GP5641@beef> References: <1348861072-14507-1-git-send-email-mporter@ti.com> <1348861072-14507-5-git-send-email-mporter@ti.com> <506986B2.1030000@ti.com> <20121001123242.GJ5641@beef> <506ABBCF.8010009@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <506ABBCF.8010009@ti.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3444 Lines: 74 On Tue, Oct 02, 2012 at 03:32:55PM +0530, Sekhar Nori wrote: > On 10/1/2012 6:02 PM, Matt Porter wrote: > > On Mon, Oct 01, 2012 at 05:34:02PM +0530, Sekhar Nori wrote: > >> Hi Matt, > >> > >> On 9/29/2012 1:07 AM, Matt Porter wrote: > >>> L3RAM (shared SRAM) is needed for use by several drivers. > >>> This creates a genalloc pool and a hook for the platform code > >>> to provide the struct gen_pool * in platform data. > >>> > >>> Signed-off-by: Matt Porter > >> > >> I am not sure if any of the DaVinci devices have a need to allocate from > >> *both* ARM RAM and shared RAM. Shared RAM is not present on all DaVinci > >> devices AFAIR, and on DA850, there is just 8KB ARM RAM so I am not sure > >> if there is much point in trying to allocate from there. > >> > >> Can you instead see if Ben's earlier patch[1] to use shared RAM for SRAM > >> allocation on DA850 makes sense for your case? If yes, can you repost > >> with Ben's patch included in your series instead of this patch? I would > >> prefer that over creating a new pool for shared RAM. > > > > Hrm, I did look at Ben's earlier patch. The reason I added a separate > > pool mostly was so I didn't have to touch the PM code at all. That can > > continue using the private SRAM API with the ARM RAM as it is now. The > > But you dont have to touch the PM code. PM code can continue using SRAM > API. I have verified in the past that PM can work using shared RAM. > > > idea here was to allow that to be separate since no other bus masters > > can access the ARM RAM anyway and do something that didn't require > > regression testing PM. Also, I figured there's really no reason to use > > even a tiny bit of the shared SRAM on PM if we have that ARM RAM there > > and working fine for that use case. > > I see no reason why PM would break with shared RAM. I have not even seen > reports of shared RAM being short of size so we need to save space by > having PM code in ARM RAM. I can test the changes before the code is > committed and it will get tested in linux-next as well. Ok, sounds good to me. > > The other thing is that Ben's patch needs to be rewritten to at least > > have the hook I added so we can provide the gen_pool in platform data. > > If you prefer this path still, I can add the needed hook on top of his > > original patch. Ultimately, I only *need* genalloc support for the > > shared sram so I can remove the private SRAM API from uio_pruss...so I'm > > happy with any way to get at it. > > Right, I prefer just adding the hook so that genalloc can be used along > with SRAM API. Ok. > > Oh, and to be honest...it's not just for uio_pruss, but also to cleanly > > remove the private SRAM API usage from the davinci ASoC driver too. > > Audio can use the shared RAM too. And once all users of the SRAM API are > gone, only the hook to help pass the gen_pool as platform data needs to > remain. Right, I think we are on the same page now. I'll post an update to Ben's original patch with required gen_pool hook for pdata use. I noticed the beginning of DT support for davinci and the DT-based genalloc driver, https://patchwork.kernel.org/patch/1421961/, fits into that well. -Matt -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/