From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f177.google.com (mail-we0-f177.google.com [74.125.82.177]) by kanga.kvack.org (Postfix) with ESMTP id 79B5F6B0035 for ; Sat, 30 Nov 2013 05:00:28 -0500 (EST) Received: by mail-we0-f177.google.com with SMTP id p61so10042210wes.36 for ; Sat, 30 Nov 2013 02:00:27 -0800 (PST) Received: from mail-ea0-x22f.google.com (mail-ea0-x22f.google.com [2a00:1450:4013:c01::22f]) by mx.google.com with ESMTPS id uy8si26351002wjc.161.2013.11.30.02.00.27 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 30 Nov 2013 02:00:27 -0800 (PST) Received: by mail-ea0-f175.google.com with SMTP id z10so7359227ead.6 for ; Sat, 30 Nov 2013 02:00:27 -0800 (PST) Message-ID: From: Ivajlo Dimitrov References: <1847426616.52843.1383681351015.JavaMail.apache@mail83.abv.bg> Subject: Re: OMAPFB: CMA allocation failures Date: Sat, 30 Nov 2013 12:00:25 +0200 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="utf-8"; reply-type=original Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Tomi Valkeinen Cc: minchan@kernel.org, pavel@ucw.cz, sre@debian.org, pali.rohar@gmail.com, pc+n900@asdf.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Ping? ----- Original Message ----- From: "D?D2D?D1D>>D 3/4 D?D,D 1/4 D,N?N?D 3/4 D2" To: "Tomi Valkeinen" Cc: ; ; ; ; ; ; Sent: Tuesday, November 05, 2013 9:55 PM Subject: Re: OMAPFB: CMA allocation failures > > > > > > >-------- D?N?D,D3D,D 1/2 D?D>>D 1/2 D 3/4 D?D,N?D 1/4 D 3/4 -------- > >D?N?: Tomi Valkeinen > >D?N?D 1/2 D 3/4 N?D 1/2 D 3/4 : Re: OMAPFB: CMA allocation failures > >D?D 3/4 : D?D2D?D1D>>D 3/4 D?D,D 1/4 D,N?N?D 3/4 D2 > >D?D.D?N?D?N?DuD 1/2 D 3/4 D 1/2 D?: D!N?N?D'D?, 2013, D?DoN?D 3/4 D 1/4 D2N?D, 30 14:19:32 EET > > > >I really dislike the idea of adding the omap vram allocator back. Then > >again, if the CMA doesn't work, something has to be done. > > > > If I got Minchan Kim's explanation correctly, CMA simply can't be used > for allocation of framebuffer memory, because it is unreliable. > > >Pre-allocating is possible, but that won't work if there's any need to > >re-allocating the framebuffers. Except if the omapfb would retain and > >manage the pre-allocated buffers, but that would just be more or less > >the old vram allocator again. > > > >So, as I see it, the best option would be to have the standard dma_alloc > >functions get the memory for omapfb from a private pool, which is not > >used for anything else. > > > >I wonder if that's possible already? It sounds quite trivial to me. > > dma_alloc functions use either CMA or (iirc) get_pages_exact if CMA is > disabled. Both of those fail easily. AFAIK there are several > implementations with similar functionality, like CMEM and ION but > (correct me if I am wrong) neither of them is upstreamed. In the > current kernel I don't see anything that can be used for the purpose > of reliable allocation of big chunks of contiguous memory. > So, something should be done, but honestly, I can't think of anything > but bringing VRAM allocator back. Not that I like the idea of bringing > back ~700 lines of code, but I see no other option if omapfb driver is > to be actually useful. > > Regards, > Ivo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org