Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752136AbdF0PpY (ORCPT ); Tue, 27 Jun 2017 11:45:24 -0400 Received: from mail-qt0-f179.google.com ([209.85.216.179]:35371 "EHLO mail-qt0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751501AbdF0PpQ (ORCPT ); Tue, 27 Jun 2017 11:45:16 -0400 MIME-Version: 1.0 In-Reply-To: References: <1498488673-27900-1-git-send-email-jacob-chen@iotwrt.com> From: Jacob Chen Date: Tue, 27 Jun 2017 23:45:14 +0800 Message-ID: Subject: Re: [PATCH 1/5] [media] rockchip/rga: v4l2 m2m support To: Tomasz Figa Cc: "linux-kernel@vger.kernel.org" , "open list:ARM/Rockchip SoC..." , "linux-arm-kernel@lists.infradead.org" , =?UTF-8?Q?Heiko_St=C3=BCbner?= , Linux Media Mailing List , Mauro Carvalho Chehab , Hans Verkuil Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 836 Lines: 26 Hi Tomasz, Yeah, the comments are wrong, i will correct it >> + */ >> + pages = (unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3); > > This is rather unfortunate and you should expect failures here on > actively used systems with uptime longer than few hours. Changing this > to dma_alloc_coherent() and enabling CMA _might_ give you a bit better > success rate, but... > > Normally, this kind of (scatter-gather capable) hardware would allow > some kind of linking of separate pages, e.g. last entry in the page > would point to the next page, or something like that. Doesn't this RGA > block have something similar? > Thx for pointing it out ! : ) I looked RGA drvier used in rockchip android and i find it use kmalloc, so i think it might support separate pages. I will test it. > Best regards, > Tomasz