From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756785Ab1H3VH0 (ORCPT ); Tue, 30 Aug 2011 17:07:26 -0400 Received: from perceval.ideasonboard.com ([95.142.166.194]:46758 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756730Ab1H3VHV (ORCPT ); Tue, 30 Aug 2011 17:07:21 -0400 From: Laurent Pinchart To: Deepthy Ravi Subject: Re: [PATCH 1/2] omap3: ISP: Fix the failure of CCDC capture during suspend/resume Date: Tue, 30 Aug 2011 23:07:47 +0200 User-Agent: KMail/1.13.7 (Linux/2.6.37-gentoo-r3; KDE/4.7.0; x86_64; ; ) Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, mchehab@infradead.org, linux-omap@vger.kernel.org, Abhilash K V References: <1312984992-19315-1-git-send-email-deepthy.ravi@ti.com> In-Reply-To: <1312984992-19315-1-git-send-email-deepthy.ravi@ti.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <201108302307.47564.laurent.pinchart@ideasonboard.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wednesday 10 August 2011 16:03:12 Deepthy Ravi wrote: > From: Abhilash K V > > While resuming from the "suspended to memory" state, > occasionally CCDC fails to get enabled and thus fails > to capture frames any more till the next suspend/resume > is issued. > This is a race condition which happens only when a CCDC > frame-completion ISR is pending even as ISP device's > isp_pm_prepare() is getting called and only one buffer > is left on the DMA queue. > The DMA queue buffers are thus depleted which results in > its underrun.So when ISP resumes there are no buffers on > the queue (as the application which can issue buffers is > yet to resume) to start video capture. > This fix addresses this issue by dequeuing and enqueing > the last buffer in isp_pm_prepare() after its DMA gets > completed. Thus,when ISP resumes it always finds atleast > one buffer on the DMA queue - this is true if application > uses only 3 buffers. How is that problem specific to the CCDC ? Can't it be reproduce at the preview engine or resizer output as well ? -- Regards, Laurent Pinchart