linux-kernel - Re: [PATCH 1/2] omap3: ISP: Fix the failure of CCDC capture during suspend/resume

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <201108302307.47564.laurent.pinchart@ideasonboard.com>
Date:	Tue, 30 Aug 2011 23:07:47 +0200
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Deepthy Ravi <deepthy.ravi@...com>
Cc:	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	mchehab@...radead.org, linux-omap@...r.kernel.org,
	Abhilash K V <abhilash.kv@...com>
Subject: Re: [PATCH 1/2] omap3: ISP: Fix the failure of CCDC capture during suspend/resume

Hi,

On Wednesday 10 August 2011 16:03:12 Deepthy Ravi wrote:
> From: Abhilash K V <abhilash.kv@...com>
> 
> 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/