linux-kernel - Re: [PATCH v3 1/2] media: imx: csi: Disable SMFC before disabling IDMA channel

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Date:   Mon, 21 Jan 2019 10:21:08 -0500
From:   Gaël PORTAY <gael.portay@...labora.com>
To:     Philipp Zabel <p.zabel@...gutronix.de>
Cc:     Steve Longerbeam <slongerbeam@...il.com>,
        linux-media@...r.kernel.org, Peter Seiderer <ps.report@....net>,
        stable@...r.kernel.org, Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:STAGING SUBSYSTEM" <devel@...verdev.osuosl.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] media: imx: csi: Disable SMFC before disabling
 IDMA channel

Philipp,

On Mon, Jan 21, 2019 at 12:49:10PM +0100, Philipp Zabel wrote:
> Hi,
> 
> On Fri, 2019-01-18 at 17:04 -0800, Steve Longerbeam wrote:
> > Disable the SMFC before disabling the IDMA channel, instead of after,
> > in csi_idmac_unsetup().
> > 
> > This fixes a complete system hard lockup on the SabreAuto when streaming
> > from the ADV7180, by repeatedly sending a stream off immediately followed
> > by stream on:
> > 
> > while true; do v4l2-ctl  -d4 --stream-mmap --stream-count=3; done
> > 
> > Eventually this either causes the system lockup or EOF timeouts at all
> > subsequent stream on, until a system reset.
> > 
> > The lockup occurs when disabling the IDMA channel at stream off. Stopping
> > the video data stream entering the IDMA channel before disabling the
> > channel itself appears to be a reliable fix for the hard lockup. That can
> > be done either by disabling the SMFC or the CSI before disabling the
> > channel. Disabling the SMFC before the channel is the easiest solution,
> > so do that.
> > 
> > Fixes: 4a34ec8e470cb ("[media] media: imx: Add CSI subdev driver")
> > 
> > Suggested-by: Peter Seiderer <ps.report@....net>
> > Reported-by: Gaël PORTAY <gael.portay@...labora.com>
> > Signed-off-by: Steve Longerbeam <slongerbeam@...il.com>
> 
> Gaël, could we get a Tested-by: for this as well?
>

I have not tested the v3 yet. I have planned to do it later this day for
a all night testing and report the result then.

Gael