Re: [PATCH v5 00/39] i.MX Media Driver

[Russell King - ARM Linux]

On Sun, Mar 12, 2017 at 08:40:37PM +0000, Russell King - ARM Linux wrote:
> On Sun, Mar 12, 2017 at 01:36:32PM -0700, Steve Longerbeam wrote:
> > But hold on, if my logic is correct, then why did the CSI power-off
> > get reached in your case, multiple times? Yes I think there is a bug,
> > link_notify() is not checking if the link has already been disabled.
> > I will fix this. But I'm surprised media core's link_notify handling
> > doesn't do this.
> 
> Well, I think there's something incredibly fishy going on here.  I
> turned that dev_dbg() at the top of the function into a dev_info(),
> and I get:
> 
> root@hbi2ex:~# dmesg |grep -A2 imx-ipuv3-csi
> [   53.370949] imx-ipuv3-csi imx-ipuv3-csi.0: power OFF
> [   53.371015] ------------[ cut here ]------------
> [   53.371075] WARNING: CPU: 0 PID: 1515 at drivers/staging/media/imx/imx-media-csi.c:806 csi_s_power+0xb8/0xd0 [imx_media_csi]
> --
> [   53.372624] imx-ipuv3-csi imx-ipuv3-csi.0: power OFF
> [   53.372637] ------------[ cut here ]------------
> [   53.372663] WARNING: CPU: 0 PID: 1515 at drivers/staging/media/imx/imx-media-csi.c:806 csi_s_power+0xb8/0xd0 [imx_media_csi]
> 
> There isn't a power on event being generated before these two power
> off events.  I don't see a power on event even when I attempt to
> start streaming either (which fails due to the lack of bayer
> support.)

Found it - my imx219 driver returns '1' from its s_power function when
powering up, which triggers a bug in your code - when imx_media_set_power()
fails to power up, you call imx_media_set_power() telling it to power
everything off - including devices that are already powered off.

This is really bad news - s_power() may be called via other paths,
such as when the subdev is opened.

-- 
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