This is a note to let you know that I've just added the patch titled
[media] pxa_camera: fix module remove codepath for v4l2 clock
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: pxa_camera-fix-module-remove-codepath-for-v4l2-clock.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Mon Apr 9 17:09:24 CEST 2018
From: Petr Cvek petr.cvek@tul.cz Date: Mon, 24 Apr 2017 22:51:58 -0300 Subject: [media] pxa_camera: fix module remove codepath for v4l2 clock
From: Petr Cvek petr.cvek@tul.cz
[ Upstream commit e3b4d10cc057522353c4a02f2f90dca6a52e006f ]
The conversion from soc_camera omitted a correct handling of the clock gating for a sensor. When the pxa_camera driver module was removed it tried to unregister clk, but this caused a similar warning:
WARNING: CPU: 0 PID: 6740 at drivers/media/v4l2-core/v4l2-clk.c:278 v4l2_clk_unregister(): Refusing to unregister ref-counted 0-0030 clock!
The clock was at time still refcounted by the sensor driver. Before the removing of the pxa_camera the clock must be dropped by the sensor driver. This should be triggered by v4l2_async_notifier_unregister() call which removes sensor driver module too, calls unbind() function and then tries to probe sensor driver again. Inside unbind() we can safely unregister the v4l2 clock as the sensor driver got removed. The original v4l2_clk_unregister() should be put inside test as the clock can be already unregistered from unbind(). If there was not any bound sensor the clock is still present.
The codepath is practically a copy from the old soc_camera. The bug was tested with a pxa_camera+ov9640 combination during the conversion of the ov9640 from the soc_camera.
Signed-off-by: Petr Cvek petr.cvek@tul.cz Tested-by: Robert Jarzmik robert.jarzmik@free.fr Signed-off-by: Hans Verkuil hans.verkuil@cisco.com Signed-off-by: Mauro Carvalho Chehab mchehab@s-opensource.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/media/platform/pxa_camera.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
--- a/drivers/media/platform/pxa_camera.c +++ b/drivers/media/platform/pxa_camera.c @@ -2169,6 +2169,12 @@ static void pxa_camera_sensor_unbind(str pxa_dma_stop_channels(pcdev);
pxa_camera_destroy_formats(pcdev); + + if (pcdev->mclk_clk) { + v4l2_clk_unregister(pcdev->mclk_clk); + pcdev->mclk_clk = NULL; + } + video_unregister_device(&pcdev->vdev); pcdev->sensor = NULL;
@@ -2495,7 +2501,13 @@ static int pxa_camera_remove(struct plat dma_release_channel(pcdev->dma_chans[1]); dma_release_channel(pcdev->dma_chans[2]);
- v4l2_clk_unregister(pcdev->mclk_clk); + v4l2_async_notifier_unregister(&pcdev->notifier); + + if (pcdev->mclk_clk) { + v4l2_clk_unregister(pcdev->mclk_clk); + pcdev->mclk_clk = NULL; + } + v4l2_device_unregister(&pcdev->v4l2_dev);
dev_info(&pdev->dev, "PXA Camera driver unloaded\n");
Patches currently in stable-queue which might be from petr.cvek@tul.cz are
queue-4.9/pxa_camera-fix-module-remove-codepath-for-v4l2-clock.patch