From 94ae1d6ba64c7157a6ba12a0deb7d8d7328fe4d5 Mon Sep 17 00:00:00 2001 From: Akinobu Mita Date: Sun, 20 May 2018 11:40:38 -0400 Subject: [PATCH] media: pxa_camera: avoid duplicate s_power calls The open() operation for the pxa_camera driver always calls s_power() operation to put its subdevice sensor in normal operation mode, and the release() operation always call s_power() operation to put the subdevice in power saving mode. This requires the subdevice sensor driver to keep track of its power state in order to avoid putting the subdevice in power saving mode while the device is still opened by some users. Many subdevice drivers handle it by the boilerplate code that increments and decrements an internal counter in s_power() like below: /* * If the power count is modified from 0 to != 0 or from != 0 to 0, * update the power state. */ if (sensor->power_count == !on) { ret = ov5640_set_power(sensor, !!on); if (ret) goto out; } /* Update the power count. */ sensor->power_count += on ? 1 : -1; However, some subdevice drivers don't handle it and may cause a problem with the pxa_camera driver if the video device is opened by more than two users at the same time. Instead of propagating the boilerplate code for each subdevice driver that implement s_power, this introduces an trick that many V4L2 drivers are using with v4l2_fh_is_singular_file(). Signed-off-by: Akinobu Mita Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- drivers/media/platform/pxa_camera.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/media/platform/pxa_camera.c b/drivers/media/platform/pxa_camera.c index c71a007..c792cb1 100644 --- a/drivers/media/platform/pxa_camera.c +++ b/drivers/media/platform/pxa_camera.c @@ -2040,6 +2040,9 @@ static int pxac_fops_camera_open(struct file *filp) if (ret < 0) goto out; + if (!v4l2_fh_is_singular_file(filp)) + goto out; + ret = sensor_call(pcdev, core, s_power, 1); if (ret) v4l2_fh_release(filp); @@ -2052,13 +2055,17 @@ static int pxac_fops_camera_release(struct file *filp) { struct pxa_camera_dev *pcdev = video_drvdata(filp); int ret; - - ret = vb2_fop_release(filp); - if (ret < 0) - return ret; + bool fh_singular; mutex_lock(&pcdev->mlock); - ret = sensor_call(pcdev, core, s_power, 0); + + fh_singular = v4l2_fh_is_singular_file(filp); + + ret = _vb2_fop_release(filp, NULL); + + if (fh_singular) + ret = sensor_call(pcdev, core, s_power, 0); + mutex_unlock(&pcdev->mlock); return ret; -- 2.7.4