On 05/11/2014 10:46 PM, Frank Schäfer wrote:
>
> Am 09.05.2014 11:17, schrieb Hans Verkuil:
>> Some comments for future improvements:
>>
>> On 03/24/2014 08:33 PM, Frank Schäfer wrote:
>>> Signed-off-by: Frank Schäfer <fschaefer....@googlemail.com>
>>> ---
>>> drivers/media/usb/em28xx/em28xx-camera.c | 4 +-
>>> drivers/media/usb/em28xx/em28xx-video.c | 160
>>> +++++++++++++++++++++----------
>>> drivers/media/usb/em28xx/em28xx.h | 8 +-
>>> 3 files changed, 116 insertions(+), 56 deletions(-)
>>>
>>> diff --git a/drivers/media/usb/em28xx/em28xx-camera.c
>>> b/drivers/media/usb/em28xx/em28xx-camera.c
>>> index 505e050..daebef3 100644
>>> --- a/drivers/media/usb/em28xx/em28xx-camera.c
>>> +++ b/drivers/media/usb/em28xx/em28xx-camera.c
>>> @@ -365,7 +365,7 @@ int em28xx_init_camera(struct em28xx *dev)
>>> dev->sensor_xtal = 4300000;
>>> pdata.xtal = dev->sensor_xtal;
>>> if (NULL ==
>>> - v4l2_i2c_new_subdev_board(&dev->v4l2_dev, adap,
>>> + v4l2_i2c_new_subdev_board(&dev->v4l2->v4l2_dev, adap,
>>> &mt9v011_info, NULL)) {
>>> ret = -ENODEV;
>>> break;
>>> @@ -422,7 +422,7 @@ int em28xx_init_camera(struct em28xx *dev)
>>> dev->sensor_yres = 480;
>>>
>>> subdev =
>>> - v4l2_i2c_new_subdev_board(&dev->v4l2_dev, adap,
>>> + v4l2_i2c_new_subdev_board(&dev->v4l2->v4l2_dev, adap,
>>> &ov2640_info, NULL);
>>> if (NULL == subdev) {
>>> ret = -ENODEV;
>>> diff --git a/drivers/media/usb/em28xx/em28xx-video.c
>>> b/drivers/media/usb/em28xx/em28xx-video.c
>>> index 45ad471..89947db 100644
>>> --- a/drivers/media/usb/em28xx/em28xx-video.c
>>> +++ b/drivers/media/usb/em28xx/em28xx-video.c
>>> @@ -189,10 +189,11 @@ static int em28xx_vbi_supported(struct em28xx *dev)
>>> */
>>> static void em28xx_wake_i2c(struct em28xx *dev)
>>> {
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, core, reset, 0);
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, video, s_routing,
>>> + struct v4l2_device *v4l2_dev = &dev->v4l2->v4l2_dev;
>>> + v4l2_device_call_all(v4l2_dev, 0, core, reset, 0);
>>> + v4l2_device_call_all(v4l2_dev, 0, video, s_routing,
>>> INPUT(dev->ctl_input)->vmux, 0, 0);
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, video, s_stream, 0);
>>> + v4l2_device_call_all(v4l2_dev, 0, video, s_stream, 0);
>>> }
>>>
>>> static int em28xx_colorlevels_set_default(struct em28xx *dev)
>>> @@ -952,7 +953,8 @@ int em28xx_start_analog_streaming(struct vb2_queue *vq,
>>> unsigned int count)
>>> f.type = V4L2_TUNER_RADIO;
>>> else
>>> f.type = V4L2_TUNER_ANALOG_TV;
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, s_frequency, &f);
>>> + v4l2_device_call_all(&dev->v4l2->v4l2_dev,
>>> + 0, tuner, s_frequency, &f);
>>> }
>>>
>>> dev->streaming_users++;
>>> @@ -1083,6 +1085,7 @@ static int em28xx_vb2_setup(struct em28xx *dev)
>>>
>>> static void video_mux(struct em28xx *dev, int index)
>>> {
>>> + struct v4l2_device *v4l2_dev = &dev->v4l2->v4l2_dev;
>>> dev->ctl_input = index;
>>> dev->ctl_ainput = INPUT(index)->amux;
>>> dev->ctl_aoutput = INPUT(index)->aout;
>>> @@ -1090,21 +1093,21 @@ static void video_mux(struct em28xx *dev, int index)
>>> if (!dev->ctl_aoutput)
>>> dev->ctl_aoutput = EM28XX_AOUT_MASTER;
>>>
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, video, s_routing,
>>> + v4l2_device_call_all(v4l2_dev, 0, video, s_routing,
>>> INPUT(index)->vmux, 0, 0);
>>>
>>> if (dev->board.has_msp34xx) {
>>> if (dev->i2s_speed) {
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, audio,
>>> + v4l2_device_call_all(v4l2_dev, 0, audio,
>>> s_i2s_clock_freq, dev->i2s_speed);
>>> }
>>> /* Note: this is msp3400 specific */
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, audio, s_routing,
>>> + v4l2_device_call_all(v4l2_dev, 0, audio, s_routing,
>>> dev->ctl_ainput, MSP_OUTPUT(MSP_SC_IN_DSP_SCART1), 0);
>>> }
>>>
>>> if (dev->board.adecoder != EM28XX_NOADECODER) {
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, audio, s_routing,
>>> + v4l2_device_call_all(v4l2_dev, 0, audio, s_routing,
>>> dev->ctl_ainput, dev->ctl_aoutput, 0);
>>> }
>>>
>>> @@ -1344,7 +1347,7 @@ static int vidioc_querystd(struct file *file, void
>>> *priv, v4l2_std_id *norm)
>>> struct em28xx_fh *fh = priv;
>>> struct em28xx *dev = fh->dev;
>>>
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, video, querystd, norm);
>>> + v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, video, querystd, norm);
>>>
>>> return 0;
>>> }
>>> @@ -1374,7 +1377,7 @@ static int vidioc_s_std(struct file *file, void
>>> *priv, v4l2_std_id norm)
>>> size_to_scale(dev, dev->width, dev->height, &dev->hscale, &dev->vscale);
>>>
>>> em28xx_resolution_set(dev);
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_std, dev->norm);
>>> + v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, core, s_std, dev->norm);
>>>
>>> return 0;
>>> }
>>> @@ -1388,7 +1391,7 @@ static int vidioc_g_parm(struct file *file, void
>>> *priv,
>>>
>>> p->parm.capture.readbuffers = EM28XX_MIN_BUF;
>>> if (dev->board.is_webcam)
>>> - rc = v4l2_device_call_until_err(&dev->v4l2_dev, 0,
>>> + rc = v4l2_device_call_until_err(&dev->v4l2->v4l2_dev, 0,
>>> video, g_parm, p);
>>> else
>>> v4l2_video_std_frame_period(dev->norm,
>>> @@ -1404,7 +1407,8 @@ static int vidioc_s_parm(struct file *file, void
>>> *priv,
>>> struct em28xx *dev = fh->dev;
>>>
>>> p->parm.capture.readbuffers = EM28XX_MIN_BUF;
>>> - return v4l2_device_call_until_err(&dev->v4l2_dev, 0, video, s_parm, p);
>>> + return v4l2_device_call_until_err(&dev->v4l2->v4l2_dev,
>>> + 0, video, s_parm, p);
>>> }
>>>
>>> static const char *iname[] = {
>>> @@ -1543,7 +1547,7 @@ static int vidioc_g_tuner(struct file *file, void
>>> *priv,
>>>
>>> strcpy(t->name, "Tuner");
>>>
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, g_tuner, t);
>>> + v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
>>> return 0;
>>> }
>>>
>>> @@ -1556,7 +1560,7 @@ static int vidioc_s_tuner(struct file *file, void
>>> *priv,
>>> if (0 != t->index)
>>> return -EINVAL;
>>>
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, s_tuner, t);
>>> + v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
>>> return 0;
>>> }
>>>
>>> @@ -1576,15 +1580,16 @@ static int vidioc_g_frequency(struct file *file,
>>> void *priv,
>>> static int vidioc_s_frequency(struct file *file, void *priv,
>>> const struct v4l2_frequency *f)
>>> {
>>> - struct v4l2_frequency new_freq = *f;
>>> - struct em28xx_fh *fh = priv;
>>> - struct em28xx *dev = fh->dev;
>>> + struct v4l2_frequency new_freq = *f;
>>> + struct em28xx_fh *fh = priv;
>>> + struct em28xx *dev = fh->dev;
>>> + struct em28xx_v4l2 *v4l2 = dev->v4l2;
>>>
>>> if (0 != f->tuner)
>>> return -EINVAL;
>>>
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, s_frequency, f);
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, g_frequency, &new_freq);
>>> + v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, s_frequency, f);
>>> + v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, g_frequency, &new_freq);
>>> dev->ctl_freq = new_freq.frequency;
>>>
>>> return 0;
>>> @@ -1602,7 +1607,8 @@ static int vidioc_g_chip_info(struct file *file, void
>>> *priv,
>>> if (chip->match.addr == 1)
>>> strlcpy(chip->name, "ac97", sizeof(chip->name));
>>> else
>>> - strlcpy(chip->name, dev->v4l2_dev.name, sizeof(chip->name));
>>> + strlcpy(chip->name,
>>> + dev->v4l2->v4l2_dev.name, sizeof(chip->name));
>>> return 0;
>>> }
>>>
>>> @@ -1814,7 +1820,7 @@ static int radio_g_tuner(struct file *file, void
>>> *priv,
>>>
>>> strcpy(t->name, "Radio");
>>>
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, g_tuner, t);
>>> + v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
>>>
>>> return 0;
>>> }
>>> @@ -1827,12 +1833,26 @@ static int radio_s_tuner(struct file *file, void
>>> *priv,
>>> if (0 != t->index)
>>> return -EINVAL;
>>>
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, s_tuner, t);
>>> + v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
>>>
>>> return 0;
>>> }
>>>
>>> /*
>>> + * em28xx_free_v4l2() - Free struct em28xx_v4l2
>>> + *
>>> + * @ref: struct kref for struct em28xx_v4l2
>>> + *
>>> + * Called when all users of struct em28xx_v4l2 are gone
>>> + */
>>> +void em28xx_free_v4l2(struct kref *ref)
>>> +{
>>> + struct em28xx_v4l2 *v4l2 = container_of(ref, struct em28xx_v4l2, ref);
>>> +
>>> + kfree(v4l2);
>>> +}
>>> +
>>> +/*
>>> * em28xx_v4l2_open()
>>> * inits the device and starts isoc transfer
>>> */
>>> @@ -1840,6 +1860,7 @@ static int em28xx_v4l2_open(struct file *filp)
>>> {
>>> struct video_device *vdev = video_devdata(filp);
>>> struct em28xx *dev = video_drvdata(filp);
>>> + struct em28xx_v4l2 *v4l2 = dev->v4l2;
>>> enum v4l2_buf_type fh_type = 0;
>>> struct em28xx_fh *fh;
>>>
>>> @@ -1888,10 +1909,11 @@ static int em28xx_v4l2_open(struct file *filp)
>>>
>>> if (vdev->vfl_type == VFL_TYPE_RADIO) {
>>> em28xx_videodbg("video_open: setting radio device\n");
>>> - v4l2_device_call_all(&dev->v4l2_dev, 0, tuner, s_radio);
>>> + v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, s_radio);
>>> }
>>>
>>> kref_get(&dev->ref);
>>> + kref_get(&v4l2->ref);
>> I never like these kref things. Especially for usb devices I strongly
>> recommend
>> using the release() callback from v4l2_device instead: this callback will
>> only
>> be called once all references to video_device nodes have been closed. In
>> other
>> words, only once all filehandles to /dev/videoX (and radio, vbi etc) are
>> closed
>> will the release callback be called.
>>
>> As such it is a perfect place to put the final cleanup, and there is no more
>> need
>> to mess around with krefs.
>
> The v4l2 submodule data struct can not be cleared before 1) the
> submodule is unloaded/unregistered AND 2) all users of all device nodes
> are gone.
Indeed. That's the whole point of the v4l2_device release callback. It's only
called after all devices are unregistered AND the last user of those device
nodes
close has gone.
Basically you are duplicating the v4l2_device functionality here since
v4l2_device
uses its own kref.
> Using a kref is much easier (and also safer) than dealing with
> non-trivial case checks in em28xx_v4l2_fini() and the v4l2_device
> release() callbacks.
You don't need any case checks in the release callback. All those checks are
already done for you.
> What we could do is to call kref_get() only one time at the first open()
> of a device node and kref_put() only at the last close().
> But it seems that this would just complicate the code without any real
> benefit.
>
>
>>> dev->users++;
>> The same for these user counters. You can use v4l2_fh_is_singular_file() to
>> check
>> if the file open is the first file. However, this function assumes that
>> v4l2_fh_add
>> has been called first.
>>
>> So for this driver it might be easier if we add a v4l2_fh_is_empty() to
>> v4l2-fh.c
>> so we can call this before v4l2_fh_add.
>>
>> For that matter, you can almost certainly remove struct em28xx_fh altogether.
>> The type field of that struct can be determined by vdev->vfl_type and 'dev'
>> can be
>> obtained via video_get_drvdata().
>
> Yes, fields "dev" and "type" can definitly be removed from struct em28xx_fh.
> Then struct v4l2_fh fh is the last member, but I didn't have the time
> yet to take a deeper look at it.
> At a first glance its usage seems to be incomplete/broken.
> There are no v4l2_fh_del() and v4l2_fh_exit() calls and I wonder who
> deallocates the structs memory !?
vb2_fop_release() calls v4l2_fh_release() which calls del/exit. I admit, it's
not obvious.
Regards,
Hans
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