Re: [PATCH 2/6] v4l: omap4iss: Add support for OMAP4 camera interface - Video devices

[Hans Verkuil <hverkuil@xs4all.nl>]

On 11/04/2013 12:28 AM, Laurent Pinchart wrote:
> Hi Hans,
> 
> Thank you for the review.
> 
> On Thursday 03 October 2013 08:54:19 Hans Verkuil wrote:
>> On 10/03/2013 01:55 AM, Laurent Pinchart wrote:
>>> From: Sergio Aguirre <sergio.a.aguirre@gmail.com>
>>>
>>> This adds a very simplistic driver to utilize the CSI2A interface inside
>>> the ISS subsystem in OMAP4, and dump the data to memory.
>>>
>>> Check Documentation/video4linux/omap4_camera.txt for details.
>>>
>>> This commit adds video devices support.
>>>
>>> Signed-off-by: Sergio Aguirre <sergio.a.aguirre@gmail.com>
>>>
>>> [Port the driver to v3.12-rc3, including the following changes
>>> - Don't include plat/ headers
>>> - Don't use cpu_is_omap44xx() macro
>>> - Don't depend on EXPERIMENTAL
>>> - Fix s_crop operation prototype
>>> - Update link_notify prototype
>>> - Rename media_entity_remote_source to media_entity_remote_pad]
>>>
>>> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>>> ---
>>>
>>>  drivers/staging/media/omap4iss/iss_video.c | 1129 +++++++++++++++++++++++
>>>  drivers/staging/media/omap4iss/iss_video.h |  201 +++++
>>>  2 files changed, 1330 insertions(+)
>>>  create mode 100644 drivers/staging/media/omap4iss/iss_video.c
>>>  create mode 100644 drivers/staging/media/omap4iss/iss_video.h
>>>
>>> diff --git a/drivers/staging/media/omap4iss/iss_video.c
>>> b/drivers/staging/media/omap4iss/iss_video.c new file mode 100644
>>> index 0000000..31f1b88
>>> --- /dev/null
>>> +++ b/drivers/staging/media/omap4iss/iss_video.c
>>
>> <snip>
>>
>>> +/* ---------------------------------------------------------------------
>>> + * V4L2 ioctls
>>> + */
>>> +
>>> +static int
>>> +iss_video_querycap(struct file *file, void *fh, struct v4l2_capability
>>> *cap) +{
>>> +	struct iss_video *video = video_drvdata(file);
>>> +
>>> +	strlcpy(cap->driver, ISS_VIDEO_DRIVER_NAME, sizeof(cap->driver));
>>> +	strlcpy(cap->card, video->video.name, sizeof(cap->card));
>>> +	strlcpy(cap->bus_info, "media", sizeof(cap->bus_info));
>>> +
>>> +	if (video->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
>>> +		cap->capabilities = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
>>> +	else
>>> +		cap->capabilities = V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_STREAMING;
>>
>> Set device_caps instead of capabilities and add:
>>
>> 	cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
> 
> Actually cap->capabilities should be V4L2_CAP_DEVICE_CAPS | V4L2_CAP_STREAMING 
> | V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_OUTPUT. I'll fix that.

You're right.

> 
>>> +
>>> +	return 0;
>>> +}
> 
> [snip]
> 
>>> +static int
>>> +iss_video_try_format(struct file *file, void *fh, struct v4l2_format
>>> *format) +{
>>> +	struct iss_video *video = video_drvdata(file);
>>> +	struct v4l2_subdev_format fmt;
>>> +	struct v4l2_subdev *subdev;
>>> +	u32 pad;
>>> +	int ret;
>>> +
>>> +	if (format->type != video->type)
>>> +		return -EINVAL;
>>> +
>>> +	subdev = iss_video_remote_subdev(video, &pad);
>>> +	if (subdev == NULL)
>>> +		return -EINVAL;
>>> +
>>> +	iss_video_pix_to_mbus(&format->fmt.pix, &fmt.format);
>>> +
>>> +	fmt.pad = pad;
>>> +	fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>>> +	ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &fmt);
>>> +	if (ret)
>>> +		return ret == -ENOIOCTLCMD ? -EINVAL : ret;
>>
>> Return ENOTTY instead of EINVAL. Even better, use v4l2_subdev_has_op() +
>> v4l2_disable_ioctl() to just disable ioctls based on the available subdev
>> ops in probe().
> 
> The remote subdev is required to implement the get_fmt() operation, otherwise 
> the ISS driver can't work at all. What about adding a v4l2_subdev_has_op() 
> check at probe time and removing the check here ?

That would be best, yes.

> 
>>> +
>>> +	iss_video_mbus_to_pix(video, &fmt.format, &format->fmt.pix);
>>> +	return 0;
>>> +}
> 
> [snip]
> 
>>> +static int
>>> +iss_video_enum_input(struct file *file, void *fh, struct v4l2_input
>>> *input)
>>> +{
>>> +	if (input->index > 0)
>>> +		return -EINVAL;
>>> +
>>> +	strlcpy(input->name, "camera", sizeof(input->name));
>>> +	input->type = V4L2_INPUT_TYPE_CAMERA;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int
>>> +iss_video_g_input(struct file *file, void *fh, unsigned int *input)
>>> +{
>>> +	*input = 0;
>>> +
>>> +	return 0;
>>> +}
>>
>> Also add s_input.
> 
> Shouldn't I remove enum_input and g_input instead ?

No. G/S/ENUM_INPUT ioctls are compulsory for video capture devices.

One thing I would like to do at some point in time is to add a few helper functions
for this. A lot of camera/TV drivers have just one input, so it would be trivial to
add helpers for that. I just never got around to that.

Regards,

	Hans