Re: [PATCH v3 1/5] v4l2-dev/ioctl: Add V4L2_CAP_IO_MC

[Helen Koike <helen.koike@collabora.com>]

Hi Niklas,

On 1/12/20 9:24 PM, Niklas Söderlund wrote:
> Add a video device capability flag to indicate that its inputs and/or
> outputs are controlled by the Media Controller instead of the V4L2 API.
> When this flag is set, ioctl for enum inputs and outputs are
> automatically enabled and programmed to call a helper function.
> 
> As a bonus fallback default handlers for VIDIOC_{G,S}_{INPUT,OUTPUT} are
> provided which can be used by drivers who only provide one input/output.
> Such drivers need just not declare vidioc_{g,s}_{input,output} in its
> struct v4l2_ioctl_ops and v4l2 will fallback to the single input/output
> defaults.
> 
> Suggested-by: Hans Verkuil <hverkuil@xs4all.nl>
> Signed-off-by: Helen Koike <helen.koike@collabora.com>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> ---
> * Changes since v2
> - Merged the two patches touching V4L2 core stuff to a single patch.
> - Updated documentation for V4L2_CAP_IO_MC
> - Added is_io_mc bool in determine_valid_ioctls()
> - Folded or moved code closer to where it's used
> - Remove unneeded memset()
> - Use strscpy() instead of strlcpy()
> ---
>  .../media/uapi/v4l/vidioc-querycap.rst        |  5 ++
>  .../media/videodev2.h.rst.exceptions          |  1 +
>  drivers/media/v4l2-core/v4l2-dev.c            | 19 +++--
>  drivers/media/v4l2-core/v4l2-ioctl.c          | 69 +++++++++++++++++--
>  include/uapi/linux/videodev2.h                |  2 +
>  5 files changed, 86 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/media/uapi/v4l/vidioc-querycap.rst b/Documentation/media/uapi/v4l/vidioc-querycap.rst
> index 5f9930195d624c73..da17e0e3c6f9a571 100644
> --- a/Documentation/media/uapi/v4l/vidioc-querycap.rst
> +++ b/Documentation/media/uapi/v4l/vidioc-querycap.rst
> @@ -264,6 +264,11 @@ specification the ioctl returns an ``EINVAL`` error code.
>      * - ``V4L2_CAP_TOUCH``
>        - 0x10000000
>        - This is a touch device.
> +    * - ``V4L2_CAP_IO_MC``
> +      - 0x20000000
> +      - There is only one input and/or output seen from userspace. Which I/O
> +        entity is routed to the input/output is controlled by the Media
> +        Controller. See :ref:`media_controller`.
>      * - ``V4L2_CAP_DEVICE_CAPS``
>        - 0x80000000
>        - The driver fills the ``device_caps`` field. This capability can
> diff --git a/Documentation/media/videodev2.h.rst.exceptions b/Documentation/media/videodev2.h.rst.exceptions
> index cb6ccf91776e6b56..a625fb90e3a989a7 100644
> --- a/Documentation/media/videodev2.h.rst.exceptions
> +++ b/Documentation/media/videodev2.h.rst.exceptions
> @@ -176,6 +176,7 @@ replace define V4L2_CAP_STREAMING device-capabilities
>  replace define V4L2_CAP_META_OUTPUT device-capabilities
>  replace define V4L2_CAP_DEVICE_CAPS device-capabilities
>  replace define V4L2_CAP_TOUCH device-capabilities
> +replace define V4L2_CAP_IO_MC device-capabilities
>  
>  # V4L2 pix flags
>  replace define V4L2_PIX_FMT_PRIV_MAGIC :c:type:`v4l2_pix_format`
> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
> index da42d172714adcb5..3c1a1200aa1fa9f3 100644
> --- a/drivers/media/v4l2-core/v4l2-dev.c
> +++ b/drivers/media/v4l2-core/v4l2-dev.c
> @@ -552,6 +552,7 @@ static void determine_valid_ioctls(struct video_device *vdev)
>  		       (vdev->device_caps & meta_caps);
>  	bool is_rx = vdev->vfl_dir != VFL_DIR_TX;
>  	bool is_tx = vdev->vfl_dir != VFL_DIR_RX;
> +	bool is_io_mc = vdev->device_caps & V4L2_CAP_IO_MC;
>  
>  	bitmap_zero(valid_ioctls, BASE_VIDIOC_PRIVATE);
>  
> @@ -725,22 +726,28 @@ static void determine_valid_ioctls(struct video_device *vdev)
>  		SET_VALID_IOCTL(ops, VIDIOC_G_STD, vidioc_g_std);
>  		if (is_rx) {
>  			SET_VALID_IOCTL(ops, VIDIOC_QUERYSTD, vidioc_querystd);
> -			SET_VALID_IOCTL(ops, VIDIOC_ENUMINPUT, vidioc_enum_input);
> -			SET_VALID_IOCTL(ops, VIDIOC_G_INPUT, vidioc_g_input);
> -			SET_VALID_IOCTL(ops, VIDIOC_S_INPUT, vidioc_s_input);
> +			set_bit(_IOC_NR(VIDIOC_G_INPUT), valid_ioctls);
> +			set_bit(_IOC_NR(VIDIOC_S_INPUT), valid_ioctls);

Maybe I'm reading this wrong, but from what I understand, in case where
(!is_io_mc && !ops->vidioc_enum_input) is true, shouldn't {G,S}_INPUT be invalid?
Same for output.

Also, if this is a MC device, the default with your patch is to enumerate one input and one output right?
I'm just wondering if vimc should be updated too, as it doesn't implement these ioctls.
(or other drivers who doesn't implement them).

Maybe I understood this wrong (very likely), but does it make sense to enumerate
output in a Capture node? Or to enumerate input in an Output node?

Regards,
Helen

>  			SET_VALID_IOCTL(ops, VIDIOC_ENUMAUDIO, vidioc_enumaudio);
>  			SET_VALID_IOCTL(ops, VIDIOC_G_AUDIO, vidioc_g_audio);
>  			SET_VALID_IOCTL(ops, VIDIOC_S_AUDIO, vidioc_s_audio);
>  			SET_VALID_IOCTL(ops, VIDIOC_QUERY_DV_TIMINGS, vidioc_query_dv_timings);
>  			SET_VALID_IOCTL(ops, VIDIOC_S_EDID, vidioc_s_edid);
> +			if (is_io_mc)
> +				set_bit(_IOC_NR(VIDIOC_ENUMINPUT), valid_ioctls);
> +			else
> +				SET_VALID_IOCTL(ops, VIDIOC_ENUMINPUT, vidioc_enum_input);
>  		}
>  		if (is_tx) {
> -			SET_VALID_IOCTL(ops, VIDIOC_ENUMOUTPUT, vidioc_enum_output);
> -			SET_VALID_IOCTL(ops, VIDIOC_G_OUTPUT, vidioc_g_output);
> -			SET_VALID_IOCTL(ops, VIDIOC_S_OUTPUT, vidioc_s_output);
> +			set_bit(_IOC_NR(VIDIOC_G_OUTPUT), valid_ioctls);
> +			set_bit(_IOC_NR(VIDIOC_S_OUTPUT), valid_ioctls);
>  			SET_VALID_IOCTL(ops, VIDIOC_ENUMAUDOUT, vidioc_enumaudout);
>  			SET_VALID_IOCTL(ops, VIDIOC_G_AUDOUT, vidioc_g_audout);
>  			SET_VALID_IOCTL(ops, VIDIOC_S_AUDOUT, vidioc_s_audout);
> +			if (is_io_mc)
> +				set_bit(_IOC_NR(VIDIOC_ENUMOUTPUT), valid_ioctls);
> +			else
> +				SET_VALID_IOCTL(ops, VIDIOC_ENUMOUTPUT, vidioc_enum_output);
>  		}
>  		if (ops->vidioc_g_parm || ops->vidioc_g_std)
>  			set_bit(_IOC_NR(VIDIOC_G_PARM), valid_ioctls);
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index aaf83e25427288fd..e8e15deeb8f36a9d 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1085,6 +1085,28 @@ static int v4l_querycap(const struct v4l2_ioctl_ops *ops,
>  	return ret;
>  }
>  
> +static int v4l_g_input(const struct v4l2_ioctl_ops *ops,
> +		       struct file *file, void *fh, void *arg)
> +{
> +	if (!ops->vidioc_g_input) {
> +		*(unsigned int *)arg = 0;
> +		return 0;
> +	}
> +
> +	return ops->vidioc_g_input(file, fh, arg);
> +}
> +
> +static int v4l_g_output(const struct v4l2_ioctl_ops *ops,
> +		       struct file *file, void *fh, void *arg)
> +{
> +	if (!ops->vidioc_g_output) {
> +		*(unsigned int *)arg = 0;
> +		return 0;
> +	}
> +
> +	return ops->vidioc_g_output(file, fh, arg);
> +}
> +
>  static int v4l_s_input(const struct v4l2_ioctl_ops *ops,
>  				struct file *file, void *fh, void *arg)
>  {
> @@ -1094,12 +1116,19 @@ static int v4l_s_input(const struct v4l2_ioctl_ops *ops,
>  	ret = v4l_enable_media_source(vfd);
>  	if (ret)
>  		return ret;
> +
> +	if (!ops->vidioc_s_input)
> +		return  *(unsigned int *)arg ? -EINVAL : 0;
> +
>  	return ops->vidioc_s_input(file, fh, *(unsigned int *)arg);
>  }
>  
>  static int v4l_s_output(const struct v4l2_ioctl_ops *ops,
>  				struct file *file, void *fh, void *arg)
>  {
> +	if (!ops->vidioc_s_output)
> +		return  *(unsigned int *)arg ? -EINVAL : 0;
> +
>  	return ops->vidioc_s_output(file, fh, *(unsigned int *)arg);
>  }
>  
> @@ -1128,6 +1157,20 @@ static int v4l_s_priority(const struct v4l2_ioctl_ops *ops,
>  	return v4l2_prio_change(vfd->prio, &vfh->prio, *p);
>  }
>  
> +static int v4l2_ioctl_enum_input_mc(struct file *file, void *priv,
> +				    struct v4l2_input *i)
> +{
> +	struct video_device *vfd = video_devdata(file);
> +
> +	if (i->index)
> +		return -EINVAL;
> +
> +	strscpy(i->name, vfd->name, sizeof(i->name));
> +	i->type = V4L2_INPUT_TYPE_CAMERA;
> +
> +	return 0;
> +}
> +
>  static int v4l_enuminput(const struct v4l2_ioctl_ops *ops,
>  				struct file *file, void *fh, void *arg)
>  {
> @@ -1143,9 +1186,26 @@ static int v4l_enuminput(const struct v4l2_ioctl_ops *ops,
>  	if (is_valid_ioctl(vfd, VIDIOC_S_STD))
>  		p->capabilities |= V4L2_IN_CAP_STD;
>  
> +	if (vfd->device_caps & V4L2_CAP_IO_MC)
> +		return v4l2_ioctl_enum_input_mc(file, fh, p);
> +
>  	return ops->vidioc_enum_input(file, fh, p);
>  }
>  
> +static int v4l2_ioctl_enum_output_mc(struct file *file, void *priv,
> +				     struct v4l2_output *o)
> +{
> +	struct video_device *vfd = video_devdata(file);
> +
> +	if (o->index)
> +		return -EINVAL;
> +
> +	strscpy(o->name, vfd->name, sizeof(o->name));
> +	o->type = V4L2_OUTPUT_TYPE_ANALOG;
> +
> +	return 0;
> +}
> +
>  static int v4l_enumoutput(const struct v4l2_ioctl_ops *ops,
>  				struct file *file, void *fh, void *arg)
>  {
> @@ -1161,6 +1221,9 @@ static int v4l_enumoutput(const struct v4l2_ioctl_ops *ops,
>  	if (is_valid_ioctl(vfd, VIDIOC_S_STD))
>  		p->capabilities |= V4L2_OUT_CAP_STD;
>  
> +	if (vfd->device_caps & V4L2_CAP_IO_MC)
> +		return v4l2_ioctl_enum_output_mc(file, fh, p);
> +
>  	return ops->vidioc_enum_output(file, fh, p);
>  }
>  
> @@ -2678,10 +2741,8 @@ DEFINE_V4L_STUB_FUNC(expbuf)
>  DEFINE_V4L_STUB_FUNC(g_std)
>  DEFINE_V4L_STUB_FUNC(g_audio)
>  DEFINE_V4L_STUB_FUNC(s_audio)
> -DEFINE_V4L_STUB_FUNC(g_input)
>  DEFINE_V4L_STUB_FUNC(g_edid)
>  DEFINE_V4L_STUB_FUNC(s_edid)
> -DEFINE_V4L_STUB_FUNC(g_output)
>  DEFINE_V4L_STUB_FUNC(g_audout)
>  DEFINE_V4L_STUB_FUNC(s_audout)
>  DEFINE_V4L_STUB_FUNC(g_jpegcomp)
> @@ -2730,11 +2791,11 @@ static const struct v4l2_ioctl_info v4l2_ioctls[] = {
>  	IOCTL_INFO(VIDIOC_S_AUDIO, v4l_stub_s_audio, v4l_print_audio, INFO_FL_PRIO),
>  	IOCTL_INFO(VIDIOC_QUERYCTRL, v4l_queryctrl, v4l_print_queryctrl, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_queryctrl, id)),
>  	IOCTL_INFO(VIDIOC_QUERYMENU, v4l_querymenu, v4l_print_querymenu, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_querymenu, index)),
> -	IOCTL_INFO(VIDIOC_G_INPUT, v4l_stub_g_input, v4l_print_u32, 0),
> +	IOCTL_INFO(VIDIOC_G_INPUT, v4l_g_input, v4l_print_u32, 0),
>  	IOCTL_INFO(VIDIOC_S_INPUT, v4l_s_input, v4l_print_u32, INFO_FL_PRIO),
>  	IOCTL_INFO(VIDIOC_G_EDID, v4l_stub_g_edid, v4l_print_edid, INFO_FL_ALWAYS_COPY),
>  	IOCTL_INFO(VIDIOC_S_EDID, v4l_stub_s_edid, v4l_print_edid, INFO_FL_PRIO | INFO_FL_ALWAYS_COPY),
> -	IOCTL_INFO(VIDIOC_G_OUTPUT, v4l_stub_g_output, v4l_print_u32, 0),
> +	IOCTL_INFO(VIDIOC_G_OUTPUT, v4l_g_output, v4l_print_u32, 0),
>  	IOCTL_INFO(VIDIOC_S_OUTPUT, v4l_s_output, v4l_print_u32, INFO_FL_PRIO),
>  	IOCTL_INFO(VIDIOC_ENUMOUTPUT, v4l_enumoutput, v4l_print_enumoutput, INFO_FL_CLEAR(v4l2_output, index)),
>  	IOCTL_INFO(VIDIOC_G_AUDOUT, v4l_stub_g_audout, v4l_print_audioout, 0),
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 5f9357dcb0602126..c793263a37052856 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -487,6 +487,8 @@ struct v4l2_capability {
>  
>  #define V4L2_CAP_TOUCH                  0x10000000  /* Is a touch device */
>  
> +#define V4L2_CAP_IO_MC			0x20000000  /* Is input/output controlled by the media controller */
> +
>  #define V4L2_CAP_DEVICE_CAPS            0x80000000  /* sets device capabilities field */
>  
>  /*
>