Re: [PATCH v2] [media] v4l2: add V4L2_CAP_IO_MC

From: Helen Koike
Date: Mon Jun 19 2017 - 13:49:51 EST

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In reply to: Hans Verkuil: "Re: [PATCH v2] [media] v4l2: add V4L2_CAP_IO_MC"
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Hi Hans,

Thanks for reviewing this

On 2017-06-19 08:15 AM, Hans Verkuil wrote:

On 06/14/2017 06:50 AM, Helen Koike wrote:

Add V4L2_CAP_IO_MC to be used in struct v4l2_capability to indicate that
input and output are controlled by the Media Controller instead of V4L2
API.
When this flag is set, ioctls for get, set and enum input and outputs
are automatically enabled and programmed to call helper function.

Signed-off-by: Helen Koike <helen.koike@xxxxxxxxxxxxx>

---

Changes in v2::
- replace the type by capability
- erase V4L2_INPUT_TYPE_DEFAULT
- also consider output
- plug helpers in the ops automatically so drivers doesn't need
to set it by hand
- update docs
- commit message and title
---
Documentation/media/uapi/v4l/vidioc-querycap.rst | 3 +
Documentation/media/videodev2.h.rst.exceptions | 1 +
drivers/media/v4l2-core/v4l2-dev.c | 35 +++++++--
drivers/media/v4l2-core/v4l2-ioctl.c | 91
++++++++++++++++++++++--
include/uapi/linux/videodev2.h | 2 +
5 files changed, 120 insertions(+), 12 deletions(-)

diff --git a/Documentation/media/uapi/v4l/vidioc-querycap.rst
b/Documentation/media/uapi/v4l/vidioc-querycap.rst
index 12e0d9a..2bd1223 100644
--- a/Documentation/media/uapi/v4l/vidioc-querycap.rst
+++ b/Documentation/media/uapi/v4l/vidioc-querycap.rst
@@ -252,6 +252,9 @@ specification the ioctl returns an ``EINVAL``
error code.
* - ``V4L2_CAP_TOUCH``
- 0x10000000
- This is a touch device.
+ * - ``V4L2_CAP_IO_MC``
+ - 0x20000000
+ - This device has its inputs and outputs controller by the
Media Controller

controller -> controlled

Sorry, I'll remember to use a spell checker next time

But I would rephrase this a bit:

- The inputs and/or outputs of this device are controlled by the
Media Controller
(see: <add link to Part IV of the media documentation>).

Sure, much better.
In this document, almost all the flags start with "The device supports..." or "The device has...", I was thinking to do something similar.

* - ``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 a5cb0a8..0b48cd0 100644
--- a/Documentation/media/videodev2.h.rst.exceptions
+++ b/Documentation/media/videodev2.h.rst.exceptions
@@ -159,6 +159,7 @@ replace define V4L2_CAP_ASYNCIO device-capabilities
replace define V4L2_CAP_STREAMING 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 c647ba6..0f272fe 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -688,22 +688,34 @@ 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_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 (vdev->device_caps & V4L2_CAP_IO_MC) {
+ set_bit(_IOC_NR(VIDIOC_ENUMINPUT), valid_ioctls);
+ set_bit(_IOC_NR(VIDIOC_G_INPUT), valid_ioctls);
+ set_bit(_IOC_NR(VIDIOC_S_INPUT), valid_ioctls);
+ } else {
+ 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);
+ }
}
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_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 (vdev->device_caps & V4L2_CAP_IO_MC) {
+ set_bit(_IOC_NR(VIDIOC_ENUMOUTPUT), valid_ioctls);
+ set_bit(_IOC_NR(VIDIOC_G_OUTPUT), valid_ioctls);
+ set_bit(_IOC_NR(VIDIOC_S_OUTPUT), valid_ioctls);
+ } else {
+ 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);
+ }
}
if (ops->vidioc_g_parm || (vdev->vfl_type ==
VFL_TYPE_GRABBER &&
ops->vidioc_g_std))
@@ -945,6 +957,17 @@ int __video_register_device(struct video_device
*vdev, int type, int nr,
video_device[vdev->minor] = vdev;
mutex_unlock(&videodev_lock);
+#if defined(CONFIG_MEDIA_CONTROLLER)
+ if (vdev->ioctl_ops
+ && !vdev->ioctl_ops->vidioc_enum_input
+ && !vdev->ioctl_ops->vidioc_s_input
+ && !vdev->ioctl_ops->vidioc_g_input
+ && !vdev->ioctl_ops->vidioc_enum_output
+ && !vdev->ioctl_ops->vidioc_s_output
+ && !vdev->ioctl_ops->vidioc_g_output)
+ vdev->device_caps |= V4L2_CAP_IO_MC;

No, this part should be dropped.

Let the driver set this capability explicitly. This code for example
would set the IO_MC
bit as well for radio devices, and that's not what you want.

hmm, right, so we will need to update the drivers one by one in the end.

I think I still don't fully understand the importance of the V4L2_CAP_IO_MC flag (sorry to bring this up again, I just want to make sure this is right), we don't have a flag to say that an output is an HDMI, user space uses the VIDIOC_ENUMOUTPUT ioctl to figure that this is an HDMI by its output's name, why this can't be the same for MC controlled IOs?

The MC can also be used by regular drivers (there is nothing preventing
drivers from
doing that). So just leave this up to the driver.

+#endif
+
if (vdev->ioctl_ops)
determine_valid_ioctls(vdev);
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c
b/drivers/media/v4l2-core/v4l2-ioctl.c
index e5a2187..9d8c645 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -1019,6 +1019,70 @@ static int v4l_querycap(const struct
v4l2_ioctl_ops *ops,
return ret;
}
+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 > 0)
+ return -EINVAL;
+
+ memset(i, 0, sizeof(*i));
+ strlcpy(i->name, vfd->name, sizeof(i->name));

i->type = V4L2_INPUT_TYPE_CAMERA;

+
+ return 0;
+}
+
+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 > 0)
+ return -EINVAL;
+
+ memset(o, 0, sizeof(*o));
+ strlcpy(o->name, vfd->name, sizeof(o->name));

o->type = V4L2_OUTPUT_TYPE_ANALOG;

+
+ return 0;
+}
+
+static int v4l2_ioctl_g_input_mc(struct file *file, void *priv,
unsigned int *i)
+{
+ *i = 0;
+ return 0;
+}
+#define v4l2_ioctl_g_output_mc v4l2_ioctl_g_input_mc
+
+static int v4l2_ioctl_s_input_mc(struct file *file, void *priv,
unsigned int i)
+{
+ return i ? -EINVAL : 0;
+}
+#define v4l2_ioctl_s_output_mc v4l2_ioctl_s_input_mc
+
+
+static int v4l_g_input(const struct v4l2_ioctl_ops *ops,
+ struct file *file, void *fh, void *arg)
+{
+ struct video_device *vfd = video_devdata(file);
+
+ if (vfd->device_caps & V4L2_CAP_IO_MC)
+ return v4l2_ioctl_g_input_mc(file, fh, arg);
+ else

'else' is not needed.

'else' is not needed but I thought it was easier to read the code this way (and I believe the compiler optimizes this), anyway, I'll remove the 'else' then, no problem.

+ 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)
+{
+ struct video_device *vfd = video_devdata(file);
+
+ if (vfd->device_caps & V4L2_CAP_IO_MC)
+ return v4l2_ioctl_g_output_mc(file, fh, arg);
+ else

'else' is not needed. Same for the others below.

+ 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)
{
@@ -1028,13 +1092,22 @@ static int v4l_s_input(const struct
v4l2_ioctl_ops *ops,
ret = v4l_enable_media_source(vfd);
if (ret)
return ret;
- return ops->vidioc_s_input(file, fh, *(unsigned int *)arg);
+
+ if (vfd->device_caps & V4L2_CAP_IO_MC)
+ return v4l2_ioctl_s_input_mc(file, fh, *(unsigned int *)arg);
+ else
+ 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)
{
- return ops->vidioc_s_output(file, fh, *(unsigned int *)arg);
+ struct video_device *vfd = video_devdata(file);
+
+ if (vfd->device_caps & V4L2_CAP_IO_MC)
+ return v4l2_ioctl_s_output_mc(file, fh, *(unsigned int *)arg);
+ else
+ return ops->vidioc_s_output(file, fh, *(unsigned int *)arg);
}
static int v4l_g_priority(const struct v4l2_ioctl_ops *ops,
@@ -1077,7 +1150,10 @@ static int v4l_enuminput(const struct
v4l2_ioctl_ops *ops,
if (is_valid_ioctl(vfd, VIDIOC_S_STD))
p->capabilities |= V4L2_IN_CAP_STD;
- return ops->vidioc_enum_input(file, fh, p);
+ if (vfd->device_caps & V4L2_CAP_IO_MC)
+ return v4l2_ioctl_enum_input_mc(file, fh, p);
+ else
+ return ops->vidioc_enum_input(file, fh, p);
}
static int v4l_enumoutput(const struct v4l2_ioctl_ops *ops,
@@ -1095,7 +1171,10 @@ static int v4l_enumoutput(const struct
v4l2_ioctl_ops *ops,
if (is_valid_ioctl(vfd, VIDIOC_S_STD))
p->capabilities |= V4L2_OUT_CAP_STD;
- return ops->vidioc_enum_output(file, fh, p);
+ if (vfd->device_caps & V4L2_CAP_IO_MC)
+ return v4l2_ioctl_enum_output_mc(file, fh, p);
+ else
+ return ops->vidioc_enum_output(file, fh, p);
}
static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
@@ -2534,11 +2613,11 @@ static struct v4l2_ioctl_info v4l2_ioctls[] = {
IOCTL_INFO_STD(VIDIOC_S_AUDIO, vidioc_s_audio, v4l_print_audio,
INFO_FL_PRIO),
IOCTL_INFO_FNC(VIDIOC_QUERYCTRL, v4l_queryctrl,
v4l_print_queryctrl, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_queryctrl, id)),
IOCTL_INFO_FNC(VIDIOC_QUERYMENU, v4l_querymenu,
v4l_print_querymenu, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_querymenu,
index)),
- IOCTL_INFO_STD(VIDIOC_G_INPUT, vidioc_g_input, v4l_print_u32, 0),
+ IOCTL_INFO_FNC(VIDIOC_G_INPUT, v4l_g_input, v4l_print_u32, 0),
IOCTL_INFO_FNC(VIDIOC_S_INPUT, v4l_s_input, v4l_print_u32,
INFO_FL_PRIO),
IOCTL_INFO_STD(VIDIOC_G_EDID, vidioc_g_edid, v4l_print_edid, 0),
IOCTL_INFO_STD(VIDIOC_S_EDID, vidioc_s_edid, v4l_print_edid,
INFO_FL_PRIO),
- IOCTL_INFO_STD(VIDIOC_G_OUTPUT, vidioc_g_output, v4l_print_u32, 0),
+ IOCTL_INFO_FNC(VIDIOC_G_OUTPUT, v4l_g_output, v4l_print_u32, 0),
IOCTL_INFO_FNC(VIDIOC_S_OUTPUT, v4l_s_output, v4l_print_u32,
INFO_FL_PRIO),
IOCTL_INFO_FNC(VIDIOC_ENUMOUTPUT, v4l_enumoutput,
v4l_print_enumoutput, INFO_FL_CLEAR(v4l2_output, index)),
IOCTL_INFO_STD(VIDIOC_G_AUDOUT, vidioc_g_audout,
v4l_print_audioout, 0),
diff --git a/include/uapi/linux/videodev2.h
b/include/uapi/linux/videodev2.h
index 2b8feb8..94cb196 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -460,6 +460,8 @@ 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 controler */

controler -> controller

+
#define V4L2_CAP_DEVICE_CAPS 0x80000000 /* sets device
capabilities field */
/*

Regards,

Hans

Thanks,
Helen

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In reply to: Hans Verkuil: "Re: [PATCH v2] [media] v4l2: add V4L2_CAP_IO_MC"
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