Re: [PATCH v3 1/2] media: videodev2: Add flags to unconditionnaly enumerate pixels formats
From: Benjamin Gaignard
Date: Mon Jul 15 2024 - 09:47:34 EST
Le 15/07/2024 à 15:37, Jacopo Mondi a écrit :
Hi Benjamin
On Mon, Jul 15, 2024 at 08:09:55AM GMT, Benjamin Gaignard wrote:
Le 12/07/2024 à 18:31, Jacopo Mondi a écrit :
Hi Benjamin
On Fri, Jul 12, 2024 at 12:29:59PM GMT, Benjamin Gaignard wrote:
Add new flags to enumerate all pixels formats when calling VIDIOC_ENUM_FMT ioctl.
When this V4L2_FMT_FLAG_ENUM_ALL_FORMATS flag is set drivers must
ignore the configuration and return the hardware supported pixel
formats for the specified queue.
To distinguish this particular enumeration case V4L2_FMT_FLAG_ALL_FORMATS
flag must be set by the drivers to highlight support of this feature
to user space applications.
This will permit to discover which pixel formats are supported
without setting codec-specific information so userland can more easily
know if the driver suits its needs well.
The main target are stateless decoders so update the documentation
about how to use this flag.
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
---
changes in version 3:
- Add a flag to inform userspace application that driver
as take care of the flag.
.../userspace-api/media/v4l/dev-stateless-decoder.rst | 6 ++++++
.../userspace-api/media/v4l/vidioc-enum-fmt.rst | 9 +++++++++
.../userspace-api/media/videodev2.h.rst.exceptions | 2 ++
drivers/media/v4l2-core/v4l2-ioctl.c | 3 +++
include/uapi/linux/videodev2.h | 2 ++
5 files changed, 22 insertions(+)
diff --git a/Documentation/userspace-api/media/v4l/dev-stateless-decoder.rst b/Documentation/userspace-api/media/v4l/dev-stateless-decoder.rst
index 35ed05f2695e..b0b657de910d 100644
--- a/Documentation/userspace-api/media/v4l/dev-stateless-decoder.rst
+++ b/Documentation/userspace-api/media/v4l/dev-stateless-decoder.rst
@@ -58,6 +58,12 @@ Querying capabilities
default values for these controls being used, and a returned set of formats
that may not be usable for the media the client is trying to decode.
+ * If the ``V4L2_FMT_FLAG_ENUM_ALL_FORMATS`` flag is set the driver must enumerate
+ all the supported formats without taking care of codec-dependent controls
+ set on the ``OUTPUT`` queue. To indicate that the driver has take care of this
+ flag it must set ``V4L2_FMT_FLAG_ALL_FORMATS`` flag for each format while
+ enumerating.
+
3. The client may use :c:func:`VIDIOC_ENUM_FRAMESIZES` to detect supported
resolutions for a given format, passing desired pixel format in
:c:type:`v4l2_frmsizeenum`'s ``pixel_format``.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
index 3adb3d205531..0399e0fc09b3 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
@@ -234,6 +234,15 @@ the ``mbus_code`` field is handled differently:
valid. The buffer consists of ``height`` lines, each having ``width``
Data Units of data and the offset (in bytes) between the beginning of
each two consecutive lines is ``bytesperline``.
+ * - ``V4L2_FMT_FLAG_ENUM_ALL_FORMATS``
+ - 0x0400
+ - Set by userland applications to enumerate all possible pixel formats
+ without taking care of any OUTPUT or CAPTURE queue configuration.
This seems to be only relevant for codecs and m2m devices.
For 'regular' capture (and I presume output) devices isn't the default
behaviour to enumerate all pixel formats, and userspace can decide to
restrict them by providing a media bus code (if the device reports the
V4L2_CAP_IO_MC capability)
Yes is targeting codecs because they have two queues.
Well, m2m devices in general then
When device have only one queue, like 'regular' capture devices,
pixel enumeration doesn't have to take care of the other queue
configuration because it doesn't exist.
This probably needs to be captured in the description here ?
We already have flags which apply only to some device types, and
that's specified in the flag description
* - ``V4L2_FMT_FLAG_CSC_QUANTIZATION``
- 0x0100
- The driver allows the application to try to change the default
quantization. This flag is relevant only for capture devices.
That makes sense I will update the flags description in the next version.
Thanks,
Benjamin
+ * - ``V4L2_FMT_FLAG_ALL_FORMATS``
+ - 0x0800
+ - Set by the driver to indicated that format have been enumerated because
+ :ref:`V4L2_FMT_FLAG_ENUM_ALL_FORMATS <v4l2-pix-fmt-flag-set-csc>` has
+ been set by the userland application.
Return Value
============
diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
index bdc628e8c1d6..7a3a1e9dc055 100644
--- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions
+++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions
@@ -216,6 +216,8 @@ replace define V4L2_FMT_FLAG_CSC_YCBCR_ENC fmtdesc-flags
replace define V4L2_FMT_FLAG_CSC_HSV_ENC fmtdesc-flags
replace define V4L2_FMT_FLAG_CSC_QUANTIZATION fmtdesc-flags
replace define V4L2_FMT_FLAG_META_LINE_BASED fmtdesc-flags
+replace define V4L2_FMT_FLAG_ENUM_ALL_FORMATS fmtdesc-flags
+replace define V4L2_FMT_FLAG_ALL_FORMATS fmtdesc-flags
# V4L2 timecode types
replace define V4L2_TC_TYPE_24FPS timecode-type
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 4c76d17b4629..5785a98b6ba2 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -1569,6 +1569,7 @@ static int v4l_enum_fmt(const struct v4l2_ioctl_ops *ops,
int ret = check_fmt(file, p->type);
u32 mbus_code;
u32 cap_mask;
+ u32 flags;
if (ret)
return ret;
@@ -1578,8 +1579,10 @@ static int v4l_enum_fmt(const struct v4l2_ioctl_ops *ops,
p->mbus_code = 0;
mbus_code = p->mbus_code;
+ flags = p->flags & V4L2_FMT_FLAG_ENUM_ALL_FORMATS;
memset_after(p, 0, type);
p->mbus_code = mbus_code;
+ p->flags = flags;
switch (p->type) {
case V4L2_BUF_TYPE_VIDEO_CAPTURE:
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index fe6b67e83751..b6a5da79ba21 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -886,6 +886,8 @@ struct v4l2_fmtdesc {
#define V4L2_FMT_FLAG_CSC_HSV_ENC V4L2_FMT_FLAG_CSC_YCBCR_ENC
#define V4L2_FMT_FLAG_CSC_QUANTIZATION 0x0100
#define V4L2_FMT_FLAG_META_LINE_BASED 0x0200
+#define V4L2_FMT_FLAG_ENUM_ALL_FORMATS 0x0400
+#define V4L2_FMT_FLAG_ALL_FORMATS 0x0800
/* Frame Size and frame rate enumeration */
/*
--
2.43.0