Re: [PATCH v3 1/2] media: videodev2: Add flags to unconditionnaly enumerate pixels formats

From: Sebastian Fricke
Date: Wed Jul 10 2024 - 08:55:31 EST

Hey,

also this didn't reach patchwork because the mail address of the media
mailing list is wrong: linux-media@xxxxxxxxxxxxxx,

Regards,
Sebastian

On 10.07.2024 14:40, Sebastian Fricke wrote:
Hey Benjamin,

On 09.07.2024 18:17, Benjamin Gaignard wrote:
Add new flags to allow enumerate all pixels formats when

s/enumerate all pixels formats/enumeration of pixel formats,/

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 partical enumeration case V4L2_FMT_FLAG_ALL_FORMATS

s/partical/partiuclar/

flag must be set be drivers so user space applications can know that

s/be/by the/

drivers support this feature.

s/so user space applications can know that drivers support this feature./
, to highlight support for this feature to user space applications.

This will permit to discover which pixels formats are supported

s/pixels/pixel/

without setting codec-specific information so userland can more easily
knows if the driver suit well to what it needs.

s/knows/know/
s/suit well to what it needs/suits its needs well/

The main target are stateless decoders so update the documentation
about how use this flag.

s/how/how to/


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 | 10 ++++++++++
.../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, 23 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..de006a7fd02a 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 ``V4L2_FMT_FLAG_ENUM_ALL_FORMATS`` flag is set the driver must enumerate

s/If/If the/

+ all the supported formats without taking care of codec-dependent controls
+ set on ``OUTPUT`` queue. To indicate that the driver has take care of this

s/set on/set on the/
s/has take/has taken/

+ flag it must set ``V4L2_FMT_FLAG_ALL_FORMATS`` flag when it enumerates the

s/set/set the/
s/when it enumerates/for each format, while enumerating/
(to highlight that every enumerated format must carry the flag)

+ format.

s/format/formats/

+
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..510d2a6700aa 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst
@@ -234,6 +234,16 @@ 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 application to enumerate all possible pixels formats

s/application/applications/
s/pixels/pixel/

+ without taking care of any configuration done on OUTPUT or CAPTURE
+ queues.

s/any configuration done on OUTPUT or CAPTURE queues/
any OUTPUT or CAPTURE queue configuration/

+ * - ``V4L2_FMT_FLAG_ALL_FORMATS``
+ - 0x0800
+ - Set by driver to indicated that format has been enumerated because

s/driver to indicated that format has/
the driver to indicate, that formats have/

+ :ref:`V4L2_FMT_FLAG_ENUM_ALL_FORMATS <v4l2-pix-fmt-flag-set-csc>` has
+ been set by userland application.

s/by/by the/

Regards,
Sebastian


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

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