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[media] v4l2: use __u32 rather than enums in ioctl() structs

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V4L2 uses the enum type in IOCTL arguments in IOCTLs that were defined until
the use of enum was considered less than ideal. Recently Rémi Denis-Courmont
brought up the issue by proposing a patch to convert the enums to unsigned:

<URL:http://www.spinics.net/lists/linux-media/msg46167.html>

This sparked a long discussion where another solution to the issue was
proposed: two sets of IOCTL structures, one with __u32 and the other with
enums, and conversion code between the two:

<URL:http://www.spinics.net/lists/linux-media/msg47168.html>

Both approaches implement a complete solution that resolves the problem. The
first one is simple but requires assuming enums and __u32 are the same in
size (so we won't break the ABI) while the second one is more complex and
less clean but does not require making that assumption.

The issue boils down to whether enums are fundamentally different from __u32
or not, and can the former be substituted by the latter. During the
discussion it was concluded that the __u32 has the same size as enums on all
archs Linux is supported: it has not been shown that replacing those enums
in IOCTL arguments would break neither source or binary compatibility. If no
such reason is found, just replacing the enums with __u32s is the way to go.

This is what this patch does. This patch is slightly different from Remi's
first RFC (link above): it uses __u32 instead of unsigned and also changes
the arguments of VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY.

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Sakari Ailus
2012-05-10 02:02:07 -03:00
committed by Mauro Carvalho Chehab
parent 121b3ddbe4
commit 6016af82ea
15 changed files with 75 additions and 66 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Documentation/DocBook/media/v4l/io.xml
+7 -5
View File
@@ -543,12 +543,13 @@ and can range from zero to the number of buffers allocated
with the &VIDIOC-REQBUFS; ioctl (&v4l2-requestbuffers; <structfield>count</structfield>) minus one.</entry>
</row>
<row>
<entry>&v4l2-buf-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry></entry>
<entry>Type of the buffer, same as &v4l2-format;
<structfield>type</structfield> or &v4l2-requestbuffers;
<structfield>type</structfield>, set by the application.</entry>
<structfield>type</structfield>, set by the application. See <xref
linkend="v4l2-buf-type" /></entry>
</row>
<row>
<entry>__u32</entry>
@@ -568,7 +569,7 @@ refers to an input stream, applications when an output stream.</entry>
linkend="buffer-flags" />.</entry>
</row>
<row>
<entry>&v4l2-field;</entry>
<entry>__u32</entry>
<entry><structfield>field</structfield></entry>
<entry></entry>
<entry>Indicates the field order of the image in the
@@ -630,11 +631,12 @@ bandwidth. These devices identify by not enumerating any video
standards, see <xref linkend="standard" />.</para></entry>
</row>
<row>
<entry>&v4l2-memory;</entry>
<entry>__u32</entry>
<entry><structfield>memory</structfield></entry>
<entry></entry>
<entry>This field must be set by applications and/or drivers
in accordance with the selected I/O method.</entry>
in accordance with the selected I/O method. See <xref linkend="v4l2-memory"
/></entry>
</row>
<row>
<entry>union</entry>
Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
+6 -4
View File
@@ -94,16 +94,18 @@ information.</para>
<entry>The number of buffers requested or granted.</entry>
</row>
<row>
<entry>&v4l2-memory;</entry>
<entry>__u32</entry>
<entry><structfield>memory</structfield></entry>
<entry>Applications set this field to
<constant>V4L2_MEMORY_MMAP</constant> or
<constant>V4L2_MEMORY_USERPTR</constant>.</entry>
<constant>V4L2_MEMORY_USERPTR</constant>. See <xref linkend="v4l2-memory"
/></entry>
</row>
<row>
<entry>&v4l2-format;</entry>
<entry>__u32</entry>
<entry><structfield>format</structfield></entry>
<entry>Filled in by the application, preserved by the driver.</entry>
<entry>Filled in by the application, preserved by the driver.
See <xref linkend="v4l2-format" />.</entry>
</row>
<row>
<entry>__u32</entry>
Documentation/DocBook/media/v4l/vidioc-cropcap.xml
+2 -2
View File
@@ -65,7 +65,7 @@ output.</para>
&cs-str;
<tbody valign="top">
<row>
<entry>&v4l2-buf-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>Type of the data stream, set by the application.
Only these types are valid here:
@@ -73,7 +73,7 @@ Only these types are valid here:
<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant>,
<constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>, and custom (driver
defined) types with code <constant>V4L2_BUF_TYPE_PRIVATE</constant>
and higher.</entry>
and higher. See <xref linkend="v4l2-buf-type" />.</entry>
</row>
<row>
<entry>struct <link linkend="v4l2-rect-crop">v4l2_rect</link></entry>
Documentation/DocBook/media/v4l/vidioc-enum-fmt.xml
+2 -2
View File
@@ -71,7 +71,7 @@ the application. This is in no way related to the <structfield>
pixelformat</structfield> field.</entry>
</row>
<row>
<entry>&v4l2-buf-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>Type of the data stream, set by the application.
Only these types are valid here:
@@ -81,7 +81,7 @@ Only these types are valid here:
<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE</constant>,
<constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>, and custom (driver
defined) types with code <constant>V4L2_BUF_TYPE_PRIVATE</constant>
and higher.</entry>
and higher. See <xref linkend="v4l2-buf-type" />.</entry>
</row>
<row>
<entry>__u32</entry>
Documentation/DocBook/media/v4l/vidioc-g-crop.xml
+2 -2
View File
@@ -100,14 +100,14 @@ changed and <constant>VIDIOC_S_CROP</constant> returns the
&cs-str;
<tbody valign="top">
<row>
<entry>&v4l2-buf-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>Type of the data stream, set by the application.
Only these types are valid here: <constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant>,
<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant>,
<constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>, and custom (driver
defined) types with code <constant>V4L2_BUF_TYPE_PRIVATE</constant>
and higher.</entry>
and higher. See <xref linkend="v4l2-buf-type" />.</entry>
</row>
<row>
<entry>&v4l2-rect;</entry>
Documentation/DocBook/media/v4l/vidioc-g-fmt.xml
+1 -1
View File
@@ -116,7 +116,7 @@ this ioctl.</para>
<colspec colname="c4" />
<tbody valign="top">
<row>
<entry>&v4l2-buf-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry></entry>
<entry>Type of the data stream, see <xref
Documentation/DocBook/media/v4l/vidioc-g-frequency.xml
+3 -3
View File
@@ -95,14 +95,14 @@ the &v4l2-output; <structfield>modulator</structfield> field and the
&v4l2-modulator; <structfield>index</structfield> field.</entry>
</row>
<row>
<entry>&v4l2-tuner-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>The tuner type. This is the same value as in the
&v4l2-tuner; <structfield>type</structfield> field. The type must be set
&v4l2-tuner; <structfield>type</structfield> field. See The type must be set
to <constant>V4L2_TUNER_RADIO</constant> for <filename>/dev/radioX</filename>
device nodes, and to <constant>V4L2_TUNER_ANALOG_TV</constant>
for all others. The field is not applicable to modulators, &ie; ignored
by drivers.</entry>
by drivers. See <xref linkend="v4l2-tuner-type" /></entry>
</row>
<row>
<entry>__u32</entry>
Documentation/DocBook/media/v4l/vidioc-g-parm.xml
+3 -2
View File
@@ -75,11 +75,12 @@ devices.</para>
&cs-ustr;
<tbody valign="top">
<row>
<entry>&v4l2-buf-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry></entry>
<entry>The buffer (stream) type, same as &v4l2-format;
<structfield>type</structfield>, set by the application.</entry>
<structfield>type</structfield>, set by the application. See <xref
linkend="v4l2-buf-type" /></entry>
</row>
<row>
<entry>union</entry>
Documentation/DocBook/media/v4l/vidioc-g-sliced-vbi-cap.xml
+1 -1
View File
@@ -148,7 +148,7 @@ using the &VIDIOC-S-FMT; ioctl as described in <xref
<structfield>service_lines</structfield>[1][0] to zero.</entry>
</row>
<row>
<entry>&v4l2-buf-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>Type of the data stream, see <xref
linkend="v4l2-buf-type" />. Should be
Documentation/DocBook/media/v4l/vidioc-g-tuner.xml
+1 -1
View File
@@ -107,7 +107,7 @@ user.<!-- FIXME Video inputs already have a name, the purpose of this
field is not quite clear.--></para></entry>
</row>
<row>
<entry>&v4l2-tuner-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry spanname="hspan">Type of the tuner, see <xref
linkend="v4l2-tuner-type" />.</entry>
Documentation/DocBook/media/v4l/vidioc-queryctrl.xml
+1 -1
View File
@@ -127,7 +127,7 @@ the first control with a higher ID. Drivers which do not support this
flag yet always return an &EINVAL;.</entry>
</row>
<row>
<entry>&v4l2-ctrl-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>Type of control, see <xref
linkend="v4l2-ctrl-type" />.</entry>
Documentation/DocBook/media/v4l/vidioc-reqbufs.xml
+4 -3
View File
@@ -92,18 +92,19 @@ streamoff.--></para>
<entry>The number of buffers requested or granted.</entry>
</row>
<row>
<entry>&v4l2-buf-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>Type of the stream or buffers, this is the same
as the &v4l2-format; <structfield>type</structfield> field. See <xref
linkend="v4l2-buf-type" /> for valid values.</entry>
</row>
<row>
<entry>&v4l2-memory;</entry>
<entry>__u32</entry>
<entry><structfield>memory</structfield></entry>
<entry>Applications set this field to
<constant>V4L2_MEMORY_MMAP</constant> or
<constant>V4L2_MEMORY_USERPTR</constant>.</entry>
<constant>V4L2_MEMORY_USERPTR</constant>. See <xref linkend="v4l2-memory"
/>.</entry>
</row>
<row>
<entry>__u32</entry>
Documentation/DocBook/media/v4l/vidioc-s-hw-freq-seek.xml
+3 -2
View File
@@ -73,10 +73,11 @@ same value as in the &v4l2-input; <structfield>tuner</structfield>
field and the &v4l2-tuner; <structfield>index</structfield> field.</entry>
</row>
<row>
<entry>&v4l2-tuner-type;</entry>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>The tuner type. This is the same value as in the
&v4l2-tuner; <structfield>type</structfield> field.</entry>
&v4l2-tuner; <structfield>type</structfield> field. See <xref
linkend="v4l2-tuner-type" /></entry>
</row>
<row>
<entry>__u32</entry>