Partially revert e31a0ba7df6ce21ac4ed58c4182ec12ca8fd78fb (media: Fix DVB devnode
representation at media controller) and 15d2042107f90f7ce39705716bc2c9a2ec1d5125
(Docbook: Fix documentation for media controller devnodes) commits.
Those commits mark the alsa struct in struct media_entity_desc as deprecated.
However, the alsa struct should remain as it is since it cannot be replaced
by a simple major/minor device node description. The alsa struct was designed
to be used as an alsa card description so V4L2 drivers could use this to expose
the alsa card that they create to carry the captured audio. Such a card is not
just a PCM device, but also needs to contain the alsa subdevice information,
and it may map to multiple devices, e.g. a PCM and a mixer device, such as the
au0828 usb stick creates.
This is exactly as intended and this cannot and should not be replaced by a
simple major/minor.
Updated the documentation as well to reflect this and to reinstate the 'major'
and 'minor' field documentation for the struct dev that was removed in the
original commit.
Updated the documentation to clearly state that struct dev is to be used for
(sub-)devices that create a single device node.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
diff --git a/Documentation/DocBook/media/v4l/media-ioc-enum-entities.xml b/Documentation/DocBook/media/v4l/media-ioc-enum-entities.xml
index cbf307f..8b22244 100644
--- a/Documentation/DocBook/media/v4l/media-ioc-enum-entities.xml
+++ b/Documentation/DocBook/media/v4l/media-ioc-enum-entities.xml
@@ -145,7 +145,49 @@
<entry>struct</entry>
<entry><structfield>dev</structfield></entry>
<entry></entry>
- <entry>Valid for (sub-)devices that create devnodes.</entry>
+ <entry>Valid for (sub-)devices that create a single device node.</entry>
+ </row>
+ <row>
+ <entry></entry>
+ <entry></entry>
+ <entry>__u32</entry>
+ <entry><structfield>major</structfield></entry>
+ <entry>Device node major number.</entry>
+ </row>
+ <row>
+ <entry></entry>
+ <entry></entry>
+ <entry>__u32</entry>
+ <entry><structfield>minor</structfield></entry>
+ <entry>Device node minor number.</entry>
+ </row>
+ <row>
+ <entry></entry>
+ <entry>struct</entry>
+ <entry><structfield>alsa</structfield></entry>
+ <entry></entry>
+ <entry>Valid for ALSA devices only.</entry>
+ </row>
+ <row>
+ <entry></entry>
+ <entry></entry>
+ <entry>__u32</entry>
+ <entry><structfield>card</structfield></entry>
+ <entry>ALSA card number</entry>
+ </row>
+ <row>
+ <entry></entry>
+ <entry></entry>
+ <entry>__u32</entry>
+ <entry><structfield>device</structfield></entry>
+ <entry>ALSA device number</entry>
+ </row>
+ <row>
+ <entry></entry>
+ <entry></entry>
+ <entry>__u32</entry>
+ <entry><structfield>subdevice</structfield></entry>
+ <entry>ALSA sub-device number</entry>
</row>
<row>
<entry></entry>
diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index d6d74bc..ec4e7ad 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -88,6 +88,11 @@ struct media_entity {
u32 major;
u32 minor;
} dev;
+ struct {
+ u32 card;
+ u32 device;
+ u32 subdevice;
+ } alsa;
/* Sub-device specifications */
/* Nothing needed yet */
diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
index 52cc2a6..34a10a5 100644
--- a/include/uapi/linux/media.h
+++ b/include/uapi/linux/media.h
@@ -88,6 +88,11 @@ struct media_entity_desc {
__u32 major;
__u32 minor;
} dev;
+ struct {
+ __u32 card;
+ __u32 device;
+ __u32 subdevice;
+ } alsa;
#if 1
/*
@@ -106,11 +111,6 @@ struct media_entity_desc {
__u32 major;
__u32 minor;
} fb;
- struct {
- __u32 card;
- __u32 device;
- __u32 subdevice;
- } alsa;
int dvb;
#endif
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