From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
During the 2012 Media Workshop it was decided that bus_info as returned
by VIDIOC_QUERYCAP can no longer be empty. It should be a unique identifier,
and empty strings are obviously not unique.
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
Documentation/DocBook/media/v4l/vidioc-querycap.xml | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/vidioc-querycap.xml b/Documentation/DocBook/media/v4l/vidioc-querycap.xml
index f33dd74..d5b1248 100644
--- a/Documentation/DocBook/media/v4l/vidioc-querycap.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-querycap.xml
@@ -90,11 +90,17 @@ ambiguities.</entry>
<entry>__u8</entry>
<entry><structfield>bus_info</structfield>[32]</entry>
<entry>Location of the device in the system, a
-NUL-terminated ASCII string. For example: "PCI Slot 4". This
+NUL-terminated ASCII string. For example: "PCI:0000:05:06.0". This
information is intended for users, to distinguish multiple
-identical devices. If no such information is available the field may
-simply count the devices controlled by the driver, or contain the
-empty string (<structfield>bus_info</structfield>[0] = 0).<!-- XXX pci_dev->slot_name example --></entry>
+identical devices. If no such information is available the field must
+simply count the devices controlled by the driver ("vivi-000"). The bus_info
+must start with "PCI:" for PCI boards, "PCIe:" for PCI Express boards,
+"usb-" for USB devices, "I2C:" for i2c devices, "ISA:" for ISA devices and
+"parport" for parallel port devices.
+For devices without a bus it should start with the driver name, optionally
+followed by "-" and an index if multiple instances of the device as possible.
+Many platform devices can have only one instance, so in that case bus_info
+is identical to the <structfield>driver</structfield> field.</entry>
</row>
<row>
<entry>__u32</entry>
--
1.7.10.4
--
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