usbfs: Add support for bulk stream ids

This patch makes it possible to specify a bulk stream id when submitting an urb using the async usbfs API. It overloads the number_of_packets usbdevfs_urb field for this. This is not pretty, but given other constraints it is the best we can do. The reasoning leading to this goes as follows: 1) We want to support bulk streams in the usbfs API 2) We do not want to extend the usbdevfs_urb struct with a new member, as that would mean defining new ioctl numbers for all async API ioctls + adding compat versions for the old ones (times 2 for 32 bit support) 3) 1 + 2 means we need to re-use an existing field 4) number_of_packets is only used for isoc urbs, and streams are bulk only so it is the best (and only) candidate for re-using Note that: 1) This patch only uses number_of_packets as stream_id if the app has actually allocated streams on the ep, so that old apps which may have garbage in there (as it was unused until now in the bulk case), will not break 2) This patch does not add support for allocating / freeing bulk-streams, that is done in a follow up patch

Hans de Goede committed 13 years ago

Commit 948cd8c1 parent b2d03eb2 files · +8 −1Browse files

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include/uapi/linux/usbdevice_fs.h+4−1

@@ -102,7 +102,10 @@ struct usbdevfs_urb { · 101 unmodified lines
102	102	int buffer_length;
103	103	int actual_length;
104	104	int start_frame;
105		− int number_of_packets;
	105	+ union {
	106	+ int number_of_packets; /* Only used for isoc urbs */
	107	+ unsigned int stream_id; /* Only used with bulk streams */
	108	+ };
106	109	int error_count;
107	110	unsigned int signr; /* signal to be sent on completion,
108	111	or 0 if none should be sent. */