[PATCH] USB: Patch to make usbmon to print control setup packets
Make usbmon to print Setup packets of Control transfers. This is useful
when debugging enumeration issues.
This is a change to the trace format which is not fully compatible.
A parser has to look at the data length word now. If that word is
a character like 's', read setup packet before proceeding with data.
I decided not to bump the API tag for this because not many such
parsers exist at this point.
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/Documentation/usb/usbmon.txt b/Documentation/usb/usbmon.txt
index 2f8431f..f1896ee 100644
--- a/Documentation/usb/usbmon.txt
+++ b/Documentation/usb/usbmon.txt
@@ -101,6 +101,13 @@
or 3 and 2 positions, correspondingly.
- URB Status. This field makes no sense for submissions, but is present
to help scripts with parsing. In error case, it contains the error code.
+ In case of a setup packet, it contains a Setup Tag. If scripts read a number
+ in this field, the proceed to read Data Length. Otherwise, they read
+ the setup packet before reading the Data Length.
+- Setup packet, if present, consists of 5 words: one of each for bmRequestType,
+ bRequest, wValue, wIndex, wLength, as specified by the USB Specification 2.0.
+ These words are safe to decode if Setup Tag was 's'. Otherwise, the setup
+ packet was present, but not captured, and the fields contain filler.
- Data Length. This is the actual length in the URB.
- Data tag. The usbmon may not always capture data, even if length is nonzero.
Only if tag is '=', the data words are present.
@@ -125,25 +132,31 @@
String data_str = st.nextToken();
int len = data_str.length() / 2;
int i;
+ int b; // byte is signed, apparently?! XXX
for (i = 0; i < len; i++) {
- data[data_len] = Byte.parseByte(
- data_str.substring(i*2, i*2 + 2),
- 16);
+ // data[data_len] = Byte.parseByte(
+ // data_str.substring(i*2, i*2 + 2),
+ // 16);
+ b = Integer.parseInt(
+ data_str.substring(i*2, i*2 + 2),
+ 16);
+ if (b >= 128)
+ b *= -1;
+ data[data_len] = (byte) b;
data_len++;
}
}
}
}
-This format is obviously deficient. For example, the setup packet for control
-transfers is not delivered. This will change in the future.
+This format may be changed in the future.
Examples:
-An input control transfer to get a port status:
+An input control transfer to get a port status.
-d74ff9a0 2640288196 S Ci:001:00 -115 4 <
-d74ff9a0 2640288202 C Ci:001:00 0 4 = 01010100
+d5ea89a0 3575914555 S Ci:001:00 s a3 00 0000 0003 0004 4 <
+d5ea89a0 3575914560 C Ci:001:00 0 4 = 01050000
An output bulk transfer to send a SCSI command 0x5E in a 31-byte Bulk wrapper
to a storage device at address 5: