path: root/Documentation/usb
diff options
authorPete Zaitcev <zaitcev@redhat.com>2011-02-03 22:01:36 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2011-02-04 11:46:57 -0800
commitd25bc4db723a44c097268b466ff74bfba4bcc4f3 (patch)
tree95d78f5ccb66cec86e74a536637710c5f33b75a6 /Documentation/usb
parentac8d67417816fa7c568b24a8f2891eb02e6d0462 (diff)
USB: usbmon: fix-up docs and text API for sparse ISO
This is based on a patch that Alan Stern wrote. It did the same simple thing in both text and binary cases. In the same time, Marton and I fixed the binary side properly, but this leaves the text to be fixed. It is not very important due to low maxium data size of text, but let's add it just for extra correctness. The pseudocode is too much to keep fixed up, and we have real code to be used as examples now, so let's drop it too. Signed-off-by: Pete Zaitcev <zaitcev@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation/usb')
1 files changed, 9 insertions, 33 deletions
diff --git a/Documentation/usb/usbmon.txt b/Documentation/usb/usbmon.txt
index 66f92d1194c1..a4efa0462f05 100644
--- a/Documentation/usb/usbmon.txt
+++ b/Documentation/usb/usbmon.txt
@@ -12,6 +12,10 @@ Controller Drivers (HCD). So, if HCD is buggy, the traces reported by
usbmon may not correspond to bus transactions precisely. This is the same
situation as with tcpdump.
+Two APIs are currently implemented: "text" and "binary". The binary API
+is available through a character device in /dev namespace and is an ABI.
+The text API is deprecated since 2.6.35, but available for convenience.
* How to use usbmon to collect raw text traces
Unlike the packet socket, usbmon has an interface which provides traces
@@ -162,39 +166,11 @@ Here is the list of words, from left to right:
not machine words, but really just a byte stream split into words to make
it easier to read. Thus, the last word may contain from one to four bytes.
The length of collected data is limited and can be less than the data length
- report in Data Length word.
-Here is an example of code to read the data stream in a well known programming
-class ParsedLine {
- int data_len; /* Available length of data */
- byte data[];
- void parseData(StringTokenizer st) {
- int availwords = st.countTokens();
- data = new byte[availwords * 4];
- data_len = 0;
- while (st.hasMoreTokens()) {
- 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);
- b = Integer.parseInt(
- data_str.substring(i*2, i*2 + 2),
- 16);
- if (b >= 128)
- b *= -1;
- data[data_len] = (byte) b;
- data_len++;
- }
- }
- }
+ reported in the Data Length word. In the case of an Isochronous input (Zi)
+ completion where the received data is sparse in the buffer, the length of
+ the collected data can be greater than the Data Length value (because Data
+ Length counts only the bytes that were received whereas the Data words
+ contain the entire transfer buffer).