USB: Fix up URB error codes to reflect implementation.
Documentation/usb/error-codes.txt mentions that urb->status can be set to
-EXDEV, if the isochronous transfer was not fully completed. However, in
practice, EHCI, UHCI, and OHCI all only set -EXDEV in the individual frame
status, never in the URB status. Those host controller actually always
pass in a zero status to usb_hcd_giveback_urb, and rely on the core to set
the appropriate status value.
The xHCI driver ran into issues with the uvcvideo driver when it tried to
set -EXDEV in urb->status, because the driver refused to submit URBs, and
the userspace camera application's video froze.
Clean up the documentation to reflect the actual implementation.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
diff --git a/Documentation/usb/error-codes.txt b/Documentation/usb/error-codes.txt
index d83703e..b3f606b 100644
--- a/Documentation/usb/error-codes.txt
+++ b/Documentation/usb/error-codes.txt
@@ -76,6 +76,13 @@
reported. That's because transfers often involve several packets, so that
one or more packets could finish before an error stops further endpoint I/O.
+For isochronous URBs, the urb status value is non-zero only if the URB is
+unlinked, the device is removed, the host controller is disabled, or the total
+transferred length is less than the requested length and the URB_SHORT_NOT_OK
+flag is set. Completion handlers for isochronous URBs should only see
+urb->status set to zero, -ENOENT, -ECONNRESET, -ESHUTDOWN, or -EREMOTEIO.
+Individual frame descriptor status fields may report more status codes.
+
0 Transfer completed successfully
@@ -132,7 +139,7 @@
device removal events immediately.
-EXDEV ISO transfer only partially completed
- look at individual frame status for details
+ (only set in iso_frame_desc[n].status, not urb->status)
-EINVAL ISO madness, if this happens: Log off and go home