On Thu, Jun 16, 2011 at 01:39:43PM -0400, Alan Stern wrote: > On Thu, 16 Jun 2011, Sarah Sharp wrote: > > > > > > Alan, does that seem correct? > > > > > > The description of the behavior of ehci-hcd and uhci-hcd is correct. > > > ohci-hcd behaves the same way too. And they all agree with the > > > behavior described in the kerneldoc for struct urb in > > > include/linux/usb.h. > > > > Ah, you mean this bit? > > > > * @status: This is read in non-iso completion functions to get the > > * status of the particular request. ISO requests only use it > > * to tell whether the URB was unlinked; detailed status for > > * each frame is in the fields of the iso_frame-desc. > > Right. There's also some more near the end: > > * Completion Callbacks: > * > * The completion callback is made in_interrupt(), and one of the first > * things that a completion handler should do is check the status field. > * The status field is provided for all URBs. It is used to report > * unlinked URBs, and status for all non-ISO transfers. It should not > * be examined before the URB is returned to the completion handler. > > > > Under the circumstances, the documentation file should be changed. > > > Sarah, can you do that along with the change to xhci-hcd? > > > > Sure. It feels like there should be a note about which values > > isochronous URBs might have in the urb->status field. The USB core is > > the only one that would be setting those, so which values would it set? > > uvcvideo tests for these error codes: > > > > case -ENOENT: /* usb_kill_urb() called. */ > > case -ECONNRESET: /* usb_unlink_urb() called. */ > > case -ESHUTDOWN: /* The endpoint is being disabled. */ > > case -EPROTO: /* Device is disconnected (reported by some > > * host controller). */ > > > > Are there any others. > > -EREMOTEIO, in the unlikely event that URB_SHORT_NOT_OK is set, but no > others.
Are you saying that the USB core will only set -EREMOTEIO for isochronous URBs? Or do you mean that in addition to the status values that uvcvideo checks, the USB core can also set -EREMOTEIO? > And I wasn't aware of that last one... Host controller drivers should > report -ESHUTDOWN to mean the device has been disconnected, not > -EPROTO. But usually HCD don't take these events into account when > determining URB status codes. The xHCI driver will return -ESHUTDOWN as a status for URBs when the host controller is dying. Sarah Sharp -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
