On Fri, Oct 11, 2013 at 07:30:17PM +0300, Xenia Ragiadakou wrote: > On 10/11/2013 11:40 AM, Xenia Ragiadakou wrote: > >[snip] > >The main reasons that made me come to this conclusion was the fact > >that Context Entries by being updated with a value other than the > >last valid endpoint will be inconsistent with the definition in > >xhci spec (revision 1.0 5/21/10) "Context Entries. This field > >identifies the index of the last valid Endpoint Context within > >this Device Context structure." and that in 6.4.3.8 Stop Endpoint > >Command TRB field definitions for Endpoint ID field it states that > >"Valid values are ‘1’ to Slot Context Context Entries", from which > >i hypothesize that when Context Entries are set with a smaller > >value a subsequent Stop Command to an endpoint with higher index > >will fail. > > > >I compile now to see if that actually can happen. However, the > >best person to answer this question is an xHC architect. Will the > >xHC take under consideration the value in Context Entries field of > >the Output Slot Context only when a Configure Endpoint command is > >issued or also for other commands in order to check if the > >endpoint affected by the command is a valid endpoint? > > > > To test if a smaller value will cause a problem, I reset first > endpoint 4 and, then, endpoint 3 so that the Context Entries field > get updated with the value 3 while the actual last valid endpoint is > 4. Did you happen to see what the Context Entries field in the Output Slot Context was after the command finished? I would expect it to remain at 4, even though the Context Entries field in the Input Slot Context would have been 3. > Endpoint 4 is a BULK OUT endpoint so I checked if I could write to > the device. I didn't experience any issues when writing. > Then, I issued a Stop Endpoint command to EP 4 and although its > number is higher than the number kept in Context Entries field, the > Stop Endpoint command completed successfully. > Then, I issued a Set TR Dequeue pointer command to EP 4 and also > completed successfully. > At last, I issued a Disable Slot command to see if all the Endpoint > Contexts for the slot will be disabled and not only those in the > range of Context Entries and indeed all of them were disabled. > > So, I guess that my changelog was unreasonably ominous and that the > patch can be dropped. Ok, I'll drop it, and notify the testers they don't need the second patch. > From the above it seems that xHC does not update with the vallue in > the Context Entries field of the Input Slot Context any internal > register used in determining currently valid endpoints. The Output Slot Context Entries should still reflect which endpoints the hardware thinks are currently valid. Sarah Sharp -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
