On Tue, Aug 25, 2009 at 03:02:01PM -0600, Julie Zhu wrote: > Hello, all, > > We found an issue with FS isochronous device that is connected to the > USB host controller through an HS hub. This is on an embedded PowerPC > platform using an FPGA-based USB host controller. This issue exists for > both FS isochronous IN and OUT transfers behind an HS hub. I bet, this area is quite messy, and lots of known issues still remain. > The test setup is that the application submits 50 maxp 1 transfers, with > polling interval 4ms. The periodic frame list has 256 elements. The > application submits 2 batches of transfers with 50 transfers each. Other > FS isochronous tests fail too if connected through an HS hub. > > Using direct connection, the test passes fine. However, if connected > through an HS hub, there are less than 100 transfers happen on the bus. > > What we found is that when connected through an HS hub, the periodic > schedule is enabled, and scan_periodic is called constantly. Our trace > show that the mark of last scanned frame entry, ehci->next_uframe, often > is the frame entry that software links a new sitd in, and when next > scan_periodic start, that sitd is considered as out of date and is > unlinked. > > I wonder whether the test setting is correct? Well, I guess the issue is if you can just drop the hub and use a direct connection to the root hub? If not, patches are always gladly accepted. Also, you don't mention what kernel version you are testing this with... thanks, greg k-h -- 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
