Hi, greg k-h, > > 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 scan_periodic start, that sitd is considered as out of date and is 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? Yes, we can, and the tests passed. > > If not, patches are always gladly accepted. We will trace more and have you updated. _If_ it is a kernel issue, I will be glad to build a patch. I do not suspect that at this moment. > > Also, you don't mention what kernel version you are testing this with... It is 2.6.30. Thanks, Julie. This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately. -- 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
