[PATCH v2 3/4] USB: EHCI: improve interrupt qh unlink

Ming Lei ming.lei at canonical.com
Mon Jun 24 08:17:30 EDT 2013


On Mon, Jun 24, 2013 at 8:08 PM, Oliver Neukum <oliver at neukum.org> wrote:
> On Monday 24 June 2013 19:16:43 Ming Lei wrote:
>> On Mon, Jun 24, 2013 at 6:28 PM, Oliver Neukum <oliver at neukum.org> wrote:
>> > On Monday 24 June 2013 17:42:04 Ming Lei wrote:
>> >> This patch improves this above situation, and the qh will wait for 5
>> >> milliseconds before being unlinked from hardware, if one URB is submitted
>> >> during the period, the qh is move out of unlink wait list and the
>> >> interrupt transfer can be scheduled immediately, not like before: the
>> >> transfer is only linked to hardware until previous unlink is completed.
>> >
>> > It seems to me that this logic should be used only if the URB completed
>> > without error.
>>
>> The current completed URB with error  doesn't mean the later submitted
>> URB will complete with error, so I don't think the logic is related with URB
>> completion error.
>
> But
>
> a) it is likelier
> b) the driver will start error handling
>
> And what about the bandwidth? At least if you unlink the URB, its bandwidth
> should be given back immediately.

Yes, the patch doesn't affect unlinking intr URB because the
behavior of start_unlink_intr() isn't changed basically.

Thanks,
--
Ming Lei



More information about the linux-arm-kernel mailing list