Hi,
Paul Zimmerman <pauldzim@xxxxxxxxx> writes:
> Hi Felipe,
>
> Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> writes:
>
> < snip >
>
>> thinking about this a little more. This extra list_empty() check is
>> not wrong at all :-) I've amended this series with the 3 patches
>> below. I'll resend the series once I've given more time for people to
>> test. Patches have been updated to the branch on kernel.org as well,
>> btw.
>
> < snip >
>
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 9d4dc8bed644..9cf89f3cf203 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -1233,6 +1233,8 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
>> return DWC3_DSTS_SOFFN(reg);
>> }
>>
>> +#define DWC3_ALIGN_FRAME(d) (((d)->frame_number + (d)->interval) & ~((d)->interval - 1))
>> +
>> static void __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
>> {
>> if (list_empty(&dep->pending_list)) {
>> @@ -1242,11 +1244,7 @@ static void __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
>> return;
>> }
>>
>> - /*
>> - * Schedule the first trb for one interval in the future or at
>> - * least 4 microframes.
>> - */
>> - dep->frame_number += max_t(u32, 4, dep->interval);
>> + dep->frame_number = DWC3_ALIGN_FRAME(dep);
>> __dwc3_gadget_kick_transfer(dep);
>> }
>
> Pretty sure this could cause problems. Instead of starting at least 4 uframes
> in the future, this will now try to start at the next aligned uframe. If
> dep->interval is very small (say 1) and we are almost at the end of the
> current uframe, there might not be enough time?
perhaps, but I haven't seen that happen yet. Guess I'll get to this when
I see such a problem.
--
balbi
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