On 2/19/2018 12:51 PM, Marek Vasut wrote: > On 02/19/2018 09:19 AM, Minas Harutyunyan wrote: >> On 2/17/2018 12:07 AM, Marek Vasut wrote: >>> On 02/16/2018 06:59 AM, Minas Harutyunyan wrote: >>>> On 2/15/2018 5:20 PM, Mirza Krak wrote: >>>>> On 14 February 2018 at 13:07, Minas Harutyunyan >>>>> <Minas.Harutyunyan at synopsys.com> wrote: >>>>>> On 2/14/2018 12:57 PM, Mirza Krak wrote: >>>>>>> On 8 February 2018 at 14:53, Minas Harutyunyan >>>>>>> <Minas.Harutyunyan at synopsys.com> wrote: >>>>> >>>>> < snip > >>>>> >>>>>> >>>>>> I reviewed your interrupt count log again. About 140,000 interrupts in 2 >>>>>> seconds, obviously it's not SOF only interrupts. More probably, its NAK >>>>>> respond interrupts to SSPLIT/CSPLIT transactions. For this case I can >>>>>> recommend you to apply patch from Douglas Anderson: "[PATCH v2] usb: >>>>>> dwc2: host: Don't retry NAKed transactions right away" which already >>>>>> merged to 4.16-rc1. >>>>>> >>>>>> In your setups you see different behavior on different HUBs. Your HUBs >>>>>> have different "TT think time": 8 and 32. In USB2.0 spec "TT think time" >>>>>> described as follow "TT requires at most 8/32 FS bit times of inter >>>>>> transaction gap on a full-/low-speed downstream bus". So, your "worst" >>>>>> HUB with "TT think time"=8 sending more frequently SSPLIT/CSPLIT >>>>>> transactions which replied by NAK. As result you see about 4 time more >>>>>> interrupts comparing to "good" HUB. Could you please check interrupts >>>>>> count for "good" HUB and check "4 time" hypothesis. >>>>> >>>>> Did some further testing. The "good" HUB is actually as bad as the >>>>> "bad" HUB, and it was my setup that caused the different behavior. Did >>>>> not use the same devices etc. >>>>> >>>>> Once I made sure that the configuration and setup was the same on both >>>>> board I could see that the behaved similarly. And that is the >>>>> following interrupt load: >>>>> >>>>> - BT USB (FS) = ~80k interrupts / second >>>>> - Keyboard (FS) = ~80k interrupts / second >>>>> - WiFI USB (HS) = ~8k interrupts / second >>>>> >>>>> After applying the suggested patch [1], it is steady around 8k >>>>> interrupts / second no matter what device I connect (HS/FS, >>>>> HUB/NO-HUB). Which is acceptable and usable. >>>> >>>> Great! >>> >>> So 8k IRQs per second is what I should expect from this HW with HS >>> device attached, that's normal and cannot be reduced ? >>> >> If core acting as Host in Buffer DMA mode then 8k IRQs per second (SOF >> interrupts) is expected if connected device(s) has periodic endpoint. > > Is there a way to reduce that or is that the absolute minimum in HS mode? > We already discussed, in this email thread earlier, why SOF interrupts required and unmasked. Only in case when connected device with CTRL+BLK EP's only (like flash drive) and directly connected to cores root HUB, SOF's will be masked. Thanks, Minas
