On 02/19/2018 11:11 AM, Minas Harutyunyan wrote: > 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@xxxxxxxxxxxx> wrote: >>>>>>> On 2/14/2018 12:57 PM, Mirza Krak wrote: >>>>>>>> On 8 February 2018 at 14:53, Minas Harutyunyan >>>>>>>> <Minas.Harutyunyan@xxxxxxxxxxxx> 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. That's the setup I have on Altera SoCFPGA, yet the SOFs are still present. -- Best regards, Marek Vasut -- 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
