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. Thanks, Minas -- 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
