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 ? -- Best regards, Marek Vasut
