[PATCH v5 0/21] usb: dwc2: host: Fix and speed up all the stuff, especially with splits

[Doug Anderson]

Heiko,

On Sat, Jan 23, 2016 at 9:52 AM, Heiko Stuebner <heiko at sntech.de> wrote:
> Hi,
>
> Am Freitag, 22. Januar 2016, 10:18:35 schrieb Douglas Anderson:
>> This is a bit of catchall series for all the bug fix and performance
>> patches I've been working on over the last few months.  Note that for
>> dwc2 we need to do LOTS in software and need super low interrupt
>> latency, so most performance improvements actually fix real bugs.
>>
>> Patches are structured to start with no-brainer stuff that could be
>> applied ASAP, especially things I've already gotten Acks for.  Things
>> get slightly more RFC / RFT like as we get farther down the series.
>> Anything that can be landed sooner rather than later (especially those
>> Acked long ago) would help in re-posts (I'm not biased, of course).
>>
>> It's been a few months since my last post of this series.  In the
>> meantime I've added a bunch of small bugfixes to the start of it and
>> also TOTALLY REWROTE the microframe scheduler.  I'll say up front: I
>> know nothing about USB.  I haven't read the whole spec.  I'm not
>> terribly familiar with the OHCI, EHCI, and XHCI drivers in the kernel.
>> ...and I'm pretty clueless overall.  Nevertheless, I've attempted to
>> write up a fancy scheduler based on the portion of the spec talking
>> about microframe scheduling requirements.  This rewritten scheduler does
>> seem to help when I start jamming lots of USB things into a hub, so
>> presumably the code is a reasonably starting point.  Given my current
>> understanding of USB the old code was fairly insane, so presumably even
>> if my new patch isn't perfect it's better than what we had.
>
> I've tested this series (+the low-speed fix from today) on the following
> usb-tree on a rk3288-veyron-jerry:
>
> /:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=ehci-platform/1p, 480M
>     |__ Port 1: Dev 2, If 0, Class=Video, Driver=, 480M
>     |__ Port 1: Dev 2, If 1, Class=Video, Driver=, 480M
> /:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=dwc2/1p, 480M
>     |__ Port 1: Dev 2, If 0, Class=Vendor Specific Class, Driver=zd1211rw, 480M
> /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dwc2/1p, 480M
>     |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/5p, 480M
>         |__ Port 1: Dev 3, If 0, Class=Vendor Specific Class, Driver=smsc95xx, 480M
>         |__ Port 3: Dev 4, If 0, Class=Hub, Driver=hub/4p, 480M
>             |__ Port 1: Dev 6, If 0, Class=Vendor Specific Class, Driver=, 12M
>             |__ Port 3: Dev 8, If 0, Class=Hub, Driver=hub/4p, 480M
>                 |__ Port 1: Dev 10, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
>                 |__ Port 1: Dev 10, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
>                 |__ Port 2: Dev 11, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
>                 |__ Port 2: Dev 11, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
>                 |__ Port 3: Dev 12, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
>                 |__ Port 4: Dev 13, If 0, Class=Mass Storage, Driver=usb-storage, 480M
>             |__ Port 4: Dev 9, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
>         |__ Port 4: Dev 5, If 0, Class=Mass Storage, Driver=usb-storage, 480M
>         |__ Port 5: Dev 7, If 0, Class=Mass Storage, Driver=usb-storage, 480M
>
>
> At first we were maxing out the 9 channels of the otg port, which the
> driver didn't seem to care about in 4.4-rc6, but after realizing that and
> switching over to the 16ch host-port it ran really nicely, especially wrt
> faster handling of all the keyboard input.

Actually, I should probably fix this in the patch ("usb: dwc2: host:
Totally redo the microframe scheduler").  While trying to make things
work originally I had moved the "dwc2_periodic_channel_available()" to
always happen even with the microframe scheduler, but I don't think
there's any strong reason for that.  I think we could just undo it and
everything would work just as well or better.

I'll try to do some testing with that fix next week and then try to
send up a spun series.  Note that the reason why ("usb: dwc2: host:
Totally redo the microframe scheduler") was near the end of the series
was that I'd expected that things earlier than it were in a pretty
good shape to land while I was expecting that the microframe rewrite
might need a spin or two.


> When looking over to the other desk and the person using that veyron-
> jerry not cursing anymore, it seem to be running fine in a real-world use
> for 2 hours now ;-)

Great news!  Thank you for testing!  :)

-Doug