[PATCH v3] console: usb: kbd: Limit poll frequency to improve performance

[Simon Glass]

Hi Filip,

On Tue, 25 Apr 2023 at 06:36, Filip Žaludek <filip.zaludek at oracle.com> wrote:
>
>
>
> Hi Simon,
>
>
> On 4/19/23 03:49, Simon Glass wrote:
> > Hi Filip,
> >
> > On Tue, 11 Apr 2023 at 14:24, Filip Žaludek <filip.zaludek at oracle.com> wrote:
> >>
> >>
> >>
> >> On 2/8/23 20:01, Mark Kettenis wrote:
> >>>> Date: Wed, 8 Feb 2023 19:45:36 +0100
> >>>> From: Michal Suchánek <msuchanek at suse.de>
> >>>>
> >>>> Hello,
> >>>>
> >>>> On Wed, Jan 18, 2023 at 05:01:12PM +0100, Filip Žaludek wrote:
> >>>>>
> >>>>>
> >>>>> Hi Michal,
> >>>>>
> >>>>>    thanks for testing! Do you consider keyboard as working once it is detected without
> >>>>> 'usb_kbd usb_kbd: Timeout poll on interrupt endpoint', or judging from subsequent
> >>>>> typing? Note that issue is reproducible only in about 20% of reboots.
> >>>>
> >>>> I rely on keyboard input to boot so if it was 20% broken I would notice.
> >>>> I don't use the rPi all that much so if it was broken only a few
> >>>> % of the time there is a chance I would miss it.
> >>>>
> >>>> However, for me not typing on the keyboard during usb detection it is
> >>>> 100% not detected, typing on it during usb detection it is 100%
> >>>> detected.
> >>>>
> >>>> The timeout is limitation of the dwc2 controller handling of usb hubs.
> >>>>
> >>>> There might be a possibility to improve the driver so that it handles
> >>>> the condition but it might be that the Linux driver relies on a separate
> >>>> thread handling the controller which is not acceptable for u-boot.
> >>>>
> >>>> I am not usb expert and definitely not dwc2 expert so I cannot do more
> >>>> than workaround the current driver limitation.
> >>>>
> >>>>> For me I can always enter 'U-Boot>' shell, but then keyboard usually does not work.
> >>>>> And yes, resetting the usb controller with pressing a key afterwards will
> >>>>> finally break the keyboard. ('usb reset' typed from keyboard)
> >>>>> If you are Prague located I am ready to demonstrate what I am talking about.
> >>>>>
> >>>>>    Simon's keyboard detection is somewhat interfered by 'SanDisk USB Extreme Pro' detection,
> >>>>> printed complaints but keyboard still works..
> >>>>> 'usb_kbd usb_kbd: Timeout poll on interrupt endpoint' and 'Failed to get keyboard state from device 0c40:8000'
> >>>>> Btw. why from 0c40:8000 (ELMCU 2.4GHz receiver) when wired keyboard is 046d:c31c (Logitech Keyboard K120)?
> >>>>>
> >>>>>    What is supposed scenario for RPi3/u-boot/grub usb keyboard equipped users wanting to boot non-default?
> >>>>> Enter 'U-Boot>' shell to detect keyboard; type boot; select desired grub entry..?
> >>>>>
> >>>>> Reverting either from the two makes it non issue for me:
> >>>>> 'dwc2: use the nonblock argument in submit_int_msg'
> >>>>> commit 9dcab2c4d2cb50ab1864c818b82a72393c160236
> >>>>
> >>>> Without this booting from USB is not feasible because reading every
> >>>> block from the USB drive waits for the keyboard to time out.
> >>>>
> >>>>> 'console: usb: kbd: Limit poll frequency to improve performance'
> >>>>> commit 96991e652f541323a03c5b7e075d54a117091618
> >>>>
> >>>> No idea about this one, for me it doea not give any substantial
> >>>> difference in behavior.
> >>>
> >>> Reverting that commit leads to a significant slowdown loading a kernel
> >>> from disk with a usb keyboard connected.  The slowdown is somewhat
> >>> hardware dependent but on some systems loading the OpenBSD/arm64
> >>> kernel would take minutes instead of seconds.
> >>
> >>
> >> Hello,
> >>     I am about to dig more into this issue with proper tools, but failed to
> >> configure/compile trace functionality on RPi3 due to missing references
> >> to timer_early_get_count() and timer_early_get_rate().
> >
> > You could implement a proper timer driver for rpi.
> >
> >>
> >>    Is it possible/feasible to implement calls in CONFIG_SYS_ARCH_TIMER
> >> and/or CONFIG_SP804_TIMER?
> >
> > Yes
>
>
>   I am little bit missing here secret sauce, timer_early_get_count() and timer_early_get_rate()
> are not supposed to be implemented in arch/arm/cpu/armv8/generic_timer.c? But predestined for
> drivers/timer/sp804_timer.c?
>
> TIMER is required for common/board_f.c and common/board_r.c but it disables generic_timer..
> %< -----------------------------------------
> ifndef CONFIG_$(SPL_TPL_)TIMER
> obj-$(CONFIG_SYS_ARCH_TIMER) += generic_timer.o
> endif
> %< -----------------------------------------
> And obviously multiple definition of get_tbclk and get_ticks when forced to compile/link.

It seems from the above that if TIMER is enabled for a particular
U-Boot build phase, then generic_timer is not, and vice versa. I
suppose that is fair enough.

>
>
>
>
> >>
> >>    I would be grateful even for trace to generate function traces without
> >> timestamps. Is such nasty hack without timestamping supposed to work?
> >> Basically my intention is to trace 'usb reset'.
> >>
> >> Appreciate any hints/outlines how to proceed.
> >
> > I assume you mean CONFIG_TRACE. Yes, you could update it to support
> > writing a zero timestamp. See the add_ftrace() function.
> >
> > But better to add a driver if you can. It should not be difficult.
> >
> > Regards,
> > Simon
>
>   I am already happily timestamp tracing with borrowed functionality from generic_timer.c,
> albeit bypassing kbuild mechanism. It did not yet answered my usb polling questions,
> tracing report is polluted/overfilled.
>
>
>
> Instrumenting code thoughts:
> * It would be handy to -finstrument-functions only for desired objects.

The compiler probably doesn't support that, or at least we don't
support passing different compiler args to each file in U-Boot, other
than by manually hacking the Makefiles.

But I wonder if we could have a list of wildcards to match against the
function names?

> * It would be handy to have macro inverse to 'notrace' to mark only desired functions. Feasible?
> * gcc -finstrument-functions-exclude-file-list still pollutes tracing buffer.

I wonder why? You could check whether the filename includes a full
path, or something like that, so that it doesn't match. There will be
a reason.

>
> More Tracing in U-Boot thoughts:
> * There is proftool options discrepancy, documented {-c, -f, -m, -o, -t, -v}, implemented {-m, -p, -t, -v}.
> * Both types FUNCF_ENTRY and FUNCF_EXIT are marked as " <- " by proftool.

Yes, please send a patch or two to clean these up.

Regards,
Simon