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

[Simon Glass]

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 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