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

[Michal Suchánek]

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.

Thanks

Michal