On 2025-01-28 00:03, Marek Vasut wrote:
On 1/27/25 11:42 PM, Dragan Simic wrote:
On 2025-01-27 23:23, Marek Vasut wrote:
On 1/27/25 11:20 PM, Dragan Simic wrote:
On 2025-01-27 22:55, Marek Vasut wrote:
On 1/19/25 7:50 PM, Dragan Simic wrote:
Selecting the CONFIG_SYS_CONSOLE_ENV_OVERWRITE option actually
prevents the
CONFIG_USB_KEYBOARD option from working as expected, i.e. USB
keyboards end
up not working as console inputs when "usbkbd" is properly
specified as part
of the value of the "stdin" environment variable. Describe this
clearly in
the two relevant Kconfig files, to prevent any possible confusion.
In more detail, the console_init_r() function ends up overwriting
the "stdin"
environment variable so it contains only the devices available at
that point
(which doesn't include "usbkbd"), while the "usb start" operation
is performed
much later, at which point the probe_usb_keyboard() function
cannot assign any
discovered USB keyboards to the console because "usbkbd" is no
longer present
in the "stdin" environment variable.
Wouldn't it be better to patch console_init_r() , check if "stdin"
variable contains 'usbkbd' and if so, start USB and register the
keyboard as stdin device at this point ? This is called after
relocation, so starting USB should be OK to do here. The behavior
should then be less confusing to users too.
Please correct me if I'm wrong, but isn't "usb start" deliberately
left to be executed as desired by the supported boards, or as part
of distroboot, i.e. in include/config_distro_bootcmd.h?
It is, but if the user needs USB keyboard as input device, shouldn't
we probe for that (which yes, will make the start up slower) ?
I agree that the way the whole thing works now, with or without this
patch, leaves a fair amount of room for confusion. That's exactly
how I felt while writing this patch -- I was confused a bit about
the possible outcomes of different combinations of the configuration
options. Though, I also felt that the way it works now also makes
the whole thing as flexible as possible, so the users can choose
whatever configuration they want, even the broken one.
I'm also afraid that, effectively, starting USB forcedly at that
point may cause some unforeseen issues or regressions.
It also crossed my mind that perhaps a good solution would be to
automatically deselect SYS_CONSOLE_ENV_OVERWRITE when the user
selects USB_KEYBOARD, because that's needed for USB keyboards to
actually work. That should also have lower potential for causing
some issues or regressions.
No, that's not good, users might want env overwrite to preconfigure
their input devices and USB keyboard support at the same time.
Indeed, I also don't like that approach very much. It would reduce
the flexibility of configuration options significantly.
Maybe another good option would be to modify the console_init_r()
function to simply leave "usbkbd" in the environment variables when
USB_KEYBOARD is selected, so the "usb start" executed later can
actually make USB keyboards work? I think such an approach should
have the lowest potential for causing some issues or regressions,
while it would pretty much eliminate any confusion.
Yes, this looks like the best option, because if 'usbkbd' is in
'stdin' environment variable, the user likely expects the USB keyboard
will show up later, but it is not available this early yet and
removing it from stdin variable would be unhelpful.
Please also update SYS_CONSOLE_ENV_OVERWRITE Kconfig symbol
description to reflect this change .
I'm glad that you like it, I'll move forward with that approach.
I was also thinking about making sure that "usbkbd" gets removed
from the "stdin" environment variable if there are actually no USB
keyboards detected during the "usb start", but that would actually
be wrong, because a USB keyboard should be detected after being
plugged in (in interactive mode, of course) after "usb start" is
executed, followed by executing "usb reset" on the UART console.
