Re: [PATCH v14] tty: Fix the keyboard led light display problem

From: Dmitry Torokhov
Date: Wed Nov 10 2021 - 01:42:01 EST


Hi lianzhi,

On Mon, Nov 08, 2021 at 01:51:39PM +0800, lianzhi chang wrote:
> Switching from the desktop environment to the tty environment,
> the state of the keyboard led lights and the state of the keyboard
> lock are inconsistent. This is because the attribute kb->kbdmode
> of the tty bound in the desktop environment (Xorg) is set to
> VC_OFF, which causes the ledstate and kb->ledflagstate

We know that Xorg sets kbdmode mode to VC_OFF, but it does not mean that
you can say for sure that it is Xorg instance that controls a VT simply
by observing kb->kbdmode. There may be something else entirely. That is
why you want drivers/tty/vt/keyboard.c to reset LEDs and leave it to
whoever is controlling VT to set them to something else if it is
desired.

> values of the bound tty to always be 0, which causes the switch
> from the desktop When to the tty environment, the LED light
> status is inconsistent with the keyboard lock status.
> In order to ensure that the keyboard LED lights are displayed
> normally during the VT switching process, when the VT is
> switched, the current VT LED configuration is forced to be issued.
>
> Signed-off-by: lianzhi chang <changlianzhi@xxxxxxxxxxxxx>
> Suggested-by: dmitry.torokhov <dmitry.torokhov@xxxxxxxxx>
> Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
> v13:
> The kbd_bh function no longer handles the "kb->kbdmode == VC_OFF"
> scene, but puts this process in vt_set_leds_compute_shiftstate
> together. Because the current circumvention is that other ttys
> switch to the Xorg-bound tty scene, so this Better.
> v14:
> Sorry, I forgot to verify the format, it is good now.
>
> drivers/tty/vt/keyboard.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
> index c7fbbcdcc346..91e1c5d92029 100644
> --- a/drivers/tty/vt/keyboard.c
> +++ b/drivers/tty/vt/keyboard.c
> @@ -153,6 +153,7 @@ static int shift_state = 0;
>
> static unsigned int ledstate = -1U; /* undefined */
> static unsigned char ledioctl;
> +static bool vt_switch;
>
> /*
> * Notifier list for console keyboard events
> @@ -412,9 +413,20 @@ static void do_compute_shiftstate(void)
> /* We still have to export this method to vt.c */
> void vt_set_leds_compute_shiftstate(void)
> {
> + struct kbd_struct *kb;
> unsigned long flags;
>
> - set_leds();
> + /* Xorg will bind a tty, the kb->kbdmode of this tty will be set to
> + * VC_OFF, and this tty will no longer set the keyboard light. If
> + * there is no such restriction, when switching from other tty to
> + * Xorg-bound tty, the tty will set the keyboard light, which is
> + * unreasonable
> + */
> + kb = kbd_table + fg_console;
> + if (kb->kbdmode != VC_OFF) {
> + vt_switch = true;
> + set_leds();
> + }
>
> spin_lock_irqsave(&kbd_event_lock, flags);
> do_compute_shiftstate();
> @@ -1255,6 +1267,11 @@ static void kbd_bh(struct tasklet_struct *unused)
> leds |= (unsigned int)kbd->lockstate << 8;
> spin_unlock_irqrestore(&led_lock, flags);
>
> + if (vt_switch) {
> + ledstate = ~leds;
> + vt_switch = false;
> + }
> +
> if (leds != ledstate) {
> kbd_propagate_led_state(ledstate, leds);
> ledstate = leds;
> --
> 2.20.1
>
>
>

Thanks.

--
Dmitry