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SubjectRe: [PATCH v22] tty: Fix the keyboard led light display problem
On Wed, Dec 15, 2021 at 08:51:25PM +0800, lianzhi chang wrote:
> Use the "ctrl+alt+Fn" key combination to switch the system from tty to
> desktop or switch the system from desktop to tty. After the switch is
> completed, it is found that the state of the keyboard lock is
> inconsistent with the state of the keyboard Led light.The reasons are
> as follows:
>
> * The desktop environment (Xorg and other services) is bound to a tty
> (assuming it is tty1), and the kb->kbdmode attribute value of tty1
> will be set to VC_OFF. According to the current code logic, in the
> desktop environment, the values of ledstate and kb->ledflagstate
> of tty1 will not be modified anymore, so they are always 0.
>
> * When switching between each tty, the final value of ledstate set by
> the previous tty is compared with the kb->ledflagstate value of the
> current tty to determine whether to set the state of the keyboard
> light. The process of switching between desktop and tty is also the
> process of switching between tty1 and other ttys. There are two
> situations:
>
> - (1) In the desktop environment, tty1 will not set the ledstate,
> which will cause when switching from the desktop to other ttys,
> if the desktop lights up the keyboard's led, after the switch is
> completed, the keyboard's led light will always be on;
>
> - (2) When switching from another tty to the desktop, this
> mechanism will trigger tty1 to set the led state. If other tty
> lights up the led of the keyboard before switching to the desktop,
> the led will be forcibly turned off. This situation should
> be avoided.
>
> * The current patch is to solve these problems: When VT is switched,
> the keyboard led needs to be set once.Ensure that after the
> switch is completed, the state of the keyboard LED is consistent
> with the state of the keyboard lock.
>
> Signed-off-by: lianzhi chang <changlianzhi@uniontech.com>
> Suggested-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

> ---
> v22:
> Return to the v19 plan, remove the judgment condition in
> the vt_set_leds_compute_shiftstate() function.

Thank you for making the changes. The patch looks OK to me now.

>
> drivers/tty/vt/keyboard.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
> index c7fbbcdcc346..00283ba9a9e4 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
> @@ -414,6 +415,12 @@ void vt_set_leds_compute_shiftstate(void)
> {
> unsigned long flags;
>
> + /*
> + * When VT is switched, the keyboard led needs to be set once.
> + * Ensure that after the switch is completed, the state of the
> + * keyboard LED is consistent with the state of the keyboard lock.
> + */
> + vt_switch = true;
> set_leds();
>
> spin_lock_irqsave(&kbd_event_lock, flags);
> @@ -1255,6 +1262,11 @@ 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
>
>
>

--
Dmitry

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