linux-kernel - Re: [PATCH] input&tty: Fix the keyboard led light display problem

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Date:   Thu, 14 Oct 2021 11:20:28 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     lianzhi chang <changlianzhi@...ontech.com>
Cc:     linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
        jirislaby@...nel.org, andriy.shevchenko@...ux.intel.com,
        linux-input@...r.kernel.org, 282827961@...com
Subject: Re: [PATCH] input&tty: Fix the keyboard led light display problem

Hi lianzhi,

On Thu, Oct 14, 2021 at 03:16:27PM +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
> 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.
> 
> Signed-off-by: lianzhi chang <changlianzhi@...ontech.com>
> ---
>  drivers/input/input.c     |  7 ++++++-
>  drivers/tty/vt/keyboard.c | 30 +++++++++++++++++++++++++++++-
>  include/linux/kbd_kern.h  |  2 ++
>  3 files changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/input.c b/drivers/input/input.c
> index ccaeb2426385..43c09700bf68 100644
> --- a/drivers/input/input.c
> +++ b/drivers/input/input.c
> @@ -25,6 +25,7 @@
>  #include <linux/rcupdate.h>
>  #include "input-compat.h"
>  #include "input-poller.h"
> +#include <linux/kbd_kern.h>
>  
>  MODULE_AUTHOR("Vojtech Pavlik <vojtech@...e.cz>");
>  MODULE_DESCRIPTION("Input core");
> @@ -472,8 +473,12 @@ void input_inject_event(struct input_handle *handle,
>  
>  		rcu_read_lock();
>  		grab = rcu_dereference(dev->grab);
> -		if (!grab || grab == handle)
> +		if (!grab || grab == handle) {
>  			input_handle_event(dev, type, code, value);
> +
> +			if (type == EV_LED && code < LED_SCROLLL)
> +				update_value_ledstate(code, value);

No, we should not be putting hooks for tty/vt directly into input core.
The code in drivers/tty/vt/keyboard.c is getting all relevant input
events and should be able to keep the led state synchronized. Please
keep all the changes localized there.

Thanks.

-- 
Dmitry