[PATCH v4] platform/x86: dell-laptop: Fix bogus keyboard backlight sysfs interface

[PATCH v4] platform/x86: dell-laptop: Fix bogus keyboard backlight sysfs interface

[Kai-Heng Feng]

Dell Latitude 3160 does not have keyboard backlight, but there is a
sysfs interface for it, which does nothing at all.

KBD_LED_ON_TOKEN is the only token can be found. Since it doesn't have
KBD_LED_OFF_TOKEN or KBD_LED_AUTO_*_TOKEN, it should be safe to assume
at least two tokens should be present to support keyboard backlight.
Not all models have ON token - they may have multiple AUTO tokens instead.

Models which do not use SMBIOS token to control keyboard backlight, also
have this issue. Brightness level is 0 on these models. Verified on Dell
Inspiron 3565.

Reports keyboard backlight is supported only when at least two modes are
present.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---

v4:
Change commit log - not all models have ON token.

v3:
Change the logic, there should be at least two modes present to claim it
supports backlight. Suggested by Pali Rohár.

v2:
The only token can be found is actually KBD_LED_ON_TOKEN, which is BIT(5),
instead of KBD_LED_OFF_TOKEN. Change commit log accordingly.

Use token bit to make the intention more clear.
Also consider kbd_mode_levels_count and kbd_info.levels, suggested by
Pali Rohár.

Use XOR to simplify the bitmask comparison, suggested by
Andy Shevchenko.

 drivers/platform/x86/dell-laptop.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index ec202094bd50..f42159fd2031 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -1510,7 +1510,11 @@ static void kbd_init(void)
 	ret = kbd_init_info();
 	kbd_init_tokens();
 
-	if (kbd_token_bits != 0 || ret == 0)
+	/*
+	 * Only supports keyboard backlight when it has at least two modes.
+	 */
+	if ((ret == 0 && (kbd_info.levels != 0 || kbd_mode_levels_count >= 2))
+	    || kbd_get_valid_token_counts() >= 2)
 		kbd_led_present = true;
 }
 
-- 
2.13.1

Re: [PATCH v4] platform/x86: dell-laptop: Fix bogus keyboard backlight sysfs interface

[Pali Rohár]

On Tuesday 20 June 2017 11:05:19 Kai-Heng Feng wrote:
> Dell Latitude 3160 does not have keyboard backlight, but there is a
> sysfs interface for it, which does nothing at all.
> 
> KBD_LED_ON_TOKEN is the only token can be found. Since it doesn't have
> KBD_LED_OFF_TOKEN or KBD_LED_AUTO_*_TOKEN, it should be safe to assume
> at least two tokens should be present to support keyboard backlight.
> Not all models have ON token - they may have multiple AUTO tokens instead.
> 
> Models which do not use SMBIOS token to control keyboard backlight, also
> have this issue. Brightness level is 0 on these models. Verified on Dell
> Inspiron 3565.
> 
> Reports keyboard backlight is supported only when at least two modes are
> present.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

Reviewed-by: Pali Rohár <pali.rohar@gmail.com>

> ---
> 
> v4:
> Change commit log - not all models have ON token.
> 
> v3:
> Change the logic, there should be at least two modes present to claim it
> supports backlight. Suggested by Pali Rohár.
> 
> v2:
> The only token can be found is actually KBD_LED_ON_TOKEN, which is BIT(5),
> instead of KBD_LED_OFF_TOKEN. Change commit log accordingly.
> 
> Use token bit to make the intention more clear.
> Also consider kbd_mode_levels_count and kbd_info.levels, suggested by
> Pali Rohár.
> 
> Use XOR to simplify the bitmask comparison, suggested by
> Andy Shevchenko.
> 
>  drivers/platform/x86/dell-laptop.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index ec202094bd50..f42159fd2031 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -1510,7 +1510,11 @@ static void kbd_init(void)
>  	ret = kbd_init_info();
>  	kbd_init_tokens();
>  
> -	if (kbd_token_bits != 0 || ret == 0)
> +	/*
> +	 * Only supports keyboard backlight when it has at least two modes.
> +	 */
> +	if ((ret == 0 && (kbd_info.levels != 0 || kbd_mode_levels_count >= 2))
> +	    || kbd_get_valid_token_counts() >= 2)
>  		kbd_led_present = true;
>  }
>  

-- 
Pali Rohár
pali.rohar@gmail.com

Re: [PATCH v4] platform/x86: dell-laptop: Fix bogus keyboard backlight sysfs interface

[Andy Shevchenko]

On Tue, Jun 20, 2017 at 6:05 AM, Kai-Heng Feng
<kai.heng.feng@canonical.com> wrote:
> Dell Latitude 3160 does not have keyboard backlight, but there is a
> sysfs interface for it, which does nothing at all.
>
> KBD_LED_ON_TOKEN is the only token can be found. Since it doesn't have
> KBD_LED_OFF_TOKEN or KBD_LED_AUTO_*_TOKEN, it should be safe to assume
> at least two tokens should be present to support keyboard backlight.
> Not all models have ON token - they may have multiple AUTO tokens instead.
>
> Models which do not use SMBIOS token to control keyboard backlight, also
> have this issue. Brightness level is 0 on these models. Verified on Dell
> Inspiron 3565.
>
> Reports keyboard backlight is supported only when at least two modes are
> present.
>

Pushed to testing, thanks!

> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
>
> v4:
> Change commit log - not all models have ON token.
>
> v3:
> Change the logic, there should be at least two modes present to claim it
> supports backlight. Suggested by Pali Rohár.
>
> v2:
> The only token can be found is actually KBD_LED_ON_TOKEN, which is BIT(5),
> instead of KBD_LED_OFF_TOKEN. Change commit log accordingly.
>
> Use token bit to make the intention more clear.
> Also consider kbd_mode_levels_count and kbd_info.levels, suggested by
> Pali Rohár.
>
> Use XOR to simplify the bitmask comparison, suggested by
> Andy Shevchenko.
>
>  drivers/platform/x86/dell-laptop.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index ec202094bd50..f42159fd2031 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -1510,7 +1510,11 @@ static void kbd_init(void)
>         ret = kbd_init_info();
>         kbd_init_tokens();
>
> -       if (kbd_token_bits != 0 || ret == 0)
> +       /*
> +        * Only supports keyboard backlight when it has at least two modes.
> +        */
> +       if ((ret == 0 && (kbd_info.levels != 0 || kbd_mode_levels_count >= 2))
> +           || kbd_get_valid_token_counts() >= 2)
>                 kbd_led_present = true;
>  }
>
> --
> 2.13.1
>



-- 
With Best Regards,
Andy Shevchenko