[PATCH] platform/x86: thinkpad_acpi: Don't register keyboard_lang unnecessarily

[PATCH] platform/x86: thinkpad_acpi: Don't register keyboard_lang unnecessarily

[Hans de Goede]

All recent ThinkPad BIOS-es support the GSKL method used to query the
keyboard-layout used by the ECFW for the SHIFT + other-key key-press
emulation for special keys such as e.g. the '=', '(' and ')' keys
above the numpad on 15" models.

So just checking for the method is not a good indicator of the
model supporting getting/setting the keyboard_lang.

On models where this is not supported GSKL succeeds, but it returns
METHOD_ERR in the returned integer to indicate that this is not
supported on this model.

Add a check for METHOD_ERR and return -ENODEV if it is set to
avoid registering a non-working keyboard_lang sysfs-attr on models
where this is not supported.

Cc: Nitin Joshi <njoshi1@lenovo.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/platform/x86/thinkpad_acpi.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index df2506974106..0b268e17cb7b 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -10356,6 +10356,13 @@ static int get_keyboard_lang(int *output)
 	if (!acpi_evalf(gskl_handle, &kbd_lang, NULL, "dd", 0x02000000))
 		return -EIO;
 
+	/*
+	 * METHOD_ERR gets returned on devices where there are no special (e.g. '=',
+	 * '(' and ')') keys which use layout dependent key-press emulation.
+	 */
+	if (kbd_lang & METHOD_ERR)
+		return -ENODEV;
+
 	*output = kbd_lang;
 
 	return 0;
-- 
2.29.2

Re: [PATCH] platform/x86: thinkpad_acpi: Don't register keyboard_lang unnecessarily

[Hans de Goede]

Hi,

On 1/25/21 9:52 PM, Hans de Goede wrote:
> All recent ThinkPad BIOS-es support the GSKL method used to query the
> keyboard-layout used by the ECFW for the SHIFT + other-key key-press
> emulation for special keys such as e.g. the '=', '(' and ')' keys
> above the numpad on 15" models.
> 
> So just checking for the method is not a good indicator of the
> model supporting getting/setting the keyboard_lang.
> 
> On models where this is not supported GSKL succeeds, but it returns
> METHOD_ERR in the returned integer to indicate that this is not
> supported on this model.
> 
> Add a check for METHOD_ERR and return -ENODEV if it is set to
> avoid registering a non-working keyboard_lang sysfs-attr on models
> where this is not supported.
> 
> Cc: Nitin Joshi <njoshi1@lenovo.com>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

I've applied this patch to my review-hans branch now,
so this should show up in platform-drivers-x86/for-next soon.

Regards,

Hans

> ---
>  drivers/platform/x86/thinkpad_acpi.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index df2506974106..0b268e17cb7b 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -10356,6 +10356,13 @@ static int get_keyboard_lang(int *output)
>  	if (!acpi_evalf(gskl_handle, &kbd_lang, NULL, "dd", 0x02000000))
>  		return -EIO;
>  
> +	/*
> +	 * METHOD_ERR gets returned on devices where there are no special (e.g. '=',
> +	 * '(' and ')') keys which use layout dependent key-press emulation.
> +	 */
> +	if (kbd_lang & METHOD_ERR)
> +		return -ENODEV;
> +
>  	*output = kbd_lang;
>  
>  	return 0;
>