Re: [PATCH v2 1/1] platform/x86: asus-wmi: add support for ASUS screenpad

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Fri, 5 May 2023, Luke D. Jones wrote:

> Add support for the WMI methods used to turn off and adjust the
> brightness of the secondary "screenpad" device found on some high-end
> ASUS laptops like the GX650P series and others.
> 
> These methods are utilised in a new backlight device named:
> - asus_screenpad
> 
> Signed-off-by: Luke D. Jones <luke@ljones.dev>
> ---
>  .../ABI/testing/sysfs-platform-asus-wmi       |   2 +-
>  drivers/platform/x86/asus-wmi.c               | 132 ++++++++++++++++++
>  drivers/platform/x86/asus-wmi.h               |   1 +
>  include/linux/platform_data/x86/asus-wmi.h    |   4 +
>  4 files changed, 138 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-platform-asus-wmi b/Documentation/ABI/testing/sysfs-platform-asus-wmi
> index a77a004a1baa..df9817c6233a 100644
> --- a/Documentation/ABI/testing/sysfs-platform-asus-wmi
> +++ b/Documentation/ABI/testing/sysfs-platform-asus-wmi
> @@ -97,4 +97,4 @@ Contact:	"Luke Jones" <luke@ljones.dev>
>  Description:
>  		Enable an LCD response-time boost to reduce or remove ghosting:
>  			* 0 - Disable,
> -			* 1 - Enable
> +			* 1 - Enable
> \ No newline at end of file

Spurious change?

> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index 1038dfdcdd32..0528eef02ef7 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -200,6 +200,7 @@ struct asus_wmi {
>  
>  	struct input_dev *inputdev;
>  	struct backlight_device *backlight_device;
> +	struct backlight_device *screenpad_backlight_device;
>  	struct platform_device *platform_device;
>  
>  	struct led_classdev wlan_led;
> @@ -3208,6 +3209,129 @@ static int is_display_toggle(int code)
>  	return 0;
>  }
>  
> +/* Screenpad backlight */
> +
> +static int read_screenpad_backlight_power(struct asus_wmi *asus)
> +{
> +	int ret = asus_wmi_get_devstate_simple(asus, ASUS_WMI_DEVID_SCREENPAD_POWER);

Please move this to own line because now you have the extra newline 
in between the call and error handling.

> +
> +	if (ret < 0)
> +		return ret;
> +	/* 1 == powered */
> +	return ret ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
> +}
> +
> +static int read_screenpad_brightness(struct backlight_device *bd)
> +{
> +	struct asus_wmi *asus = bl_get_data(bd);
> +	u32 retval;
> +	int err;
> +
> +	err = read_screenpad_backlight_power(asus);
> +	if (err < 0)
> +		return err;
> +	/* The device brightness can only be read if powered, so return stored */
> +	if (err == FB_BLANK_POWERDOWN)
> +		return asus->driver->screenpad_brightness;
> +
> +	err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_SCREENPAD_LIGHT, &retval);
> +	if (err < 0)
> +		return err;
> +
> +	return retval & ASUS_WMI_DSTS_BRIGHTNESS_MASK;
> +}
> +
> +static int update_screenpad_bl_status(struct backlight_device *bd)
> +{
> +	struct asus_wmi *asus = bl_get_data(bd);
> +	int power, err = 0;
> +	u32 ctrl_param;
> +
> +	power = read_screenpad_backlight_power(asus);
> +	if (power == -ENODEV)
> +		return err;

Just return 0. Or is there perhaps something wrong/missing here?

> +	else if (power < 0)
> +		return power;
> +
> +	if (bd->props.power != power) {
> +		if (power != FB_BLANK_UNBLANK) {
> +			/* Only brightness can power it back on */

Only brightness > 0 can power the screen back on

> +			ctrl_param = asus->driver->screenpad_brightness;

max(1, asus->driver->screenpad_brightness);

Don't forget to add the #include for it.

> +			/* Min 1 or the screen won't turn on */
> +			if (ctrl_param == 0)
> +				ctrl_param = 1;

Drop this.

> +			err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_LIGHT,
> +							ctrl_param, NULL);

Align param.

> +		} else {
> +			/* Ensure brightness is stored to turn back on with */
> +			asus->driver->screenpad_brightness = bd->props.brightness;
> +			err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_POWER, 0, NULL);
> +		}
> +	} else if (power == FB_BLANK_UNBLANK) {
> +		/* Only set brightness if powered on or we get invalid/unsync state */
> +		ctrl_param = bd->props.brightness;
> +		err = asus_wmi_set_devstate(ASUS_WMI_DEVID_SCREENPAD_LIGHT, ctrl_param, NULL);

Why not store the brightness if powered off?

> +	}
> +
> +	return err;
> +}
> +
> +static const struct backlight_ops asus_screenpad_bl_ops = {
> +	.get_brightness = read_screenpad_brightness,
> +	.update_status = update_screenpad_bl_status,
> +	.options = BL_CORE_SUSPENDRESUME,
> +};
> +
> +static int asus_screenpad_init(struct asus_wmi *asus)
> +{
> +	struct backlight_device *bd;
> +	struct backlight_properties props;
> +	int power, brightness;
> +
> +	power = read_screenpad_backlight_power(asus);
> +	if (power == -ENODEV)
> +		power = FB_BLANK_UNBLANK;
> +	else if (power < 0)
> +		return power;
> +
> +	memset(&props, 0, sizeof(struct backlight_properties));
> +	props.type = BACKLIGHT_RAW; /* ensure this bd is last to be picked */
> +	props.max_brightness = 255;
> +	bd = backlight_device_register("asus_screenpad",
> +				       &asus->platform_device->dev, asus,
> +				       &asus_screenpad_bl_ops, &props);
> +	if (IS_ERR(bd)) {
> +		pr_err("Could not register backlight device\n");
> +		return PTR_ERR(bd);
> +	}
> +
> +	asus->screenpad_backlight_device = bd;
> +
> +	brightness = read_screenpad_brightness(bd);
> +	if (brightness < 0)
> +		return brightness;
> +	/*
> +	 * Counter an odd behaviour where default is set to < 13 if it was 0 on boot.
> +	 * 60 is subjective, but accepted as a good compromise to retain visibility.
> +	 */
> +	else if (brightness < 60)

Since the other branch returns, else is unnecessary.

-- 
 i.

> +		brightness = 60;
> +
> +	asus->driver->screenpad_brightness = brightness;
> +	bd->props.brightness = brightness;
> +	bd->props.power = power;
> +	backlight_update_status(bd);
> +
> +	return 0;
> +}
> +
> +static void asus_screenpad_exit(struct asus_wmi *asus)
> +{
> +	backlight_device_unregister(asus->screenpad_backlight_device);
> +
> +	asus->screenpad_backlight_device = NULL;
> +}
> +
>  /* Fn-lock ********************************************************************/
>  
>  static bool asus_wmi_has_fnlock_key(struct asus_wmi *asus)
> @@ -3823,6 +3947,13 @@ static int asus_wmi_add(struct platform_device *pdev)
>  	} else if (asus->driver->quirks->wmi_backlight_set_devstate)
>  		err = asus_wmi_set_devstate(ASUS_WMI_DEVID_BACKLIGHT, 2, NULL);
>  
> +	if (asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_SCREENPAD_LIGHT)) {
> +		pr_warn("Begin asus_screenpad_init");
> +		err = asus_screenpad_init(asus);
> +		if (err && err != -ENODEV)
> +			goto fail_backlight;
> +	}
> +
>  	if (asus_wmi_has_fnlock_key(asus)) {
>  		asus->fnlock_locked = fnlock_default;
>  		asus_wmi_fnlock_update(asus);
> @@ -3844,6 +3975,7 @@ static int asus_wmi_add(struct platform_device *pdev)
>  
>  fail_wmi_handler:
>  	asus_wmi_backlight_exit(asus);
> +	asus_screenpad_exit(asus);
>  fail_backlight:
>  	asus_wmi_rfkill_exit(asus);
>  fail_rfkill:
> diff --git a/drivers/platform/x86/asus-wmi.h b/drivers/platform/x86/asus-wmi.h
> index a478ebfd34df..5fbdd0eafa02 100644
> --- a/drivers/platform/x86/asus-wmi.h
> +++ b/drivers/platform/x86/asus-wmi.h
> @@ -57,6 +57,7 @@ struct quirk_entry {
>  struct asus_wmi_driver {
>  	int			brightness;
>  	int			panel_power;
> +	int			screenpad_brightness;
>  	int			wlan_ctrl_by_user;
>  
>  	const char		*name;
> diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
> index 28234dc9fa6a..a2d94adb5c80 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -58,6 +58,10 @@
>  #define ASUS_WMI_DEVID_KBD_BACKLIGHT	0x00050021
>  #define ASUS_WMI_DEVID_LIGHT_SENSOR	0x00050022 /* ?? */
>  #define ASUS_WMI_DEVID_LIGHTBAR		0x00050025
> +/* This can only be used to disable the screen, not re-enable */
> +#define ASUS_WMI_DEVID_SCREENPAD_POWER	0x00050031
> +/* Writing a brightness re-enables the screen if disabled */
> +#define ASUS_WMI_DEVID_SCREENPAD_LIGHT	0x00050032
>  #define ASUS_WMI_DEVID_FAN_BOOST_MODE	0x00110018
>  #define ASUS_WMI_DEVID_THROTTLE_THERMAL_POLICY 0x00120075
>  
>