linux-kernel - Re: [PATCH 1/3] asus-wmi: Add panel overdrive functionality

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Date:   Tue, 6 Jul 2021 12:07:00 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Luke D. Jones" <luke@...nes.dev>
Cc:     corentin.chary@...il.com, mgross@...ux.intel.com,
        jdelvare@...e.com, linux@...ck-us.net,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] asus-wmi: Add panel overdrive functionality

Hi,

Thank you for your patches, I've added several remarks inline (below);

On 7/5/21 12:21 AM, Luke D. Jones wrote:
> Some ASUS ROG laptops have the ability to drive the display panel
> a a higher rate to eliminate or reduce ghosting.
> 
> Signed-off-by: Luke D. Jones <luke@...nes.dev>
> ---
>  drivers/platform/x86/asus-wmi.c            | 92 ++++++++++++++++++++++
>  include/linux/platform_data/x86/asus-wmi.h |  1 +
>  2 files changed, 93 insertions(+)
> 
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index ebaeb7bb80f5..2468076d6cd8 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -216,6 +216,9 @@ struct asus_wmi {
>  	// The RSOC controls the maximum charging percentage.
>  	bool battery_rsoc_available;
>  
> +	bool panel_overdrive_available;
> +	u8 panel_overdrive;
> +
>  	struct hotplug_slot hotplug_slot;
>  	struct mutex hotplug_lock;
>  	struct mutex wmi_lock;
> @@ -1221,6 +1224,87 @@ static int asus_wmi_rfkill_init(struct asus_wmi *asus)
>  	return result;
>  }
>  
> +/* Panel Overdrive ************************************************************/
> +static int panel_od_check_present(struct asus_wmi *asus)
> +{
> +	u32 result;
> +	int err;
> +
> +	asus->panel_overdrive_available = false;
> +
> +	err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_PANEL_OD, &result);
> +	if (err) {
> +		if (err == -ENODEV)
> +			return 0;
> +		return err;
> +	}
> +
> +	if (result & ASUS_WMI_DSTS_PRESENCE_BIT)
> +		asus->panel_overdrive_available = true;
> +		asus->panel_overdrive = result & ASUS_WMI_DSTS_STATUS_BIT;

As the kernel-test-robot pointed out this if is missing { } around the
2 statements which should only be executed if the condition is true.

> +
> +	return 0;
> +}
> +
> +static int panel_od_write(struct asus_wmi *asus)
> +{
> +	int err;
> +	u8 value;
> +	u32 retval;
> +
> +	value = asus->panel_overdrive;
> +
> +	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_PANEL_OD, value, &retval);
> +
> +	sysfs_notify(&asus->platform_device->dev.kobj, NULL,
> +			"panel_od");

Please make this a single line.

> +
> +	if (err) {
> +		pr_warn("Failed to set panel overdrive: %d\n", err);
> +		return err;
> +	}
> +
> +	if (retval > 1 || retval < 0) {
> +		pr_warn("Failed to set panel overdrive (retval): 0x%x\n",
> +			retval);

Please make this a single line too.

> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +static ssize_t panel_od_show(struct device *dev,
> +				   struct device_attribute *attr, char *buf)
> +{
> +	struct asus_wmi *asus = dev_get_drvdata(dev);
> +	u8 mode = asus->panel_overdrive;
> +
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", mode);
> +}
> +
> +static ssize_t panel_od_store(struct device *dev,
> +				    struct device_attribute *attr,
> +				    const char *buf, size_t count)
> +{
> +	int result;
> +	u8 overdrive;
> +	struct asus_wmi *asus = dev_get_drvdata(dev);
> +
> +	result = kstrtou8(buf, 10, &overdrive);
> +	if (result < 0)
> +		return result;
> +
> +	if (overdrive > 1 || overdrive < 0)

An u8 can never be < 0, so please drop that check
(it will likely trigger compiler warnings in some cases).

> +		return -EINVAL;
> +
> +	asus->panel_overdrive = overdrive;
> +	panel_od_write(asus);
> +
> +	return count;
> +}
> +
> +static DEVICE_ATTR_RW(panel_od);
> +
>  /* Quirks *********************************************************************/
>  
>  static void asus_wmi_set_xusb2pr(struct asus_wmi *asus)
> @@ -2332,6 +2416,7 @@ static struct attribute *platform_attributes[] = {
>  	&dev_attr_als_enable.attr,
>  	&dev_attr_fan_boost_mode.attr,
>  	&dev_attr_throttle_thermal_policy.attr,
> +	&dev_attr_panel_od.attr,
>  	NULL
>  };
>  
> @@ -2357,6 +2442,8 @@ static umode_t asus_sysfs_is_visible(struct kobject *kobj,
>  		ok = asus->fan_boost_mode_available;
>  	else if (attr == &dev_attr_throttle_thermal_policy.attr)
>  		ok = asus->throttle_thermal_policy_available;
> +	else if (attr == &dev_attr_panel_od.attr)
> +		ok = asus->panel_overdrive_available;
>  
>  	if (devid != -1)
>  		ok = !(asus_wmi_get_devstate_simple(asus, devid) < 0);
> @@ -2622,6 +2709,10 @@ static int asus_wmi_add(struct platform_device *pdev)
>  	else
>  		throttle_thermal_policy_set_default(asus);
>  
> +	err = panel_od_check_present(asus);
> +	if (err)
> +		goto fail_panel_od;
> +
>  	err = asus_wmi_sysfs_init(asus->platform_device);
>  	if (err)
>  		goto fail_sysfs;
> @@ -2709,6 +2800,7 @@ static int asus_wmi_add(struct platform_device *pdev)
>  fail_throttle_thermal_policy:
>  fail_fan_boost_mode:
>  fail_platform:
> +fail_panel_od:
>  	kfree(asus);
>  	return err;
>  }
> diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
> index 2f274cf52805..428aea701c7b 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -61,6 +61,7 @@
>  #define ASUS_WMI_DEVID_THROTTLE_THERMAL_POLICY 0x00120075
>  
>  /* Misc */
> +#define ASUS_WMI_DEVID_PANEL_OD		0x00050019
>  #define ASUS_WMI_DEVID_CAMERA		0x00060013
>  #define ASUS_WMI_DEVID_LID_FLIP		0x00060062
>  
> 

Otherwise this looks good to me,

Regards,

Hans