Re: [PATCH 2/3] asus-wmi: Add dgpu disable method

[Luke Jones]

Thank you for the insightful feedback.

On Mon, Jul 5 2021 at 00:47:31 +0000, Barnabás Pőcze 
<pobrn@xxxxxxxxxxxxxx> wrote:
> Hi
>
> I have added a couple comments inline.
>
>
> 2021. július 5., hétfő 0:21 keltezéssel, Luke D. Jones írta:
>
> >  In Windows the ASUS Armory Crate progrm can enable or disable the
>                                         ^
> "program"
My "a" key is a little hard to press sometimes :(

> >  dGPU via a WMI call. This functions much the same as various Linux
> >  methods in software where the dGPU is removed from the device tree.
> >
> >  However the WMI call saves the state of dGPU enabled or not and this
>
> I think "[...] the WMI call saves whether the dGPU is enabled or not, 
> and [...]"
> might be better.
> Or "[...] the WMI call saves the state of the dGPU (enabled or not) 
> and [...]".
I've used the second option, thanks for pointing this out.

> >  then changes the dGPU visibility in Linux with no way for Linux
> >  users to re-enable it. We expose the WMI method so users can see
> >  and change the dGPU ACPI state.
> >
> >  Signed-off-by: Luke D. Jones <luke@xxxxxxxxxx>
> >  ---
> >   drivers/platform/x86/asus-wmi.c            | 98 
> > ++++++++++++++++++++++
> >   include/linux/platform_data/x86/asus-wmi.h |  3 +
> >   2 files changed, 101 insertions(+)
> >
> >  diff --git a/drivers/platform/x86/asus-wmi.c 
> > b/drivers/platform/x86/asus-wmi.c
> >  index 2468076d6cd8..8dc3f7ed021f 100644
> >  --- a/drivers/platform/x86/asus-wmi.c
> >  +++ b/drivers/platform/x86/asus-wmi.c
> >  @@ -210,6 +210,9 @@ struct asus_wmi {
> >   	u8 fan_boost_mode_mask;
> >   	u8 fan_boost_mode;
> >
> >  +	bool dgpu_disable_available;
> >  +	u8 dgpu_disable_mode;
> >  +
> >   	bool throttle_thermal_policy_available;
> >   	u8 throttle_thermal_policy_mode;
> >
> >  @@ -427,6 +430,93 @@ static void 
> > lid_flip_tablet_mode_get_state(struct asus_wmi *asus)
> >   	}
> >   }
> >
> >  +/* dGPU 
> > ********************************************************************/
> >  +static int dgpu_disable_check_present(struct asus_wmi *asus)
> >  +{
> >  +	u32 result;
> >  +	int err;
> >  +
> >  +	asus->dgpu_disable_available = false;
> >  +
> >  +	err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_DGPU, &result);
> >  +	if (err) {
> >  +		if (err == -ENODEV)
> >  +			return 0;
> >  +		return err;
> >  +	}
> >  +
> >  +	if (result & ASUS_WMI_DSTS_PRESENCE_BIT)
> >  +		asus->dgpu_disable_available = true;
> >  +		asus->dgpu_disable_mode = result & ASUS_WMI_DSTS_STATUS_BIT;
> >  +
>
> Aren't braces missing here?
Yep. Fixed.

> >  +	return 0;
> >  +}
> >  +
> >  +static int dgpu_disable_write(struct asus_wmi *asus)
> >  +{
> >  +	int err;
> >  +	u8 value;
> >  +	u32 retval;
> >  +
> >  +	value = asus->dgpu_disable_mode;
> >  +
> >  +	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_DGPU, value, &retval);
> >  +
> >  +	sysfs_notify(&asus->platform_device->dev.kobj, NULL,
> >  +			"dgpu_disable");
>
> A similar line with the exact same length in patch 3/3 is not broken 
> in two.
> And shouldn't the notification be sent if the operation succeeded?
Fixed. I moved the sysfs_notify down below the error returns.
> >  +
> >  +	if (err) {
> >  +		pr_warn("Failed to set dgpu disable: %d\n", err);
> >  +		return err;
> >  +	}
> >  +
> >  +	if (retval > 1 || retval < 0) {
> >  +		pr_warn("Failed to set dgpu disable (retval): 0x%x\n",
> >  +			retval);
> >  +		return -EIO;
> >  +	}
> >  +
> >  +	return 0;
> >  +}
> >  +
> >  +static ssize_t dgpu_disable_show(struct device *dev,
> >  +				   struct device_attribute *attr, char *buf)
> >  +{
> >  +	struct asus_wmi *asus = dev_get_drvdata(dev);
> >  +	u8 mode = asus->dgpu_disable_mode;
> >  +
> >  +	return scnprintf(buf, PAGE_SIZE, "%d\n", mode);
>
> You could use `sysfs_emit()`.
Thanks. Many things like this I'm actually unaware of. Most of these 
patches are done by reading existing code.

> >  +}
> >  +
> >  +static ssize_t dgpu_disable_store(struct device *dev,
> >  +				    struct device_attribute *attr,
> >  +				    const char *buf, size_t count)
> >  +{
> >  +	int result;
> >  +	u8 disable;
> >  +	struct asus_wmi *asus = dev_get_drvdata(dev);
> >  +
> >  +	result = kstrtou8(buf, 10, &disable);
>
> You could use `kstrtobool()`. I think that would be better since it 
> accepts
> 'y', 'n', etc. in addition to 0 and 1.
Thanks! Wasn't aware of that. And since the setting for all 3 patches 
can only ever be 0/1 I've changed to use a bool instead of u8

> >  +	if (result < 0)
> >  +		return result;
> >  +
> >  +	if (disable > 1 || disable < 0)
> >  +		return -EINVAL;
> >  +
> >  +	asus->dgpu_disable_mode = disable;
> >  +	/*
> >  +	 * The ACPI call used does not save the mode unless the call is 
> > run twice.
> >  +	 * Once to disable, then once to check status and save - this is 
> > two code
> >  +	 * paths in the method in the ACPI dumps.
> >  +	*/
> >  +	dgpu_disable_write(asus);
> >  +	dgpu_disable_write(asus);
>
> Is there any reason the potential error codes are not returned?
No I've fixed now. Guess I missed it.

> >  +
> >  +	return count;
> >  +}
> >  +
> >  +static DEVICE_ATTR_RW(dgpu_disable);
> >  +
> >   /* Battery 
> > ********************************************************************/
> >
> >   /* The battery maximum charging percentage */
> >  @@ -2412,6 +2502,7 @@ static struct attribute 
> > *platform_attributes[] = {
> >   	&dev_attr_camera.attr,
> >   	&dev_attr_cardr.attr,
> >   	&dev_attr_touchpad.attr,
> >  +	&dev_attr_dgpu_disable.attr,
> >   	&dev_attr_lid_resume.attr,
> >   	&dev_attr_als_enable.attr,
> >   	&dev_attr_fan_boost_mode.attr,
> >  @@ -2438,6 +2529,8 @@ static umode_t asus_sysfs_is_visible(struct 
> > kobject *kobj,
> >   		devid = ASUS_WMI_DEVID_LID_RESUME;
> >   	else if (attr == &dev_attr_als_enable.attr)
> >   		devid = ASUS_WMI_DEVID_ALS_ENABLE;
> >  +	else if (attr == &dev_attr_dgpu_disable.attr)
> >  +		ok = asus->dgpu_disable_available;
> >   	else if (attr == &dev_attr_fan_boost_mode.attr)
> >   		ok = asus->fan_boost_mode_available;
> >   	else if (attr == &dev_attr_throttle_thermal_policy.attr)
> >  @@ -2699,6 +2792,10 @@ static int asus_wmi_add(struct 
> > platform_device *pdev)
> >   	if (err)
> >   		goto fail_platform;
> >
> >  +	err = dgpu_disable_check_present(asus);
> >  +	if (err)
> >  +		goto fail_dgpu_disable;
> >  +
>
> Should this really be considered a "fatal" error?
I was modelling this on fail_fan_boost_mode and 
fail_throttle_thermal_policy since a laptop can't have both of those 
which indicates that a failed one is fine, it seemed appropriate to 
follow the same behaviour here

> >   	err = fan_boost_mode_check_present(asus);
> >   	if (err)
> >   		goto fail_fan_boost_mode;
> >  @@ -2799,6 +2896,7 @@ static int asus_wmi_add(struct 
> > platform_device *pdev)
> >   fail_sysfs:
> >   fail_throttle_thermal_policy:
> >   fail_fan_boost_mode:
> >  +fail_dgpu_disable:
> >   fail_platform:
> >   fail_panel_od:
> >   	kfree(asus);
> >  diff --git a/include/linux/platform_data/x86/asus-wmi.h 
> > b/include/linux/platform_data/x86/asus-wmi.h
> >  index 428aea701c7b..a528f9d0e4b7 100644
> >  --- a/include/linux/platform_data/x86/asus-wmi.h
> >  +++ b/include/linux/platform_data/x86/asus-wmi.h
> >  @@ -90,6 +90,9 @@
> >   /* Keyboard dock */
> >   #define ASUS_WMI_DEVID_KBD_DOCK		0x00120063
> >
> >  +/* dgpu on/off */
> >  +#define ASUS_WMI_DEVID_DGPU		0x00090020
> >  +
> >   /* DSTS masks */
> >   #define ASUS_WMI_DSTS_STATUS_BIT	0x00000001
> >   #define ASUS_WMI_DSTS_UNKNOWN_BIT	0x00000002
> >  --
> >  2.31.1
>
>
> Regards,
> Barnabás Pőcze

Many thanks for your feedback again.
Luke.