linux-kernel - Re: [PATCH v2 2/2] intel-hid: add alternative method to enable switches

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Date:   Fri, 04 Dec 2020 16:22:18 +0100
From:   Elia Devito <eliadevito@...il.com>
To:     Barnabás Pőcze <pobrn@...tonmail.com>
Cc:     Alex Hung <alex.hung@...onical.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] intel-hid: add alternative method to enable switches

Hi Barnabás

In data venerdì 4 dicembre 2020 00:45:10 CET, Barnabás Pőcze ha scritto:
> Hi
> 
> 2020. december 3., csütörtök 22:21 keltezéssel, Elia Devito írta:
> > [...]
> > diff --git a/drivers/platform/x86/intel-hid.c
> > b/drivers/platform/x86/intel-hid.c index 86261970bd8f..fed24d4f28b8
> > 100644
> > --- a/drivers/platform/x86/intel-hid.c
> > +++ b/drivers/platform/x86/intel-hid.c
> > @@ -15,6 +15,9 @@
> > 
> >  #include <linux/platform_device.h>
> >  #include <linux/suspend.h>
> > 
> > +/* When NOT in tablet mode, VGBS returns with the flag 0x40 */
> > +#define TABLET_MODE_FLAG 0x40
> 
> I think `BIT(6)` would be better (linux/bits.h).
> 
Okay,  I will change it

> > +
> > 
> >  MODULE_LICENSE("GPL");
> >  MODULE_AUTHOR("Alex Hung");
> > 
> > @@ -89,9 +92,26 @@ static const struct dmi_system_id button_array_table[]
> > = {> 
> >  	{ }
> >  
> >  };
> > 
> > [...]
> > +static void detect_tablet_mode(struct platform_device *device)
> 
> I believe `report_tablet_mode_state()` or something similar would be a more
> apt name.
Sound good,  I will rename it.

> > +{
> > +	struct intel_hid_priv *priv = dev_get_drvdata(&device->dev);
> > +	acpi_handle handle = ACPI_HANDLE(&device->dev);
> > +	unsigned long long vgbs;
> > +	int m;
> > +
> > +	if (!intel_hid_evaluate_method(handle, INTEL_HID_DSM_VGBS_FN, 
&vgbs))
> > +		return;
> > +
> > +	m = !(vgbs & TABLET_MODE_FLAG);
> > +	input_report_switch(priv->switches, SW_TABLET_MODE, m);
> > +	input_sync(priv->switches);
> > +}
> > +
> > 
> >  static void notify_handler(acpi_handle handle, u32 event, void *context)
> >  {
> >  
> >  	struct platform_device *device = context;
> > 
> > @@ -363,6 +415,13 @@ static void notify_handler(acpi_handle handle, u32
> > event, void *context)> 
> >  		if (event == 0xce)
> >  		
> >  			goto wakeup;
> > 
> > +		/*
> > +		 * Switch events will wake the device and report the 
new switch
> > +		 * position to the input subsystem.
> > +		 */
> > +		if (priv->switches && (event == 0xcc || event == 0xcd))
> > +			goto wakeup;
> > +
> > 
> >  		/* Wake up on 5-button array events only. */
> >  		if (event == 0xc0 || !priv->array)
> >  		
> >  			return;
> > 
> > @@ -374,6 +433,21 @@ static void notify_handler(acpi_handle handle, u32
> > event, void *context)> 
> >  wakeup:
> >  		pm_wakeup_hard_event(&device->dev);
> > 
> > +
> > +		if (priv->switches) {
> > +			if (event == 0xcc) {
> > +				input_report_switch(priv-
>switches, SW_TABLET_MODE, 1);
> > +				input_sync(priv->switches);
> > +				return;
> > +			}
> > +
> > +			if (event == 0xcd) {
> > +				input_report_switch(priv-
>switches, SW_TABLET_MODE, 0);
> > +				input_sync(priv->switches);
> > +				return;
> > +			}
> > +		}
> > +
> > 
> >  		return;
> >  	
> >  	}
> > 
> > @@ -398,6 +472,20 @@ static void notify_handler(acpi_handle handle, u32
> > event, void *context)> 
> >  		}
> >  	
> >  	}
> > 
> > +	if (priv->switches) {
> > +		if (event == 0xcc) {
> > +			input_report_switch(priv->switches, 
SW_TABLET_MODE, 1);
> > +			input_sync(priv->switches);
> > +			return;
> > +		}
> > +
> > +		if (event == 0xcd) {
> > +			input_report_switch(priv->switches, 
SW_TABLET_MODE, 0);
> > +			input_sync(priv->switches);
> > +			return;
> > +		}
> > +	}
> 
> Wouldn't be better to create a new function `bool
> report_tablet_mode_event()` which would basically contain the above `if` or
> better, a `switch`, and then you could use it here and in the wake-up path
> like the following:
> 
> ```
> if (report_tablet_mode_event(priv->switches, event))
>   return;
> ```
> (or similarly)
> 
Looks more clean, I will do.

> > +
> > 
> >  	/* 0xC0 is for HID events, other values are for 5 button array */
> >  	if (event != 0xc0) {
> >  	
> >  		if (!priv->array ||
> > 
> > @@ -485,6 +573,16 @@ static int intel_hid_probe(struct platform_device
> > *device)> 
> >  			pr_err("Failed to setup Intel 5 button array 
hotkeys\n");
> >  	
> >  	}
> > 
> > +	/* Setup switches for devices that we know VGBS return correctly 
*/
> > +	if (dmi_check_system(dmi_vgbs_allow_list)) {
> > +		dev_info(&device->dev, "platform supports switches\n");
> > +		err = intel_hid_switches_setup(device);
> > +		if (err)
> > +			pr_err("Failed to setup Intel HID 
switches\n");
> > +		else
> > +			detect_tablet_mode(device);
> > +	}
> > +
> > 
> >  	status = acpi_install_notify_handler(handle,
> >  	
> >  					     
ACPI_DEVICE_NOTIFY,
> >  					     notify_handler,
> > 
> > --
> > 2.28.0
> 
> Regards,
> Barnabás Pőcze

Thank you for the review

Regards
Elia