Re: [PATCH] platform/x86: hp-wmi: Disable tablet-mode reporting by default

[mark gross <mgross@linux.intel.com>]

On Wed, Jan 20, 2021 at 01:49:41PM +0100, Hans de Goede wrote:
> Recently userspace has started making more use of SW_TABLET_MODE
> (when an input-dev reports this).
> 
> Specifically recent GNOME3 versions will:
> 
> 1.  When SW_TABLET_MODE is reported and is reporting 0:
> 1.1 Disable accelerometer-based screen auto-rotation
> 1.2 Disable automatically showing the on-screen keyboard when a
>     text-input field is focussed
> 
> 2.  When SW_TABLET_MODE is reported and is reporting 1:
> 2.1 Ignore input-events from the builtin keyboard and touchpad
>     (this is for 360° hinges style 2-in-1s where the keyboard and
>      touchpads are accessible on the back of the tablet when folded
>      into tablet-mode)
> 
> This means that claiming to support SW_TABLET_MODE when it does not
> actually work / reports correct values has bad side-effects.
did you mean "reports incorrect values"?

> 
> The check in the hp-wmi code which is used to decide if the input-dev
> should claim SW_TABLET_MODE support, only checks if the
> HPWMI_HARDWARE_QUERY is supported. It does *not* check if the hardware
> actually is capable of reporting SW_TABLET_MODE.
> 
> This leads to the hp-wmi input-dev claming SW_TABLET_MODE support,
> while in reality it will always report 0 as SW_TABLET_MODE value.
> This has been seen on a "HP ENVY x360 Convertible 15-cp0xxx" and
> this likely is the case on a whole lot of other HP models.
> 
> This problem causes both auto-rotation and on-screen keyboard
> support to not work on affected x360 models.
> 
> There is no easy fix for this, but since userspace expects
> SW_TABLET_MODE reporting to be reliable when advertised it is
> better to not claim/report SW_TABLET_MODE support at all, then
                                                            than
> to claim to support it while it does not work.
> 
> To avoid the mentioned problems, add a new enable_tablet_mode_sw
> module-parameter which defaults to false.
> 
> Note I've made this an int using the standard -1=auto, 0=off, 1=on
> tripplet, with the hope that in the future we can come up with a
> better way to detect SW_TABLET_MODE support. ATM the default
> auto option just does the same as off.
> 
> BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1918255
> Cc: Stefan Brüns <stefan.bruens@rwth-aachen.de>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/platform/x86/hp-wmi.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/platform/x86/hp-wmi.c b/drivers/platform/x86/hp-wmi.c
> index 18bf8aeb5f87..ff028587cd21 100644
> --- a/drivers/platform/x86/hp-wmi.c
> +++ b/drivers/platform/x86/hp-wmi.c
> @@ -32,6 +32,10 @@ MODULE_LICENSE("GPL");
>  MODULE_ALIAS("wmi:95F24279-4D7B-4334-9387-ACCDC67EF61C");
>  MODULE_ALIAS("wmi:5FB7F034-2C63-45e9-BE91-3D44E2C707E4");
>  
> +static int enable_tablet_mode_sw = -1;
So busted HW gets the default while working HW will need to add a boot time
parameter.  If there are no working tablet_mode devices I guess its ok but, if
I had a working platform I'd be a little miffed at the choice to make my life
harder (by forcing me to add a enable_tablet_mode_sw=1 to my kernel
command line) while making life easier for those with busted hardware.

I'm not saying change it but, it should be considered.

--mark


> +module_param(enable_tablet_mode_sw, int, 0444);
> +MODULE_PARM_DESC(enable_tablet_mode_sw, "Enable SW_TABLET_MODE reporting (-1=auto, 0=no, 1=yes)");
> +
>  #define HPWMI_EVENT_GUID "95F24279-4D7B-4334-9387-ACCDC67EF61C"
>  #define HPWMI_BIOS_GUID "5FB7F034-2C63-45e9-BE91-3D44E2C707E4"
>  
> @@ -654,10 +658,12 @@ static int __init hp_wmi_input_setup(void)
>  	}
>  
>  	/* Tablet mode */
> -	val = hp_wmi_hw_state(HPWMI_TABLET_MASK);
> -	if (!(val < 0)) {
> -		__set_bit(SW_TABLET_MODE, hp_wmi_input_dev->swbit);
> -		input_report_switch(hp_wmi_input_dev, SW_TABLET_MODE, val);
> +	if (enable_tablet_mode_sw > 0) {
> +		val = hp_wmi_hw_state(HPWMI_TABLET_MASK);
> +		if (!(val < 0)) {
> +			__set_bit(SW_TABLET_MODE, hp_wmi_input_dev->swbit);
> +			input_report_switch(hp_wmi_input_dev, SW_TABLET_MODE, val);
> +		}
>  	}
>  
>  	err = sparse_keymap_setup(hp_wmi_input_dev, hp_wmi_keymap, NULL);
> -- 
> 2.28.0
>