Date:   Tue, 5 May 2020 11:05:31 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Mario.Limonciello@...l.com, dvhart@...radead.org,
        andy@...radead.org
Cc:     linux-acpi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] platform/x86: intel-vbtn: Also handle tablet-mode
 switch on "Detachable" and "Portable" chassis-types

Hi,

On 5/4/20 5:37 PM, Mario.Limonciello@...l.com wrote:
> 
> 
>> -----Original Message-----
>> From: Hans de Goede <hdegoede@...hat.com>
>> Sent: Saturday, May 2, 2020 1:30 PM
>> To: Darren Hart; Andy Shevchenko; Limonciello, Mario
>> Cc: Hans de Goede; linux-acpi@...r.kernel.org; platform-driver-
>> x86@...r.kernel.org; linux-kernel@...r.kernel.org
>> Subject: [PATCH 4/5] platform/x86: intel-vbtn: Also handle tablet-mode switch
>> on "Detachable" and "Portable" chassis-types
>>
>>
>> [EXTERNAL EMAIL]
>>
>> Commit de9647efeaa9 ("platform/x86: intel-vbtn: Only activate tablet mode
>> switch on 2-in-1's") added a DMI chassis-type check to avoid accidentally
>> reporting SW_TABLET_MODE = 1 to userspace on laptops.
>>
>> Some devices with a detachable keyboard and using the intel-vbnt (INT33D6)
>> interface to report if they are in tablet mode (keyboard detached) or not,
>> report 32 / "Detachable" as chassis-type, e.g. the HP Pavilion X2 series.
>>
>> Other devices with a detachable keyboard and using the intel-vbnt (INT33D6)
>> interface to report SW_TABLET_MODE, report 8 / "Portable" as chassis-type.
>> The Dell Venue 11 Pro 7130 is an example of this.
>>
>> Extend the DMI chassis-type check to also accept Portables and Detachables
>> so that the intel-vbtn driver will report SW_TABLET_MODE on these devices.
>>
>> Note the chassis-type check was originally added to avoid a false-positive
>> tablet-mode report on the Dell XPS 9360 laptop. To the best of my knowledge
>> that laptop is using a chassis-type of 9 / "Laptop", so after this commit
>> we still ignore the tablet-switch for that chassis-type.
> 
> Yes that's correct.
> 
>>
>> Fixes: de9647efeaa9 ("platform/x86: intel-vbtn: Only activate tablet mode
>> switch on 2-in-1's")
>> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
>> ---
>> Looking at the Microsoft Windows documentation for tablet-mode reporting:
>> https://docs.microsoft.com/en-us/windows-hardware/drivers/gpiobtn/button-
>> implementation
>>
>> Then the presence of a tablet-mode switch is indicated by the presence
>> of a PNP0C60 compatible ACPI devices. There are 2 ways in which this device
>> can report the tablet-mode. 1. Directly providing a GpioInt resource inside
>> the PNP0C60 device, 2. Through injecting events from a Windows driver.
>>
>> It seems that the intel-vbtn / the INT33D6 ACPI device is the ACPI side
>> of Intel's generic solution for the case where the tablet-mode comes from
>> the embedded-controller and needs to be "injected".
>>
>> This all suggests that it might be better to replace the chassis-type
>> check with a acpi_dev_present("PNP0C60", NULL, -1) check.
>>
>> Mario, can you provide an acpidump and alsa-info.sh output for the
>> Dell XPS 9360, so that I can check if that might help with the issue
>> there, and thus is a potential candidate to replace the chassis-type
>> check?
> 
> Unfortunately with WFH right now, I don't have access to a XPS 9630 to
> double check the patch series.
> 
> However I do agree this should be a good approach.

Ok, so lets stick with the chassis-type check (as amended by this patch)
for now then. Then once you are able to go to your office again, we
can examine the acpi_dev_present("PNP0C60", NULL, -1) alternative.

> Reviewed-by: Mario Limonciello <Mario.limonciello@...l.com>

Thank you.

Regards,

Hans




>> ---
>>   drivers/platform/x86/intel-vbtn.c | 12 +++++++++++-
>>   1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/platform/x86/intel-vbtn.c b/drivers/platform/x86/intel-
>> vbtn.c
>> index 500fae82e12c..4921fc15dc6c 100644
>> --- a/drivers/platform/x86/intel-vbtn.c
>> +++ b/drivers/platform/x86/intel-vbtn.c
>> @@ -158,12 +158,22 @@ static void detect_tablet_mode(struct platform_device
>> *device)
>>   static bool intel_vbtn_has_switches(acpi_handle handle)
>>   {
>>   	const char *chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
>> +	unsigned long chassis_type_int;
>>   	unsigned long long vgbs;
>>   	acpi_status status;
>>
>> -	if (!(chassis_type && strcmp(chassis_type, "31") == 0))
>> +	if (kstrtoul(chassis_type, 10, &chassis_type_int))
>>   		return false;
>>
>> +	switch (chassis_type_int) {
>> +	case  8: /* Portable */
>> +	case 31: /* Convertible */
>> +	case 32: /* Detachable */
>> +		break;
>> +	default:
>> +		return false;
>> +	}
>> +
>>   	status = acpi_evaluate_integer(handle, "VGBS", NULL, &vgbs);
>>   	return ACPI_SUCCESS(status);
>>   }
>> --
>> 2.26.0
> 

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