linux-kernel - Re: [PATCH v2] platform/x86: intel_int0002_vgpio: Only bind to the INT0002 dev when using s2idle

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Date:   Wed, 15 Apr 2020 11:48:20 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        Maxim Mikityanskiy <maxtram95@...il.com>,
        "5 . 3+" <stable@...r.kernel.org>
Subject: Re: [PATCH v2] platform/x86: intel_int0002_vgpio: Only bind to the
 INT0002 dev when using s2idle

Hi,

On 4/15/20 11:45 AM, Rafael J. Wysocki wrote:
> On Tuesday, April 14, 2020 3:19:53 PM CEST Hans de Goede wrote:
>> Commit 871f1f2bcb01 ("platform/x86: intel_int0002_vgpio: Only implement
>> irq_set_wake on Bay Trail") stopped passing irq_set_wake requests on to
>> the parents IRQ because this was breaking suspend (causing immediate
>> wakeups) on an Asus E202SA.
>>
>> This workaround for this issue is mostly fine, on most Cherry Trail
>> devices where we need the INT0002 device for wakeups by e.g. USB kbds,
>> the parent IRQ is shared with the ACPI SCI and that is marked as wakeup
>> anyways.
>>
>> But not on all devices, specifically on a Medion Akoya E1239T there is
>> no SCI at all, and because the irq_set_wake request is not passed on to
>> the parent IRQ, wake up by the builtin USB kbd does not work here.
>>
>> So the workaround for the Asus E202SA immediate wake problem is causing
>> problems elsewhere; and in hindsight it is not the correct fix,
>> the Asus E202SA uses Airmont CPU cores, but this does not mean it is a
>> Cherry Trail based device, Brasswell uses Airmont CPU cores too and this
>> actually is a Braswell device.
>>
>> Most (all?) Braswell devices use classic S3 mode suspend rather then
>> s2idle suspend and in this case directly dealing with PME events as
>> the INT0002 driver does likely is not the best idea, so that this is
>> causing issues is not surprising.
>>
>> Replace the workaround of not passing irq_set_wake requests on to the
>> parents IRQ, by not binding to the INT0002 device when s2idle is not used.
>> This fixes USB kbd wakeups not working on some Cherry Trail devices,
>> while still avoiding mucking with the wakeup flags on the Asus E202SA
>> (and other Brasswell devices).
>>
>> Cc: Maxim Mikityanskiy <maxtram95@...il.com>
>> Cc: 5.3+ <stable@...r.kernel.org> # 5.3+
>> Fixes: 871f1f2bcb01 ("platform/x86: intel_int0002_vgpio: Only implement irq_set_wake on Bay Trail")
>> Tested-by: Maxim Mikityanskiy <maxtram95@...il.com>
>> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
>> ---
>> Changes in v2:
>> - Rebase on top of 5.7-rc1
>> ---
>>   drivers/platform/x86/intel_int0002_vgpio.c | 18 +++++-------------
>>   1 file changed, 5 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/platform/x86/intel_int0002_vgpio.c b/drivers/platform/x86/intel_int0002_vgpio.c
>> index 289c6655d425..30806046b664 100644
>> --- a/drivers/platform/x86/intel_int0002_vgpio.c
>> +++ b/drivers/platform/x86/intel_int0002_vgpio.c
>> @@ -143,21 +143,9 @@ static struct irq_chip int0002_byt_irqchip = {
>>   	.irq_set_wake		= int0002_irq_set_wake,
>>   };
>>   
>> -static struct irq_chip int0002_cht_irqchip = {
>> -	.name			= DRV_NAME,
>> -	.irq_ack		= int0002_irq_ack,
>> -	.irq_mask		= int0002_irq_mask,
>> -	.irq_unmask		= int0002_irq_unmask,
>> -	/*
>> -	 * No set_wake, on CHT the IRQ is typically shared with the ACPI SCI
>> -	 * and we don't want to mess with the ACPI SCI irq settings.
>> -	 */
>> -	.flags			= IRQCHIP_SKIP_SET_WAKE,
>> -};
>> -
>>   static const struct x86_cpu_id int0002_cpu_ids[] = {
>>   	X86_MATCH_INTEL_FAM6_MODEL(ATOM_SILVERMONT,	&int0002_byt_irqchip),
>> -	X86_MATCH_INTEL_FAM6_MODEL(ATOM_AIRMONT,	&int0002_cht_irqchip),
>> +	X86_MATCH_INTEL_FAM6_MODEL(ATOM_AIRMONT,	&int0002_byt_irqchip),
>>   	{}
>>   };
>>   
>> @@ -181,6 +169,10 @@ static int int0002_probe(struct platform_device *pdev)
>>   	if (!cpu_id)
>>   		return -ENODEV;
>>   
>> +	/* We only need to directly deal with PMEs when using s2idle */
>> +	if (!pm_suspend_default_s2idle())
>> +		return -ENODEV;
>> +
> 
> What if the system supports s2idle which is not the default suspend option
> and then it is selected by user space (overriding the default)?

This driver only binds (the cpuid check still visible above) on Bay Trail
and Cherry Trail/Brasswell systems. AFAIK those never support both modes,
the laptop variants of these SoCs always use S3 and the tablet versions
always use s2idle.

Regards,

Hans