linux-kernel - Re: [PATCH v3 4/4] pinctrl: amd: remove debounce filter setting in IRQ type setting

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Date:   Tue, 10 Nov 2020 16:26:33 +0800
From:   Coiby Xu <coiby.xu@...il.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        linux-gpio@...r.kernel.org,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        stable@...r.kernel.org, open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 4/4] pinctrl: amd: remove debounce filter setting in
 IRQ type setting

On Mon, Nov 09, 2020 at 02:52:17PM +0100, Hans de Goede wrote:
>Hi,
>
>On 11/6/20 12:19 AM, Coiby Xu wrote:
>> Debounce filter setting should be independent from IRQ type setting
>> because according to the ACPI specs, there are separate arguments for
>> specifying debounce timeout and IRQ type in GpioIo() and GpioInt().
>>
>> This will fix broken touchpads for laptops whose BIOS set the debounce
>> timeout to a relatively large value. For example, the BIOS of Lenovo
>> Legion-5 AMD gaming laptops including 15ARH05 (R7000) and R7000P set
>> the debounce timeout to 124.8ms. This led to the kernel receiving only
>> ~7 HID reports per second from the Synaptics touchpad
>> (MSFT0001:00 06CB:7F28). Existing touchpads like [1][2] are not troubled
>> by this bug because the debounce timeout has been set to 0 by the BIOS
>> before enabling the debounce filter in setting IRQ type.
>>
>> [1] https://github.com/Syniurge/i2c-amd-mp2/issues/11#issuecomment-721331582
>> [2] https://forum.manjaro.org/t/random-short-touchpad-freezes/30832/28
>>
>> Cc: Hans de Goede <hdegoede@...hat.com>
>> Cc: Andy Shevchenko <andy.shevchenko@...il.com>
>> Cc: Benjamin Tissoires <benjamin.tissoires@...hat.com>
>> Cc: stable@...r.kernel.org
>> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>> BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1887190
>> Link: https://lore.kernel.org/linux-gpio/CAHp75VcwiGREBUJ0A06EEw-SyabqYsp%2Bdqs2DpSrhaY-2GVdAA%40mail.gmail.com/
>> Signed-off-by: Coiby Xu <coiby.xu@...il.com>
>
>I'm not entirely sure about this patch. This is consistent with how we
>already stopped touching the debounce timeout setting during init, so
>that speaks in favor of this change.
>
>Still I'm worried a bit that this might have undesirable side effects.
>
Now I can only confirm this patch won't affect the mentioned touchpads.
I'll see if other distributions like Manjaro are willing to test it
through the unstable channel.

>I guess this should be landed together with Andy's series to apply
>the debounce setting from the ACPI GPIO resources.

Thank you for the reminding! You are right, Andy's patch
"gpiolib: acpi: Take into account debounce settings" is needed to
fix this kind of touchpad issues. Since that patch hasn't been
merged, is there a way to refer to it in the commit message?
>
>Regards,
>
>Hans
>
>
>
>
>> ---
>>  drivers/pinctrl/pinctrl-amd.c | 7 -------
>>  1 file changed, 7 deletions(-)
>>
>> diff --git a/drivers/pinctrl/pinctrl-amd.c b/drivers/pinctrl/pinctrl-amd.c
>> index e9b761c2b77a..2d4acf21117c 100644
>> --- a/drivers/pinctrl/pinctrl-amd.c
>> +++ b/drivers/pinctrl/pinctrl-amd.c
>> @@ -468,7 +468,6 @@ static int amd_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>>  		pin_reg &= ~BIT(LEVEL_TRIG_OFF);
>>  		pin_reg &= ~(ACTIVE_LEVEL_MASK << ACTIVE_LEVEL_OFF);
>>  		pin_reg |= ACTIVE_HIGH << ACTIVE_LEVEL_OFF;
>> -		pin_reg |= DB_TYPE_REMOVE_GLITCH << DB_CNTRL_OFF;
>>  		irq_set_handler_locked(d, handle_edge_irq);
>>  		break;
>>
>> @@ -476,7 +475,6 @@ static int amd_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>>  		pin_reg &= ~BIT(LEVEL_TRIG_OFF);
>>  		pin_reg &= ~(ACTIVE_LEVEL_MASK << ACTIVE_LEVEL_OFF);
>>  		pin_reg |= ACTIVE_LOW << ACTIVE_LEVEL_OFF;
>> -		pin_reg |= DB_TYPE_REMOVE_GLITCH << DB_CNTRL_OFF;
>>  		irq_set_handler_locked(d, handle_edge_irq);
>>  		break;
>>
>> @@ -484,7 +482,6 @@ static int amd_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>>  		pin_reg &= ~BIT(LEVEL_TRIG_OFF);
>>  		pin_reg &= ~(ACTIVE_LEVEL_MASK << ACTIVE_LEVEL_OFF);
>>  		pin_reg |= BOTH_EADGE << ACTIVE_LEVEL_OFF;
>> -		pin_reg |= DB_TYPE_REMOVE_GLITCH << DB_CNTRL_OFF;
>>  		irq_set_handler_locked(d, handle_edge_irq);
>>  		break;
>>
>> @@ -492,8 +489,6 @@ static int amd_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>>  		pin_reg |= LEVEL_TRIGGER << LEVEL_TRIG_OFF;
>>  		pin_reg &= ~(ACTIVE_LEVEL_MASK << ACTIVE_LEVEL_OFF);
>>  		pin_reg |= ACTIVE_HIGH << ACTIVE_LEVEL_OFF;
>> -		pin_reg &= ~(DB_CNTRl_MASK << DB_CNTRL_OFF);
>> -		pin_reg |= DB_TYPE_PRESERVE_LOW_GLITCH << DB_CNTRL_OFF;
>>  		irq_set_handler_locked(d, handle_level_irq);
>>  		break;
>>
>> @@ -501,8 +496,6 @@ static int amd_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>>  		pin_reg |= LEVEL_TRIGGER << LEVEL_TRIG_OFF;
>>  		pin_reg &= ~(ACTIVE_LEVEL_MASK << ACTIVE_LEVEL_OFF);
>>  		pin_reg |= ACTIVE_LOW << ACTIVE_LEVEL_OFF;
>> -		pin_reg &= ~(DB_CNTRl_MASK << DB_CNTRL_OFF);
>> -		pin_reg |= DB_TYPE_PRESERVE_HIGH_GLITCH << DB_CNTRL_OFF;
>>  		irq_set_handler_locked(d, handle_level_irq);
>>  		break;
>>
>>
>

--
Best regards,
Coiby