From: Hans de Goede <hdegoede@redhat.com>
To: Coiby Xu <coiby.xu@gmail.com>
Cc: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>,
Linus Walleij <linus.walleij@linaro.org>,
wang jun <availa@outlook.com>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
linux-kernel-mentees@lists.linuxfoundation.org,
Nehal Shah <Nehal-bakulchandra.Shah@amd.com>
Subject: Re: [Linux-kernel-mentees] Any other ways to debug GPIO interrupt controller (pinctrl-amd) for broken touchpads of a new laptop model?
Date: Tue, 6 Oct 2020 11:28:06 +0200 [thread overview]
Message-ID: <4f02cbdf-e1dd-b138-4975-118dd4f86089@redhat.com> (raw)
In-Reply-To: <69853d2b-239c-79d5-bf6f-7dc0eec65602@redhat.com>
Hi,
On 10/6/20 10:55 AM, Hans de Goede wrote:
> Hi,
>
> On 10/6/20 10:31 AM, Coiby Xu wrote:
>> On Tue, Oct 06, 2020 at 08:28:40AM +0200, Hans de Goede wrote:
>>> Hi,
>>>
>>> On 10/6/20 6:49 AM, Coiby Xu wrote:
>>>> Hi Hans and Linus,
>>>>
>>>> I've found the direct evidence proving the GPIO interrupt controller is
>>>> malfunctioning.
>>>>
>>>> I've found a way to let the GPIO chip trigger an interrupt by accident
>>>> when playing with the GPIO sysfs interface,
>>>>
>>>> - export pin130 which is used by the touchad
>>>> - set the direction to be "out"
>>>> - `echo 0 > value` will trigger the GPIO controller's parent irq and
>>>> "echo 1 > value" will make it stop firing
>>>>
>>>> (I'm not sure if this is yet another bug of the GPIO chip. Anyway I can
>>>> manually trigger an interrupt now.)
>>>>
>>>> I wrote a C program is to let GPIO controller quickly generate some
>>>> interrupts then disable the firing of interrupts by toggling pin#130's
>>>> value with an specified time interval, i.e., set the value to 0 first
>>>> and then after some time, re-set the value to 1. There is no interrupt
>>>> firing unless time internal > 120ms (~7Hz). This explains why we can
>>>> only see 7 interrupts for the GPIO controller's parent irq.
>>>
>>> That is a great find, well done.
>>>
>>>> My hypothesis is the GPIO doesn't have proper power setting so it stays
>>>> in an idle state or its clock frequency is too low by default thus not
>>>> quick enough to read interrupt input. Then pinctrl-amd must miss some
>>>> code to configure the chip and I need a hardware reference manual of this
>>>> GPIO chip (HID: AMDI0030) or reverse-engineer the driver for Windows
>>>> since I couldn't find a copy of reference manual online? What would you
>>>> suggest?
>>>
>>> This sounds like it might have something to do with the glitch filter.
>>> The code in pinctrl-amd.c to setup the trigger-type also configures
>>> the glitch filter, you could try changing that code to disable the
>>> glitch-filter. The defines for setting the glitch-filter bits to
>>> disabled are already there.
>>>
>>
>> Disabling the glitch filter works like a charm! Other enthusiastic
>> Linux users who have been troubled by this issue for months would
>> also feel great to know this small tweaking could bring their
>> touchpad back to life:) Thank you!
>
> That is good to hear, I'm glad that we have finally found a solution.
>
>> $ git diff
>> diff --git a/drivers/pinctrl/pinctrl-amd.c b/drivers/pinctrl/pinctrl-amd.c
>> index 9a760f5cd7ed..e786d779d6c8 100644
>> --- a/drivers/pinctrl/pinctrl-amd.c
>> +++ b/drivers/pinctrl/pinctrl-amd.c
>> @@ -463,7 +463,7 @@ static int amd_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>> 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;
>> + /** pin_reg |= DB_TYPE_PRESERVE_HIGH_GLITCH << DB_CNTRL_OFF; */
>> irq_set_handler_locked(d, handle_level_irq);
>> break;
>>
>> I will learn more about the glitch filter and the implementation of
>> pinctrl and see if I can disable glitch filter only for this touchpad.
>
> The glitch filter likely also has settings for how long a glitch
> lasts, which apparently goes all the way up to 120ms. If it would
> only delay reporting by say 0.1ms and consider any pulse longer
> then 0.1s not a glitch, then having it enabled would be fine.
>
> I don't think we want some sort of quirk here to only disable the
> glitch filter for some touchpads. One approach might be to simply
> disable it completely for level type irqs.
>
> What we really need here is some input from AMD engineers with how
> this is all supposed to work.
>
> E.g. maybe the glitch-filter is setup by the BIOS and we should not
> touch it all ?
>
> Or maybe instead of DB_TYPE_PRESERVE_HIGH_GLITCH low level interrupts
> should use DB_TYPE_PRESERVE_LOW_GLITCH ? Some docs for the hw
> would really help here ...
So I've been digging through the history of the pinctrl-amd.c driver
and once upon a time it used to set a default debounce time of
2.75 ms.
See the patch generated by doing:
git format-patch 8cf4345575a416e6856a6856ac6eaa31ad883126~..8cf4345575a416e6856a6856ac6eaa31ad883126
In a linux kernel checkout.
So it would be interesting to add a debugging printk to see
what the value of pin_reg & DB_TMR_OUT_MASK is for the troublesome
GPIO.
I guess that it might be all 1s (0xfffffffff) or some such which
might be a way to check that we should disable the glitch-filter
for this pin?
Regards,
Hans
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next prev parent reply other threads:[~2020-10-06 9:28 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 13:22 [Linux-kernel-mentees] Any other ways to debug GPIO interrupt controller (pinctrl-amd) for broken touchpads of a new laptop model? Coiby Xu
2020-10-01 20:57 ` Linus Walleij
2020-10-02 9:40 ` Hans de Goede
2020-10-02 12:42 ` Coiby Xu
2020-10-02 13:36 ` Hans de Goede
2020-10-02 14:51 ` Coiby Xu
2020-10-02 19:44 ` Hans de Goede
2020-10-02 22:45 ` Coiby Xu
2020-10-03 13:22 ` Hans de Goede
2020-10-03 23:03 ` Coiby Xu
2020-10-04 5:16 ` Coiby Xu
2020-10-06 4:49 ` Coiby Xu
2020-10-06 6:28 ` Hans de Goede
2020-10-06 8:31 ` Coiby Xu
2020-10-06 8:55 ` Hans de Goede
2020-10-06 9:28 ` Hans de Goede [this message]
2020-10-06 9:29 ` Hans de Goede
2020-10-08 16:32 ` Coiby Xu
2020-10-14 4:24 ` Coiby Xu
2020-10-14 11:34 ` Coiby Xu
2020-10-14 11:46 ` Hans de Goede
2020-10-15 3:27 ` Coiby Xu
2020-10-15 4:06 ` Coiby Xu
2020-10-26 22:54 ` Coiby Xu
2020-10-27 9:52 ` Andy Shevchenko
2020-10-30 4:58 ` Coiby Xu
2020-10-27 10:09 ` Hans de Goede
2020-10-27 15:13 ` Andy Shevchenko
2020-10-27 16:00 ` Hans de Goede
2020-10-27 16:09 ` Andy Shevchenko
2020-10-29 8:04 ` Mika Westerberg
2020-10-30 4:54 ` Coiby Xu
2020-11-02 19:06 ` Andy Shevchenko
2020-11-02 22:56 ` Coiby Xu
2020-11-03 0:05 ` Coiby Xu
2020-11-03 10:12 ` Hans de Goede
2020-11-03 10:49 ` Andy Shevchenko
2020-11-03 11:00 ` Hans de Goede
2020-10-08 16:26 ` Coiby Xu
2020-10-06 9:16 ` Linus Walleij
2020-10-08 16:40 ` Coiby Xu
2020-10-02 10:59 ` Coiby Xu
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