linux-kernel - Re: [PATCH v6] ACPI: skip IRQ override on AMD Zen platforms

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Message-ID: <8eef6593-ebaf-5b5a-b9b2-c93277d4afaa@amd.com>
Date:   Mon, 18 Jul 2022 10:39:21 -0500
From:   "Limonciello, Mario" <mario.limonciello@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Chuanhong Guo <gch981213@...il.com>
Cc:     ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Tighe Donnelly <tighe.donnelly@...tonmail.com>,
        Len Brown <lenb@...nel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6] ACPI: skip IRQ override on AMD Zen platforms

On 7/14/2022 13:35, Rafael J. Wysocki wrote:
> On Tue, Jul 12, 2022 at 4:01 AM Chuanhong Guo <gch981213@...il.com> wrote:
>>
>> IRQ override isn't needed on modern AMD Zen systems.
>> There's an active low keyboard IRQ on AMD Ryzen 6000 and it will stay
>> this way on newer platforms. This IRQ override breaks keyboards for
>> almost all Ryzen 6000 laptops currently on the market.
>>
>> Skip this IRQ override for all AMD Zen platforms because this IRQ
>> override is supposed to be a workaround for buggy ACPI DSDT and we can't
>> have a long list of all future AMD CPUs/Laptops in the kernel code.
>> If a device with buggy ACPI DSDT shows up, a separated list containing
>> just them should be created.
>>
>> Suggested-by: Mario Limonciello <mario.limonciello@....com>
>> Signed-off-by: Chuanhong Guo <gch981213@...il.com>
> 
> I need an ACK from Mario here.

Sure.  As he mentioned this polarity change is needed going forward.
So if we end up with a similar regression as the Baytrail attempt to 
make this generic and need to revert we'll need to find a different 
heuristic to make it generic on RMB and later.

Acked-by: Mario Limonciello <mario.limonciello@....com>

Here's some other tags to pick up too in the commit message.

Tested-by: XiaoYan Li <lxy.lixiaoyan@...il.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216118

> 
>> ---
>> Change sice v5: reworked
>>
>>   drivers/acpi/resource.c | 10 ++++++++++
>>   1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
>> index c2d494784425..510cdec375c4 100644
>> --- a/drivers/acpi/resource.c
>> +++ b/drivers/acpi/resource.c
>> @@ -416,6 +416,16 @@ static bool acpi_dev_irq_override(u32 gsi, u8 triggering, u8 polarity,
>>   {
>>          int i;
>>
>> +#ifdef CONFIG_X86
>> +       /*
>> +        * IRQ override isn't needed on modern AMD Zen systems and
>> +        * this override breaks active low IRQs on AMD Ryzen 6000 and
>> +        * newer systems. Skip it.
>> +        */
>> +       if (boot_cpu_has(X86_FEATURE_ZEN))
>> +               return false;
>> +#endif
>> +
>>          for (i = 0; i < ARRAY_SIZE(skip_override_table); i++) {
>>                  const struct irq_override_cmp *entry = &skip_override_table[i];
>>
>> --
>> 2.36.1
>>