linux-kernel - Re: [PATCH] platform/x86: amd-pmc: Increase the response register timeout

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Date:   Tue, 14 Sep 2021 12:34:43 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        Mario Limonciello <mario.limonciello@....com>
Cc:     stable@...nel.org, Julian Sikorski <belegdol@...il.com>,
        Mark Gross <mgross@...ux.intel.com>,
        "open list:AMD PMC DRIVER" <platform-driver-x86@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] platform/x86: amd-pmc: Increase the response register
 timeout

Hi,

On 9/14/21 10:38 AM, Shyam Sundar S K wrote:
> 
> 
> On 9/14/2021 7:31 AM, Mario Limonciello wrote:
>> There have been reports of approximately a 0.9%-1.7% failure rate in SMU
>> communication timeouts with s0i3 entry on some OEM designs.  Currently
>> the design in amd-pmc is to try every 100us for up to 20ms.
>>
>> However the GPU driver which also communicates with the SMU using a
>> mailbox register which the driver polls every 1us for up to 2000ms.
>> In the GPU driver this was increased by commit 055162645a40 ("drm/amd/pm:
>> increase time out value when sending msg to SMU")
>>
>> Increase the maximum timeout used by amd-pmc to 2000ms to match this
>> behavior.  This has been shown to improve the stability for machines
>> that randomly have failures.
>>
>> Cc: stable@...nel.org
>> Reported-by: Julian Sikorski <belegdol@...il.com>
>> BugLink: https://gitlab.freedesktop.org/drm/amd/-/issues/1629
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> ---
>>  drivers/platform/x86/amd-pmc.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/platform/x86/amd-pmc.c b/drivers/platform/x86/amd-pmc.c
>> index 3481479a2942..d6a7c896ac86 100644
>> --- a/drivers/platform/x86/amd-pmc.c
>> +++ b/drivers/platform/x86/amd-pmc.c
>> @@ -71,7 +71,7 @@
>>  #define AMD_CPU_ID_YC			0x14B5
>>  
>>  #define PMC_MSG_DELAY_MIN_US		100
>> -#define RESPONSE_REGISTER_LOOP_MAX	200
>> +#define RESPONSE_REGISTER_LOOP_MAX	20000
>>  
>>  #define SOC_SUBSYSTEM_IP_MAX	12
>>  #define DELAY_MIN_US		2000
>>
> 
> Looks good to me.
> 
> Acked-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

I've also added this to the fixes branch so that it will be included
when I send my next fixes for 5.15 pull-req to Linus.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans