linux-kernel - Re: [PATCH] platform/x86/amd: pmc: Add a workaround for an s0i3 issue on Cezanne

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Message-ID: <22d62cb7-17f4-c8d2-40fa-987bb2a4a0fa@redhat.com>
Date:   Thu, 17 Nov 2022 17:09:04 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Limonciello, Mario" <Mario.Limonciello@....com>,
        "S-k, Shyam-sundar" <Shyam-sundar.S-k@....com>
Cc:     "Mahapatra, Rajib" <Rajib.Mahapatra@....com>,
        Raul Rangel <rrangel@...omium.org>,
        Mark Gross <markgross@...nel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] platform/x86/amd: pmc: Add a workaround for an s0i3 issue
 on Cezanne

Hi,

On 11/17/22 17:06, Limonciello, Mario wrote:
> [Public]
> 
> 
> 
>> -----Original Message-----
>> From: Hans de Goede <hdegoede@...hat.com>
>> Sent: Thursday, November 17, 2022 08:06
>> To: Limonciello, Mario <Mario.Limonciello@....com>; S-k, Shyam-sundar
>> <Shyam-sundar.S-k@....com>
>> Cc: Mahapatra, Rajib <Rajib.Mahapatra@....com>; Raul Rangel
>> <rrangel@...omium.org>; Mark Gross <markgross@...nel.org>; platform-
>> driver-x86@...r.kernel.org; linux-kernel@...r.kernel.org
>> Subject: Re: [PATCH] platform/x86/amd: pmc: Add a workaround for an s0i3
>> issue on Cezanne
>>
>> Hi Mario,
>>
>> On 11/16/22 16:43, Mario Limonciello wrote:
>>> Cezanne platforms under the right circumstances have a synchronization
>>> problem where attempting to enter s2idle may fail if the x86 cores are
>>> put into HLT before hardware resume from the previous attempt has
>>> completed.
>>>
>>> To avoid this issue add a 10-20ms delay before entering s2idle another
>>> time. This workaround will only be applied on interrupts that wake the
>>> hardware but don't break the s2idle loop.
>>>
>>> Cc: "Mahapatra, Rajib" <Rajib.Mahapatra@....com>
>>> Cc: "Raul Rangel" <rrangel@...omium.org>
>>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>>
>> Thank you for your patch, I've applied this patch to my review-hans
>> branch:
>> https://git.k
 ernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fpdx86%2Fplatform-
>> drivers-x86.git%2Flog%2F%3Fh%3Dreview-
>> hans&amp;data=05%7C01%7Cmario.limonciello%40amd.com%7C674f8bf7a8
>> 114f83a3b408dac8a4d941%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C
>> 0%7C638042907591739047%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLj
>> AwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%
>> 7C%7C&amp;sdata=XYwl%2FOvUFy%2Bgz9EY9oa35M%2BkLf%2Bud8PKXynQ
>> FlrUdoE%3D&amp;reserved=0
>>
>> Please let me know if it important to get this as a fix into 6.1,
>> I wasn't really planning on doing any more fixes pull-reqs for 6.1,
>> but I can do one if necessary.
>>
> 
> AFAIK it's a corner case.  I think it can wait until 6.2, but I think it should probably
> be Cc to 6.1 stable (which has the ability to run code in the check()) phase.

Ok, I have added a:

Cc: stable@...r.kernel.org # 6.1

to the commit msg.

Regards,

Hans



>>> ---
>>>  drivers/platform/x86/amd/pmc.c | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/drivers/platform/x86/amd/pmc.c
>> b/drivers/platform/x86/amd/pmc.c
>>> index ef4ae977b8e0..439d282aafd1 100644
>>> --- a/drivers/platform/x86/amd/pmc.c
>>> +++ b/drivers/platform/x86/amd/pmc.c
>>> @@ -739,8 +739,14 @@ static void amd_pmc_s2idle_prepare(void)
>>>  static void amd_pmc_s2idle_check(void)
>>>  {
>>>  	struct amd_pmc_dev *pdev = &pmc;
>>> +	struct smu_metrics table;
>>>  	int rc;
>>>
>>> +	/* CZN: Ensure that future s0i3 entry attempts at least 10ms passed
>> */
>>> +	if (pdev->cpu_id == AMD_CPU_ID_CZN &&
>> !get_metrics_table(pdev, &table) &&
>>> +	    table.s0i3_last_entry_status)
>>> +		usleep_range(10000, 20000);
>>> +
>>>  	/* Dump the IdleMask before we add to the STB */
>>>  	amd_pmc_idlemask_read(pdev, pdev->dev, NULL);
>>>
>