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Message-ID: <06cf76ba-de5f-caaa-d1c4-9d34adf15a52@amd.com>
Date:   Thu, 3 Aug 2023 06:38:45 -0500
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Subject: Re: [PATCH v8 2/2] PCI/ACPI: Use device constraints instead of dates
 to opt devices into D3
Content-Language: en-US
To:     Mika Westerberg <mika.westerberg@linux.intel.com>
Cc:     "Rafael J . Wysocki" <rafael@kernel.org>,
        Bjorn Helgaas <helgaas@kernel.org>, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
        Iain Lane <iain@orangesquash.org.uk>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
References: <20230802201013.910-1-mario.limonciello@amd.com>
 <20230802201013.910-3-mario.limonciello@amd.com>
 <20230803050118.GV14638@black.fi.intel.com>
From:   Mario Limonciello <mario.limonciello@amd.com>
In-Reply-To: <20230803050118.GV14638@black.fi.intel.com>
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On 8/3/23 00:01, Mika Westerberg wrote:
> Hi,
> 
> On Wed, Aug 02, 2023 at 03:10:13PM -0500, Mario Limonciello wrote:
>> @@ -3036,11 +3044,8 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
>>   		if (dmi_check_system(bridge_d3_blacklist))
>>   			return false;
>>   
>> -		/*
>> -		 * It should be safe to put PCIe ports from 2015 or newer
>> -		 * to D3.
>> -		 */
>> -		if (dmi_get_bios_year() >= 2015)
>> +		/* the platform indicates in a device constraint that D3 is needed */
>> +		if (platform_constraint_d3(bridge))
> 
> This for sure causes some sort of power regression on the Intel
> platforms made after 2015. Why not check for the constraint and:
> 
Are you sure?  I saw it as an explanation of how Windows could put the 
systems into D3 when there is no other PM related ACPI objects.

> - If present and enabled, use the desired D-state
> - If present and disabled, leave the device in D0
> - If not present use the existing cutoff date
> 
> ?

Thanks! That sounds very reasonable to me.  I'll double check it in my case.