From: Heiner Kallweit <hkallweit1@gmail.com>
To: Lukas Wunner <lukas@wunner.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Bjorn Helgaas <helgaas@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Bjorn Helgaas <bhelgaas@google.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Kai Heng Feng <kai.heng.feng@canonical.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Time to re-enable Runtime PM per default for PCI devcies?
Date: Thu, 31 Dec 2020 10:38:12 +0100 [thread overview]
Message-ID: <4eb10092-e3f9-c9be-2dec-e6de8aeedf97@gmail.com> (raw)
In-Reply-To: <20201231040735.GA2075@wunner.de>
On 31.12.2020 05:07, Lukas Wunner wrote:
> On Wed, Dec 30, 2020 at 11:56:04PM +0100, Heiner Kallweit wrote:
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -3024,7 +3024,9 @@ void pci_pm_init(struct pci_dev *dev)
>> u16 status;
>> u16 pmc;
>>
>> - pm_runtime_forbid(&dev->dev);
>> + if (pci_acpi_forbid_runtime_pm())
>> + pm_runtime_forbid(&dev->dev);
>> +
>
> Generic PCI code usually does not call ACPI-specific functions directly,
> but rather through a pci_platform_pm_ops callback.
>
> FWIW, if platform_pci_power_manageable() returns true, it can probably
> be assumed that allowing runtime PM by default is okay. So as a first
> step, you may want to call that instead of adding a new callback.
>
I don't think that's sufficient. Most likely all the broken old systems
return true for platform_pci_power_manageable(). So yes, most likely
we'd need a new callback if we want to have the platform ops abstraction.
But it could be an optional callback, something like: forbid_runtime_pm
The question is just: is it worth it?
By the way: pci_set_platform_pm() returns an error if a callback isn't
set, but no existing caller bothers to check the return code.
> Thanks,
>
> Lukas
>
Heiner
next prev parent reply other threads:[~2020-12-31 9:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-17 15:56 Time to re-enable Runtime PM per default for PCI devcies? Heiner Kallweit
2020-11-17 16:38 ` Bjorn Helgaas
2020-11-17 16:57 ` Rafael J. Wysocki
2020-12-26 15:26 ` Heiner Kallweit
2020-12-29 11:56 ` Kai-Heng Feng
2020-12-29 21:11 ` Heiner Kallweit
2020-12-30 22:56 ` Heiner Kallweit
2020-12-31 4:07 ` Lukas Wunner
2020-12-31 9:38 ` Heiner Kallweit [this message]
2020-12-31 9:52 ` Heiner Kallweit
2021-01-04 17:39 ` Lukas Wunner
2021-01-04 20:32 ` Heiner Kallweit
2020-12-29 11:30 ` Lukas Wunner
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