On Tue, Feb 27, 2024 at 11:56:48AM +0530, Raag Jadav wrote:
> Commit c5eb1190074c ("PCI / PM: Allow runtime PM without callback
> functions") tried to eliminate the need for runtime PM callbacks by
> modifying pci_pm_runtime_suspend() and pci_pm_runtime_resume(), but
> didn't modify pci_pm_runtime_idle() with relevant changes, which still
> returns -ENOSYS if the driver supplies no runtime PM callbacks.
>
> Modify pci_pm_runtime_idle() such that it allows PCI device power state
> transitions without runtime PM callbacks and complete the original
> intention of commit c5eb1190074c ("PCI / PM: Allow runtime PM without
> callback functions").
>
> Signed-off-by: Raag Jadav <raag.jadav@xxxxxxxxx>
> Acked-by: Rafael J. Wysocki <rafael@xxxxxxxxxx>
> Tested-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@xxxxxxxxxxxxxxx>
Applied to pci/pm for v6.9, thanks!
I updated the commit log to try to clarify which drivers would be
affected. Now that I worked through those details, I see that it was
all there from the beginning and it just took a long time to sink into
my head:
PCI/PM: Allow runtime PM with no PM callbacks at all
Commit c5eb1190074c ("PCI / PM: Allow runtime PM without callback
functions") eliminated the need for PM callbacks in
pci_pm_runtime_suspend() and pci_pm_runtime_resume(), but
didn't do the same for pci_pm_runtime_idle().
Therefore, runtime suspend worked as long as the driver implemented at
least one PM callback. But if the driver doesn't implement any PM
callbacks at all (driver->pm is NULL), pci_pm_runtime_idle() returned
-ENOSYS, which prevented runtime suspend.
Modify pci_pm_runtime_idle() to allow PCI device power state transitions
without runtime PM callbacks and complete the original intention of commit
c5eb1190074c ("PCI / PM: Allow runtime PM without callback functions").
Bjorn
> ---
>
> This is not marked for linux-stable for the need of extensive testing
> and can be backported after a few releases if no issues are reported.
>
> Changes since v1:
> - Update commit message and tags
>
> drivers/pci/pci-driver.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 51ec9e7e784f..bb7f6775b350 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -1382,10 +1382,7 @@ static int pci_pm_runtime_idle(struct device *dev)
> if (!pci_dev->driver)
> return 0;
>
> - if (!pm)
> - return -ENOSYS;
> -
> - if (pm->runtime_idle)
> + if (pm && pm->runtime_idle)
> return pm->runtime_idle(dev);
>
> return 0;
> --
> 2.35.3
>
