Re: [PATCH v1] PCI / PM: Really allow runtime PM without callback functions

Rafael J. Wysocki
2024-02-13T14:02:23Z

On Mon, Feb 12, 2024 at 7:32 AM Raag Jadav <raag.jadav@intel.com> 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.
>
> Fix this by modifying pci_pm_runtime_idle() such that it allows PCI
> device power state transitions without runtime PM callbacks.
>
> 0) | pm_runtime_work() {
> 0) | rpm_idle() {
> 0) | rpm_check_suspend_allowed() {
> 0) 1.500 us | __dev_pm_qos_resume_latency(); /* = 0x7fffffff */
> 0) 4.840 us | } /* rpm_check_suspend_allowed = 0x0 */
> 0) 1.550 us | __rpm_get_callback(); /* = 0xffffffffb4bc84f0 */
> 0) 1.800 us | pci_pm_runtime_idle(); /* = -38 */
> 0) + 17.070 us | } /* rpm_idle = -38 */
> 0) + 22.450 us | } /* pm_runtime_work = -38 */
>
> Debugged-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
> Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>

Acked-by: Rafael J. Wysocki <rafael@kernel.org>

> ---
>
> 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.
>
> 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
>
>