[Intel-gfx] [PATCH v4] PCI / PM: tune down RPM suspend error message with EBUSY and EAGAIN retval

[Rafael J. Wysocki]

On Saturday, November 28, 2015 10:34:24 AM Imre Deak wrote:
> The runtime PM core doesn't treat EBUSY and EAGAIN retvals from the driver
> suspend hooks as errors, but they still show up as errors in dmesg. Tune
> them down.
> 
> One problem caused by this was noticed by Daniel: the i915 driver
> returns EAGAIN to signal a temporary failure to suspend and as a request
> towards the RPM core for scheduling a suspend again. This is a normal
> event, but the resulting error message flags a breakage during the
> driver's automated testing which parses dmesg and picks up the error.
> 
> v2:
> - fix compile breake when CONFIG_PM_SLEEP=n (0-day builder)
> v3:
> - instead of modifying the suspend_report_result() helper to disinguish
>   between the runtime and system suspend case, inline the error
>   printing, it's not used anywhere else (Rafael)
> v4:
> - don't refer to log levels as flags in code comment (Rafael)
> - use pr_debug(), pr_err() instead of the corresponding printk() (Rafael)
> 
> Reported-by: Daniel Vetter <daniel.vetter at intel.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92992
> CC: Bjorn Helgaas <bhelgaas at google.com>
> CC: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
> Signed-off-by: Imre Deak <imre.deak at intel.com>

This is fine by me.

Bjorn, any objections against applying it?  It reduces log noise quite
a bit for i915.

> ---
>  drivers/pci/pci-driver.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 4446fcb..32a9947 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -1146,9 +1146,21 @@ static int pci_pm_runtime_suspend(struct device *dev)
>  	pci_dev->state_saved = false;
>  	pci_dev->no_d3cold = false;
>  	error = pm->runtime_suspend(dev);
> -	suspend_report_result(pm->runtime_suspend, error);
> -	if (error)
> +	if (error) {
> +		/*
> +		 * -EBUSY and -EAGAIN is used to request the runtime PM core
> +		 * to schedule a new suspend, so log the event only with debug
> +		 * log level.
> +		 */
> +		if (error == -EBUSY || error == -EAGAIN)
> +			pr_debug("%s(): %pF returns %d\n", __func__,
> +				 pm->runtime_suspend, error);
> +		else
> +			pr_err("%s(): %pF returns %d\n", __func__,
> +			       pm->runtime_suspend, error);
> +
>  		return error;
> +	}
>  	if (!pci_dev->d3cold_allowed)
>  		pci_dev->no_d3cold = true;
>  
> 

Thanks,
Rafael