Ulf Hansson <ulf.hansson@xxxxxxxxxx> writes: > If the PM domain is powered off when the first device starts its system PM > prepare phase, genpd prevents any further attempts to power on the PM > domain during the following system PM phases. Not until the system PM > complete phase is finalized for all devices in the PM domain, genpd again > allows it to be powered on. > > This behaviour needs to be changed, as a subsystem/driver for a device in > the same PM domain may still need to be able to serve requests in some of > the system PM phases. Accordingly, it may need to runtime resume its > device and thus also request the corresponding PM domain to be powered on. > > To deal with these scenarios, let's make the device operational in the > system PM prepare phase by runtime resuming it, no matter if the PM domain > is powered on or off. Changing this also enables us to remove genpd's > suspend_power_off flag, as it's being used to track this condition. > Additionally, we must allow the PM domain to be powered on via runtime PM > during the system PM phases. > > This change also requires a fix in the AMD ACP (Audio CoProcessor) drm > driver. It registers a genpd to model the ACP as a PM domain, but > unfortunately it's also abuses genpd's "internal" suspend_power_off flag > to deal with a corner case at system PM resume. > > More precisely, the so called SMU block powers on the ACP at system PM > resume, unconditionally if it's being used or not. This may lead to that > genpd's internal status of the power state, may not correctly reflect the > power state of the HW after a system PM resume. > > Because of changing the behaviour of genpd, by runtime resuming devices in > the prepare phase, the AMD ACP drm driver no longer have to deal with this > corner case. So let's just drop the related code in this driver. > > Cc: David Airlie <airlied@xxxxxxxx> > Cc: Alex Deucher <alexander.deucher@xxxxxxx> > Cc: Christian König <christian.koenig@xxxxxxx> > Cc: Maruthi Srinivas Bayyavarapu <Maruthi.Bayyavarapu@xxxxxxx> > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx > Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > --- > > Changes in v3: > - Updated changelog. > > Changes in v2: > - Updated changelog. > - Added a fix in the AMD ACP (Audio CoProcessor) drm driver, which > registers a genpd. The fix removes the usage of genpd's internal > suspend_power_off flag as it's not needed after this change. Because of > this change I am also requesting an ack from the drm driver maintainer. > > > --- > drivers/base/power/domain.c | 84 ++++++++++++--------------------- > drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c | 23 --------- > include/linux/pm_domain.h | 1 - For the PM core part: Reviewed-by: Kevin Hilman <khilman@xxxxxxxxxxxx> Acked-by: Kevin Hilman <khilman@xxxxxxxxxxxx> For the AMD DRM driver, the changes look right too, but I'm not confident enough about the intent of that to be sure. Kevin _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
