PM / Domains: Allow genpd to power on during system PM phases

If a 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.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Acked-by: Maruthi Bayyavarapu <maruthi.bayyavarapu@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 0 insertions, 23 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
index 252edba16e36..892d60fb225b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
@@ -421,29 +421,6 @@ static int acp_suspend(void *handle)
 
 static int acp_resume(void *handle)
 {
-	int i, ret;
-	struct acp_pm_domain *apd;
-	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
-
-	/* return early if no ACP */
-	if (!adev->acp.acp_genpd)
-		return 0;
-
-	/* SMU block will power on ACP irrespective of ACP runtime status.
-	 * Power off explicitly based on genpd ACP runtime status so that ACP
-	 * hw and ACP-genpd status are in sync.
-	 * 'suspend_power_off' represents "Power status before system suspend"
-	*/
-	if (adev->acp.acp_genpd->gpd.suspend_power_off == true) {
-		apd = container_of(&adev->acp.acp_genpd->gpd,
-					struct acp_pm_domain, gpd);
-
-		for (i = 4; i >= 0 ; i--) {
-			ret = acp_suspend_tile(apd->cgs_dev, ACP_TILE_P1 + i);
-			if (ret)
-				pr_err("ACP tile %d tile suspend failed\n", i);
-		}
-	}
 	return 0;
 }