The patch, by informing pm_genpd_init() with the "is_off" parameter that
the power domain is already on, prevents the power_on() callback from being
called, thus avoiding the unnecessary repetition of the hardware power-on
procedure. This feature is crucial when supporting the simple framebuffer,
as the power domains have already been initialized by the bootloader.

Co-developed-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

 drivers/pmdomain/imx/imx8m-blk-ctrl.c | 51 ++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/drivers/pmdomain/imx/imx8m-blk-ctrl.c b/drivers/pmdomain/imx/imx8m-blk-ctrl.c
index ca942d7929c2..8dc1508571dd 100644
--- a/drivers/pmdomain/imx/imx8m-blk-ctrl.c
+++ b/drivers/pmdomain/imx/imx8m-blk-ctrl.c
@@ -166,6 +166,24 @@ static int imx8m_blk_ctrl_power_off(struct generic_pm_domain *genpd)
 
 static struct lock_class_key blk_ctrl_genpd_lock_class;
 
+static bool imx8m_blk_ctrl_is_off(struct device *dev, struct generic_pm_domain *genpd)
+{
+	struct device_node *node = dev->of_node;
+	struct imx8m_blk_ctrl_domain *domain = to_imx8m_blk_ctrl_domain(genpd);
+	const struct imx8m_blk_ctrl_domain_data *data = domain->data;
+	u32 boot_on;
+	int index;
+
+	index = of_property_match_string(node, "power-domain-names",
+					 data->gpc_name);
+	if (index < 0 || of_property_read_u32_index(node,
+						    "fsl,power-domains-boot-on",
+						    index, &boot_on))
+		return true;
+
+	return !boot_on;
+}
+
 static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
 {
 	const struct imx8m_blk_ctrl_data *bc_data;
@@ -173,6 +191,8 @@ static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
 	struct imx8m_blk_ctrl *bc;
 	void __iomem *base;
 	int i, ret;
+	bool init_off;
+	bool *pm_runtime_cleanup;
 
 	struct regmap_config regmap_config = {
 		.reg_bits	= 32,
@@ -221,6 +241,11 @@ static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
 					     "failed to attach power domain \"bus\"\n");
 	}
 
+	pm_runtime_cleanup = devm_kcalloc(dev, bc_data->num_domains,
+					  sizeof(*pm_runtime_cleanup), GFP_KERNEL);
+	if (!pm_runtime_cleanup)
+		return -ENOMEM;
+
 	for (i = 0; i < bc_data->num_domains; i++) {
 		const struct imx8m_blk_ctrl_domain_data *data = &bc_data->domains[i];
 		struct imx8m_blk_ctrl_domain *domain = &bc->domains[i];
@@ -274,7 +299,8 @@ static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
 		domain->genpd.power_off = imx8m_blk_ctrl_power_off;
 		domain->bc = bc;
 
-		ret = pm_genpd_init(&domain->genpd, NULL, true);
+		init_off = imx8m_blk_ctrl_is_off(dev, &domain->genpd);
+		ret = pm_genpd_init(&domain->genpd, NULL, init_off);
 		if (ret) {
 			dev_err_probe(dev, ret,
 				      "failed to init power domain \"%s\"\n",
@@ -283,6 +309,24 @@ static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
 			goto cleanup_pds;
 		}
 
+		if (!init_off) {
+			ret = pm_runtime_get_sync(bc->bus_power_dev);
+			if (ret < 0) {
+				pm_runtime_put_noidle(bc->bus_power_dev);
+				dev_err_probe(dev, ret, "failed to power up bus domain\n");
+				goto cleanup_pds;
+			}
+
+			ret = pm_runtime_get_sync(domain->power_dev);
+			if (ret < 0) {
+				pm_runtime_put(bc->bus_power_dev);
+				dev_err_probe(dev, ret, "failed to power up peripheral domain\n");
+				goto cleanup_pds;
+			}
+
+			pm_runtime_cleanup[i] = true;
+		}
+
 		/*
 		 * We use runtime PM to trigger power on/off of the upstream GPC
 		 * domain, as a strict hierarchical parent/child power domain
@@ -324,6 +368,11 @@ static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
 	of_genpd_del_provider(dev->of_node);
 cleanup_pds:
 	for (i--; i >= 0; i--) {
+		if (pm_runtime_cleanup[i]) {
+			pm_runtime_put(bc->domains[i].power_dev);
+			pm_runtime_put(bc->bus_power_dev);
+		}
+
 		pm_genpd_remove(&bc->domains[i].genpd);
 		dev_pm_domain_detach(bc->domains[i].power_dev, true);
 	}
-- 
2.43.0