[PATCH 2/2] soc: imx: gpcv2: prepare bus clocks early

[Lucas Stach]

Prepare the bus clocks during PGC domain driver probe. This avoids a
potential deadlock when there a clock providers inside the domain,
as this might end up trying to take the CCF prepare_lock from two
different contexts, when runtime PM is trying to resume the PGC domain
for the clock provider. By keeping the bus clocks prepared as long as
there is a PGC domain driver attached, we don't need to take the
prepare_lock in the domain power up/down paths.

We don't want to do this for regular reset clocks, as this might lead
to some PLLs being kept prepared that could otherwise be shut down.
For the bus clocks this isn't a concern, as all the bus clocks are
derived from always-on system PLLs.

Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
---
 drivers/soc/imx/gpcv2.c | 41 ++++++++++++++++++++++++++++++++++-------
 1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
index 706f852e5d87..428e2fd82f26 100644
--- a/drivers/soc/imx/gpcv2.c
+++ b/drivers/soc/imx/gpcv2.c
@@ -337,10 +337,14 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
 
 	reset_control_assert(domain->reset);
 
-	/* Enable reset clocks for all devices in the domain */
-	ret = clk_bulk_prepare_enable(domain->num_clks, domain->clks);
+	if (!domain->bus_clocks)
+		/* Enable reset clocks for all devices in the domain */
+		ret = clk_bulk_prepare_enable(domain->num_clks, domain->clks);
+	else
+		/* Enable bus clocks for this domain */
+		ret = clk_bulk_enable(domain->num_clks, domain->clks);
 	if (ret) {
-		dev_err(domain->dev, "failed to enable reset clocks\n");
+		dev_err(domain->dev, "failed to enable clocks\n");
 		goto out_regulator_disable;
 	}
 
@@ -402,7 +406,10 @@ static int imx_pgc_power_up(struct generic_pm_domain *genpd)
 	return 0;
 
 out_clk_disable:
-	clk_bulk_disable_unprepare(domain->num_clks, domain->clks);
+	if (!domain->bus_clocks)
+		clk_bulk_disable_unprepare(domain->num_clks, domain->clks);
+	else
+		clk_bulk_disable(domain->num_clks, domain->clks);
 out_regulator_disable:
 	if (!IS_ERR(domain->regulator))
 		regulator_disable(domain->regulator);
@@ -466,8 +473,11 @@ static int imx_pgc_power_down(struct generic_pm_domain *genpd)
 		}
 	}
 
-	/* Disable reset clocks for all devices in the domain */
-	clk_bulk_disable_unprepare(domain->num_clks, domain->clks);
+	/* Disable bus or reset clocks for all devices in the domain */
+	if (!domain->bus_clocks)
+		clk_bulk_disable_unprepare(domain->num_clks, domain->clks);
+	else
+		clk_bulk_disable(domain->num_clks, domain->clks);
 
 	if (!IS_ERR(domain->regulator)) {
 		ret = regulator_disable(domain->regulator);
@@ -486,6 +496,8 @@ static int imx_pgc_power_down(struct generic_pm_domain *genpd)
 out_clk_disable:
 	if (!domain->bus_clocks)
 		clk_bulk_disable_unprepare(domain->num_clks, domain->clks);
+	else
+		clk_bulk_disable(domain->num_clks, domain->clks);
 
 	return ret;
 }
@@ -1343,10 +1355,19 @@ static int imx_pgc_domain_probe(struct platform_device *pdev)
 		regmap_update_bits(domain->regmap, domain->regs->map,
 				   domain->bits.map, domain->bits.map);
 
+	if (domain->bus_clocks) {
+		ret = clk_bulk_prepare(domain->num_clks, domain->clks);
+		if (ret) {
+			dev_err(domain->dev,
+				"Failed to prepare domain's clocks\n");
+			goto out_domain_unmap;
+		}
+	}
+
 	ret = pm_genpd_init(&domain->genpd, NULL, true);
 	if (ret) {
 		dev_err(domain->dev, "Failed to init power domain\n");
-		goto out_domain_unmap;
+		goto out_disable_clocks;
 	}
 
 	if (IS_ENABLED(CONFIG_LOCKDEP) &&
@@ -1364,6 +1385,9 @@ static int imx_pgc_domain_probe(struct platform_device *pdev)
 
 out_genpd_remove:
 	pm_genpd_remove(&domain->genpd);
+out_disable_clocks:
+	if (domain->bus_clocks)
+		clk_bulk_unprepare(domain->num_clks, domain->clks);
 out_domain_unmap:
 	if (domain->bits.map)
 		regmap_update_bits(domain->regmap, domain->regs->map,
@@ -1380,6 +1404,9 @@ static int imx_pgc_domain_remove(struct platform_device *pdev)
 	of_genpd_del_provider(domain->dev->of_node);
 	pm_genpd_remove(&domain->genpd);
 
+	if (domain->bus_clocks)
+		clk_bulk_unprepare(domain->num_clks, domain->clks);
+
 	if (domain->bits.map)
 		regmap_update_bits(domain->regmap, domain->regs->map,
 				   domain->bits.map, 0);
-- 
2.39.2