[RFC PATCH v6 5/9] pmdomain/rockchip: cycle optional power-domain resets on power-on

[Jiaxing Hu <gahing@gahingwoo.com>]

Some Rockchip domains come out of power-on with their bus interface in
an undefined state. On the RK3576 NPU this shows up as a hang on the
first register access after the domain is switched on, and pulsing the
domain's resets at this point clears it.

Take the domain node's resets if it has any, and pulse them between
releasing idle and restoring QoS. The resets are optional, so domains
that do not list any are unaffected.

Signed-off-by: Jiaxing Hu <gahing@gahingwoo.com>
---
 drivers/pmdomain/rockchip/pm-domains.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/pmdomain/rockchip/pm-domains.c b/drivers/pmdomain/rockchip/pm-domains.c
index e1857f878..4eebb5d99 100644
--- a/drivers/pmdomain/rockchip/pm-domains.c
+++ b/drivers/pmdomain/rockchip/pm-domains.c
@@ -19,6 +19,7 @@
 #include <linux/of_clk.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/reset.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/mfd/syscon.h>
@@ -103,6 +104,7 @@ struct rockchip_pm_domain {
 	struct clk_bulk_data *clks;
 	struct device_node *node;
 	struct regulator *supply;
+	struct reset_control *resets;
 };
 
 struct rockchip_pmu {
@@ -688,6 +690,13 @@ static int rockchip_pd_power(struct rockchip_pm_domain *pd, bool power_on)
 		if (pd->info->delay_us)
 			udelay(pd->info->delay_us);
 
+		/* Optional: some domains need their resets cycled after power-on. */
+		if (pd->resets) {
+			reset_control_assert(pd->resets);
+			udelay(10);
+			reset_control_deassert(pd->resets);
+		}
+
 		rockchip_pmu_restore_qos(pd);
 	}
 
@@ -857,6 +866,14 @@ static int rockchip_pm_add_one_domain(struct rockchip_pmu *pmu,
 	if (error)
 		goto err_put_clocks;
 
+	pd->resets = of_reset_control_array_get_optional_exclusive(node);
+	if (IS_ERR(pd->resets)) {
+		error = dev_err_probe(pmu->dev, PTR_ERR(pd->resets),
+				      "%pOFn: failed to get resets\n", node);
+		pd->resets = NULL;
+		goto err_unprepare_clocks;
+	}
+
 	pd->num_qos = of_count_phandle_with_args(node, "pm_qos",
 						 NULL);
 
@@ -927,6 +944,7 @@ static int rockchip_pm_add_one_domain(struct rockchip_pmu *pmu,
 	clk_bulk_unprepare(pd->num_clks, pd->clks);
 err_put_clocks:
 	clk_bulk_put(pd->num_clks, pd->clks);
+	reset_control_put(pd->resets);
 	return error;
 }
 
@@ -945,6 +963,7 @@ static void rockchip_pm_remove_one_domain(struct rockchip_pm_domain *pd)
 
 	clk_bulk_unprepare(pd->num_clks, pd->clks);
 	clk_bulk_put(pd->num_clks, pd->clks);
+	reset_control_put(pd->resets);
 
 	/* protect the zeroing of pm->num_clks */
 	mutex_lock(&pd->pmu->mutex);
-- 
2.43.0