[PATCH 3/3] soc: imx: gpcv2: split PGC domain probe in two passes

[Lucas Stach]

Since 5a46079a9645 ("PM: domains: Delete usage of driver_deferred_probe_check_state()")
power domain consumers attached by the driver core do not support probe
deferral anymore, as it is assumed that they are only probed after the
provider is present, as a devlink should have been established between
the two.

With the GPCv2 and its slightly unusual mix between platform devices and DT
description for the PGC domains, devlink fails to add the neccessary probe
dependency. Now that probe deferral is not an option anymore, the domain
drivers for nested GPC domains simply fail to probe, leaving parts of the
SoC unusable. Rather than trying to teach devlink about our one-off usage
of DT and platform devices, just split the registration of the nested
power domains into a second pass, so that we never need any dependency
handling.

Fixes: 5a46079a9645 ("PM: domains: Delete usage of driver_deferred_probe_check_state()")
Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
---
 drivers/soc/imx/gpcv2.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
index 6383a4edc360..d1bbadbcb034 100644
--- a/drivers/soc/imx/gpcv2.c
+++ b/drivers/soc/imx/gpcv2.c
@@ -1446,7 +1446,7 @@ static int imx_gpcv2_probe(struct platform_device *pdev)
 	struct device_node *pgc_np, *np;
 	struct regmap *regmap;
 	void __iomem *base;
-	int ret;
+	int ret, pass = 0;
 
 	pgc_np = of_get_child_by_name(dev->of_node, "pgc");
 	if (!pgc_np) {
@@ -1465,7 +1465,16 @@ static int imx_gpcv2_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/*
+	 * Run two passes for the registration of the PGC domain platform
+	 * devices: first all devices that are not part of a power-domain
+	 * themselves, then all the others. This avoids -EPROBE_DEFER being
+	 * returned for nested domains, that need their parent PGC domains
+	 * to be present on probe.
+	 */
+again:
 	for_each_child_of_node(pgc_np, np) {
+		bool child_domain = of_property_read_bool(np, "power-domains");
 		struct platform_device *pd_pdev;
 		struct imx_pgc_domain *domain;
 		u32 domain_index;
@@ -1473,6 +1482,9 @@ static int imx_gpcv2_probe(struct platform_device *pdev)
 		if (!of_device_is_available(np))
 			continue;
 
+		if ((pass == 0 && child_domain) || (pass == 1 && !child_domain))
+			continue;
+
 		ret = of_property_read_u32(np, "reg", &domain_index);
 		if (ret) {
 			dev_err(dev, "Failed to read 'reg' property\n");
@@ -1522,6 +1534,11 @@ static int imx_gpcv2_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (pass == 0) {
+		pass++;
+		goto again;
+	}
+
 	return 0;
 }
 
-- 
2.30.2