soc: mtk-pm-domains: do not register smi node as syscon

Mediatek requires mmsys clocks to be unprepared during suspend,
otherwise system has chances to hang.

syscon_regmap_lookup_by_phandle_optional() will attach and prepare the
first clock in smi node, leading to additional prepare to the clock
which is not balanced with the prepare/unprepare pair in resume/suspend
callbacks.

If a power domain node requests an smi node and the smi node's first
clock is an mmsys clock, it will results in an unstable suspend resume.

Fixes: f414854c ("soc: mediatek: pm-domains: Add SMI block as bus protection block")
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: chun-jie.chen <chun-jie.chen@mediatek.com>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210601035905.2970384-2-hsinyi@chromium.orgSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

drivers/soc/mediatek/mtk-pm-domains.c

@@ -297,6 +297,7 @@ generic_pm_domain *scpsys_add_one_domain(struct scpsys *scpsys, struct device_no
 	const struct scpsys_domain_data *domain_data;
 	struct scpsys_domain *pd;
 	struct device_node *root_node = scpsys->dev->of_node;
+	struct device_node *smi_node;
 	struct property *prop;
 	const char *clk_name;
 	int i, ret, num_clks;
@@ -352,9 +353,13 @@ generic_pm_domain *scpsys_add_one_domain(struct scpsys *scpsys, struct device_no
 	if (IS_ERR(pd->infracfg))
 		return ERR_CAST(pd->infracfg);
 
-	pd->smi = syscon_regmap_lookup_by_phandle_optional(node, "mediatek,smi");
-	if (IS_ERR(pd->smi))
-		return ERR_CAST(pd->smi);
+	smi_node = of_parse_phandle(node, "mediatek,smi", 0);
+	if (smi_node) {
+		pd->smi = device_node_to_regmap(smi_node);
+		of_node_put(smi_node);
+		if (IS_ERR(pd->smi))
+			return ERR_CAST(pd->smi);
+	}
 
 	num_clks = of_clk_get_parent_count(node);
 	if (num_clks > 0) {