linux-kernel - [PATCH 2/3] soc: mtk-pm-domains: do not register smi node as syscon

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Date:   Mon, 31 May 2021 12:35:01 +0800
From:   Hsin-Yi Wang <hsinyi@...omium.org>
To:     Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        chun-jie.chen@...iatek.corp-partner.google.com,
        Yong Wu <yong.wu@...iatek.com>
Subject: [PATCH 2/3] 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 unstabke suspend resume.

Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
---
 drivers/soc/mediatek/mtk-pm-domains.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-pm-domains.c b/drivers/soc/mediatek/mtk-pm-domains.c
index 536d8c64b2b4..a9ba71eee4bb 100644
--- a/drivers/soc/mediatek/mtk-pm-domains.c
+++ b/drivers/soc/mediatek/mtk-pm-domains.c
@@ -296,7 +296,7 @@ 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 *root_node = scpsys->dev->of_node, *smi_node;
 	struct property *prop;
 	const char *clk_name;
 	int i, ret, num_clks;
@@ -352,9 +352,13 @@ 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) {
-- 
2.32.0.rc0.204.g9fa02ecfa5-goog