linux-kernel - [PATCH v4 2/4] opp/of: Allow empty opp-table with opp-shared

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Date:   Wed,  2 Dec 2020 17:23:54 +0000
From:   Nicola Mazzucato <nicola.mazzucato@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        sudeep.holla@....com, rjw@...ysocki.net, vireshk@...nel.org,
        robh+dt@...nel.org, sboyd@...nel.org, nm@...com
Cc:     daniel.lezcano@...aro.org, morten.rasmussen@....com,
        chris.redpath@....com, nicola.mazzucato@....com
Subject: [PATCH v4 2/4] opp/of: Allow empty opp-table with opp-shared

The opp binding now allows to have an empty opp table and shared-opp to
still describe that devices share v/f lines.

When initialising an empty opp table, allow such case by:
- treating such conditions with warnings in place of errors
- don't fail on empty table

Signed-off-by: Nicola Mazzucato <nicola.mazzucato@....com>
---
 drivers/opp/of.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index ffd937af8089..03cb387236c4 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -170,7 +170,8 @@ static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
 	/* Traversing the first OPP node is all we need */
 	np = of_get_next_available_child(opp_np, NULL);
 	if (!np) {
-		dev_err(dev, "Empty OPP table\n");
+		dev_warn(dev, "Empty OPP table\n");
+
 		return;
 	}
 
@@ -378,7 +379,9 @@ int dev_pm_opp_of_find_icc_paths(struct device *dev,
 	struct icc_path **paths;
 
 	ret = _bandwidth_supported(dev, opp_table);
-	if (ret <= 0)
+	if (ret == -EINVAL)
+		return 0; /* Empty OPP table is a valid corner-case, let's not fail */
+	else if (ret <= 0)
 		return ret;
 
 	ret = 0;
-- 
2.27.0