[RFC] PM / OPP: Ignore missing supplies if a prop_name is set

Message ID 20180507125223.18508-1-thierry.escande@linaro.org
State New
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  • [RFC] PM / OPP: Ignore missing supplies if a prop_name is set
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Thierry Escande May 7, 2018, 12:52 p.m.
For a given frequency and prop_name, if a voltage supply entry is
missing in the opp-table defined in DT, the frequency was added anyway
to the opp tables with a voltage setting of 0.

With this patch, if a prop_name is set, frequencies with no
corresponding prop_name are ignored without failing.

Signed-off-by: Thierry Escande <thierry.escande@linaro.org>

---

For Qualcomm apq8064 SoCs, the opp-tables defined in the dts file
contain all frequencies supported by all SoC versions. But not all SoCs
support all frequencies and they are filtered out by a prop_name
containing a speed bin value and a pvs value both read from a fuse
register sets in factory. The speed bin defines the SoC version and the
voltage setting is defined by the pvs value in the form:

	opp-384000000 {
			opp-hz = /bits/ 64 <384000000>;
			opp-microvolt-speed0-pvs0-v0 = <950000>;
			opp-microvolt-speed0-pvs1-v0 = <900000>;
			...
			opp-microvolt-speed1-pvs0-v0 = <950000>;
			opp-microvolt-speed1-pvs1-v0 = <950000>;
			...
			opp-microvolt-speed2-pvs0-v0 = <950000>;
			opp-microvolt-speed2-pvs1-v0 = <950000>;
			opp-microvolt-speed2-pvs2-v0 = <925000>;
			opp-microvolt-speed2-pvs3-v0 = <900000>;
			...
		};

Since some opp-freq entries may not have properties for a particular
speed value the idea is to ignore a frequency if it does not contain a
property as "opp-microvolt-prop_name" nor one as "opp-microvolt" without
failing if the opp_table has a prop_name defined. Otherwise, there would
be unsupported frequencies reported as supported with a voltage setting
of zero.

This could affect SoCs that have a prop_name defined and no
"opp-microvolt" entry in the opp-table. I didn't spot any of these but
I'd like to have your opinion.

---
 drivers/opp/of.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

-- 
2.14.1

Patch

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index cb716aa2f44b..2efe69d619f3 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -132,6 +132,14 @@  static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev,
 
 		/* Missing property isn't a problem, but an invalid entry is */
 		if (!prop) {
+			/*
+			 * A prop_name is specified but no property found with
+			 * or without prop_name. Return ENOENT so the caller
+			 * knows the entry is missing.
+			 */
+			if (opp_table->prop_name)
+				return -ENOENT;
+
 			if (!opp_table->regulator_count)
 				return 0;
 
@@ -325,8 +333,11 @@  static int _opp_add_static_v2(struct opp_table *opp_table, struct device *dev,
 		new_opp->clock_latency_ns = val;
 
 	ret = opp_parse_supplies(new_opp, dev, opp_table);
-	if (ret)
+	if (ret) {
+		if (ret == -ENOENT)
+			ret = 0;
 		goto free_opp;
+	}
 
 	ret = _opp_add(dev, new_opp, opp_table);
 	if (ret) {