From 24b3c963c0108f3da6d978d74a745c824ab551dc Mon Sep 17 00:00:00 2001 From: Nicola Mazzucato Date: Tue, 8 Dec 2020 17:42:26 +0000 Subject: dt-bindings: opp: Allow empty OPP tables Currently the optional property opp-shared is used within an opp table to tell that a set of devices share their clock/voltage lines (and the OPP points). It is therefore possible to use an empty OPP table to convey only that information, useful in situations where the opp points are provided via other means (hardware. firmware, etc). Update the documentation to remark this additional case and provide an example. Signed-off-by: Nicola Mazzucato Signed-off-by: Viresh Kumar --- Documentation/devicetree/bindings/opp/opp.txt | 54 ++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt index 9847dfeeffcb..08b3da4736cf 100644 --- a/Documentation/devicetree/bindings/opp/opp.txt +++ b/Documentation/devicetree/bindings/opp/opp.txt @@ -65,7 +65,9 @@ Required properties: - OPP nodes: One or more OPP nodes describing voltage-current-frequency combinations. Their name isn't significant but their phandle can be used to - reference an OPP. + reference an OPP. These are mandatory except for the case where the OPP table + is present only to indicate dependency between devices using the opp-shared + property. Optional properties: - opp-shared: Indicates that device nodes using this OPP Table Node's phandle @@ -568,3 +570,53 @@ Example 6: opp-microvolt-, opp-microamp-: }; }; }; + +Example 7: Single cluster Quad-core ARM cortex A53, OPP points from firmware, +distinct clock controls but two sets of clock/voltage/current lines. + +/ { + cpus { + #address-cells = <2>; + #size-cells = <0>; + + cpu@0 { + compatible = "arm,cortex-a53"; + reg = <0x0 0x100>; + next-level-cache = <&A53_L2>; + clocks = <&dvfs_controller 0>; + operating-points-v2 = <&cpu_opp0_table>; + }; + cpu@1 { + compatible = "arm,cortex-a53"; + reg = <0x0 0x101>; + next-level-cache = <&A53_L2>; + clocks = <&dvfs_controller 1>; + operating-points-v2 = <&cpu_opp0_table>; + }; + cpu@2 { + compatible = "arm,cortex-a53"; + reg = <0x0 0x102>; + next-level-cache = <&A53_L2>; + clocks = <&dvfs_controller 2>; + operating-points-v2 = <&cpu_opp1_table>; + }; + cpu@3 { + compatible = "arm,cortex-a53"; + reg = <0x0 0x103>; + next-level-cache = <&A53_L2>; + clocks = <&dvfs_controller 3>; + operating-points-v2 = <&cpu_opp1_table>; + }; + + }; + + cpu_opp0_table: opp0_table { + compatible = "operating-points-v2"; + opp-shared; + }; + + cpu_opp1_table: opp1_table { + compatible = "operating-points-v2"; + opp-shared; + }; +}; -- cgit v1.2.3 From 6ee70e8c34e37a34f4dc2c8bc06febffd375fac4 Mon Sep 17 00:00:00 2001 From: Nicola Mazzucato Date: Tue, 8 Dec 2020 17:42:27 +0000 Subject: 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 Signed-off-by: Viresh Kumar --- 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 874b58756220..96113fc0e18c 100644 --- a/drivers/opp/of.c +++ b/drivers/opp/of.c @@ -169,7 +169,8 @@ 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; } @@ -377,7 +378,9 @@ 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; -- cgit v1.2.3