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Subject[PATCH v3 2/3] opp/of: Allow empty opp-table with opp-shared
Date
The opp binding now allows to have an empty opp table and shared-opp to
merely describe a hw connection among devices (f/v lines).

When initialising an opp table, allow such case by:
- treating some errors as warnings
- do not mark empty tables as shared
- don't fail on empty table

Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
---
drivers/opp/of.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index 874b58756220..b0230490bb31 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -157,6 +157,11 @@ static void _opp_table_free_required_tables(struct opp_table *opp_table)
/*
* Populate all devices and opp tables which are part of "required-opps" list.
* Checking only the first OPP node should be enough.
+ *
+ * Corner case: empty opp table and opp-shared found. In this case we set
+ * unconditionally the opp table access to exclusive, as the opp-shared property
+ * is used purely to describe hw connections. Such information will be retrieved
+ * via dev_pm_opp_of_get_sharing_cpus().
*/
static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
struct device *dev,
@@ -169,7 +174,9 @@ 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");
+
+ opp_table->shared_opp = OPP_TABLE_ACCESS_EXCLUSIVE;
return;
}

@@ -377,7 +384,9 @@ 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
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