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SubjectRe: [PATCH v3 2/3] opp/of: Allow empty opp-table with opp-shared
On 02-11-20, 12:01, Nicola Mazzucato wrote:
> 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;

I am not sure I understand the reasoning behind this.

> 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

--
viresh

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