Commit 9ec87c59 authored by Ulf Hansson's avatar Ulf Hansson
Browse files

OPP: Fix support for required OPPs for multiple PM domains 



It has turned out that having _set_required_opps() to recursively call
dev_pm_opp_set_opp() to set the required OPPs, doesn't really work as well
as we expected.

More precisely, at each recursive call to dev_pm_opp_set_opp() we are
changing an OPP for a required_dev that belongs to a required-OPP table.
The problem with this, is that we may have several devices sharing the same
required-OPP table, which leads to an incorrect behaviour in regards to
aggregating the per device votes.

To fix the problem for a required-OPP table belonging to a PM domain, which
is the only existing usecase for now, let's simply replace the call to
dev_pm_opp_set_opp() in _set_required_opps() by a call to _set_opp_level().

Moving forward we may potentially need to add support for other types of
required-OPP tables. In this case, the aggregation needs to be thought of.

Fixes: e37440e7 ("OPP: Call dev_pm_opp_set_opp() for required OPPs")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20240822224547.385095-2-ulf.hansson@linaro.org
parent 52dd070c

drivers/opp/core.c

+22 −34
Original line number Diff line number Diff line
@@ -1061,6 +1061,27 @@ static int _set_opp_bw(const struct opp_table *opp_table, 
	return 0;

}



static int _set_opp_level(struct device *dev, struct dev_pm_opp *opp)

{

	unsigned int level = 0;

	int ret = 0;



	if (opp) {

		if (opp->level == OPP_LEVEL_UNSET)

			return 0;



		level = opp->level;

	}



	/* Request a new performance state through the device's PM domain. */

	ret = dev_pm_domain_set_performance_state(dev, level);

	if (ret)

		dev_err(dev, "Failed to set performance state %u (%d)\n", level,

			ret);



	return ret;

}



/* This is only called for PM domain for now */

static int _set_required_opps(struct device *dev, struct opp_table *opp_table,

			      struct dev_pm_opp *opp, bool up)
@@ -1091,7 +1112,7 @@ static int _set_required_opps(struct device *dev, struct opp_table *opp_table, 
		if (devs[index]) {

			required_opp = opp ? opp->required_opps[index] : NULL;



			ret = dev_pm_opp_set_opp(devs[index], required_opp);

			ret = _set_opp_level(devs[index], required_opp);

			if (ret)

				return ret;

		}
@@ -1102,27 +1123,6 @@ static int _set_required_opps(struct device *dev, struct opp_table *opp_table, 
	return 0;

}



static int _set_opp_level(struct device *dev, struct dev_pm_opp *opp)

{

	unsigned int level = 0;

	int ret = 0;



	if (opp) {

		if (opp->level == OPP_LEVEL_UNSET)

			return 0;



		level = opp->level;

	}



	/* Request a new performance state through the device's PM domain. */

	ret = dev_pm_domain_set_performance_state(dev, level);

	if (ret)

		dev_err(dev, "Failed to set performance state %u (%d)\n", level,

			ret);



	return ret;

}



static void _find_current_opp(struct device *dev, struct opp_table *opp_table)

{

	struct dev_pm_opp *opp = ERR_PTR(-ENODEV);
@@ -2457,18 +2457,6 @@ static int _opp_attach_genpd(struct opp_table *opp_table, struct device *dev, 
			}

		}



		/*

		 * Add the virtual genpd device as a user of the OPP table, so

		 * we can call dev_pm_opp_set_opp() on it directly.

		 *

		 * This will be automatically removed when the OPP table is

		 * removed, don't need to handle that here.

		 */

		if (!_add_opp_dev(virt_dev, opp_table->required_opp_tables[index])) {

			ret = -ENOMEM;

			goto err;

		}



		opp_table->required_devs[index] = virt_dev;

		index++;

		name++;