linux-kernel - [PATCH v3 11/12] opp: Handle missing OPP table in dev_pm_opp_xlate_performance

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Date:   Mon, 18 Jan 2021 03:55:23 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>, Nishanth Menon <nm@...com>,
        Yangtao Li <tiny.windzz@...il.com>,
        Matt Merhar <mattmerhar@...tonmail.com>
Cc:     linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: [PATCH v3 11/12] opp: Handle missing OPP table in dev_pm_opp_xlate_performance_state()

NVIDIA Tegra SoCs have a power domains topology such that child domains
only clamp a power rail, while parent domain controls shared performance
state of the multiple child domains. In this case child's domain doesn't
need to have OPP table. Hence we want to allow children power domains to
pass performance state to the parent domain if child's domain doesn't have
OPP table.

The dev_pm_opp_xlate_performance_state() gets src_table=NULL if a child
power domain doesn't have OPP table and in this case we should pass the
performance state to the parent domain.

Tested-by: Peter Geis <pgwipeout@...il.com>
Tested-by: Nicolas Chauvet <kwizart@...il.com>
Tested-by: Matt Merhar <mattmerhar@...tonmail.com>
Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/opp/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 7726c4c40b53..ca8c6acc29f4 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2419,7 +2419,7 @@ int dev_pm_opp_xlate_performance_state(struct opp_table *src_table,
 	 * and so none of them have the "required-opps" property set. Return the
 	 * pstate of the src_table as it is in such cases.
 	 */
-	if (!src_table->required_opp_count)
+	if (!src_table || !src_table->required_opp_count)
 		return pstate;
 
 	for (i = 0; i < src_table->required_opp_count; i++) {
-- 
2.29.2