[RFC v2 02/11] OPP: Make dev_pm_opp_set_rate() with freq=0 as valid

[Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>]

For devices with performance state, we use dev_pm_opp_set_rate()
to set the appropriate clk rate and the performance state.
We do need a way to *remove* the performance state vote when
we idle the device and turn the clocks off. Use dev_pm_opp_set_rate()
with freq=0 to achieve this.

Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---
 drivers/opp/core.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index bc9a7762dd4c..d6acc880676e 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -708,18 +708,24 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 	struct clk *clk;
 	int ret;
 
-	if (unlikely(!target_freq)) {
-		dev_err(dev, "%s: Invalid target frequency %lu\n", __func__,
-			target_freq);
-		return -EINVAL;
-	}
-
 	opp_table = _find_opp_table(dev);
 	if (IS_ERR(opp_table)) {
 		dev_err(dev, "%s: device opp doesn't exist\n", __func__);
 		return PTR_ERR(opp_table);
 	}
 
+	if (unlikely(!target_freq)) {
+		if (opp_table->required_opp_tables) {
+			/* drop the performance state vote */
+			dev_pm_genpd_set_performance_state(dev, 0);
+			return 0;
+		} else {
+			dev_err(dev, "%s: Invalid target frequency %lu\n", __func__,
+				target_freq);
+			return -EINVAL;
+		}
+	}
+
 	clk = opp_table->clk;
 	if (IS_ERR(clk)) {
 		dev_err(dev, "%s: No clock available for the device\n",
-- 
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