linux-kernel - [RFC/PATCH 1/5] OPP: Don't overwrite rounded clk rate

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Date:   Mon, 28 Jan 2019 17:55:43 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-serial@...r.kernel.org, linux-spi@...r.kernel.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Doug Anderson <dianders@...omium.org>
Subject: [RFC/PATCH 1/5] OPP: Don't overwrite rounded clk rate

Doing this allows us to call this API with any rate requested and have
it not need to match in the OPP table. Instead, we'll round the rate up
to the nearest OPP that we see so that we can get the voltage or level
that's required for that OPP. This supports users of OPP that want to
specify the 'fmax' tables of a device instead of every single frequency
that they need. And for devices that required the exact frequency, we
can rely on the clk framework to round the rate to the nearest supported
frequency instead of the OPP framework to do so.

Note that this may affect drivers that don't want the clk framework to
do rounding, but instead want the OPP table to do the rounding for them.
Do we have that case? Should we add some flag to the OPP table to
indicate this and then not have that flag set when there isn't an OPP
table for the device and also introduce a property like 'opp-use-clk' to
tell the table that it should use the clk APIs to round rates instead of
OPP?

Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---
 drivers/opp/core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index e06a0ab05ad6..b6516d623c5a 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -704,7 +704,7 @@ static int _set_required_opps(struct device *dev,
 int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 {
 	struct opp_table *opp_table;
-	unsigned long freq, old_freq;
+	unsigned long freq, opp_freq, old_freq, old_opp_freq;
 	struct dev_pm_opp *old_opp, *opp;
 	struct clk *clk;
 	int ret;
@@ -743,13 +743,15 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 		goto put_opp_table;
 	}

-	old_opp = _find_freq_ceil(opp_table, &old_freq);
+	old_opp_freq = old_freq;
+	old_opp = _find_freq_ceil(opp_table, &old_opp_freq);
 	if (IS_ERR(old_opp)) {
 		dev_err(dev, "%s: failed to find current OPP for freq %lu (%ld)\n",
 			__func__, old_freq, PTR_ERR(old_opp));
 	}

-	opp = _find_freq_ceil(opp_table, &freq);
+	opp_freq = freq;
+	opp = _find_freq_ceil(opp_table, &opp_freq);
 	if (IS_ERR(opp)) {
 		ret = PTR_ERR(opp);
 		dev_err(dev, "%s: failed to find OPP for freq %lu (%d)\n",
-- 
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