[PATCH 08/22] clk: Take into account uncached clocks in clk_set_rate_range()

Maxime Ripard
2022-04-08T09:14:01Z

clk_set_rate_range() will use the last requested rate for the clock when
it calls into the driver set_rate hook.

However, if CLK_GET_RATE_NOCACHE is set on that clock, the last
requested rate might not be matching the current rate of the clock. In
such a case, let's read out the rate from the hardware and use that in
our set_rate instead.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
drivers/clk/clk.c | 6 +++++-
drivers/clk/clk_test.c | 28 ++++++++++++++++++++++++++++
2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 4ccf52d31a21..80eebf62d1f3 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2367,6 +2367,10 @@ static int clk_set_rate_range_nolock(struct clk *clk,
goto out;
}

+ rate = clk->core->req_rate;
+ if (clk->core->flags & CLK_GET_RATE_NOCACHE)
+ rate = clk_core_get_rate_recalc(clk->core);
+
/*
* Since the boundaries have been changed, let's give the
* opportunity to the provider to adjust the clock rate based on
@@ -2384,7 +2388,7 @@ static int clk_set_rate_range_nolock(struct clk *clk,
* - the determine_rate() callback does not really check for
* this corner case when determining the rate
*/
- rate = clamp(clk->core->req_rate, min, max);
+ rate = clamp(rate, min, max);
ret = clk_core_set_rate_nolock(clk->core, rate);
if (ret) {
/* rollback the changes */
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index f51a9ec3e452..70fee35c43c6 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -362,9 +362,37 @@ static void clk_test_uncached_set_range(struct kunit *test)
KUNIT_EXPECT_LE(test, rate, DUMMY_CLOCK_RATE_2);
}

+/*
+ * Test that for an uncached clock, clk_set_rate_range() will work
+ * properly if the rate has changed in hardware.
+ *
+ * In this case, it means that if the rate wasn't initially in the range
+ * we're trying to set, but got changed at some point into the range
+ * without the kernel knowing about it, its rate shouldn't be affected.
+ */
+static void clk_test_uncached_updated_rate_set_range(struct kunit *test)
+{
+ struct clk_dummy_context *ctx = test->priv;
+ struct clk_hw *hw = &ctx->hw;
+ struct clk *clk = hw->clk;
+ unsigned long rate;
+
+ ctx->rate = DUMMY_CLOCK_RATE_1 + 1000;
+ KUNIT_ASSERT_EQ(test,
+ clk_set_rate_range(clk,
+ DUMMY_CLOCK_RATE_1,
+ DUMMY_CLOCK_RATE_2),
+ 0);
+
+ rate = clk_get_rate(clk);
+ KUNIT_ASSERT_GT(test, rate, 0);
+ KUNIT_EXPECT_EQ(test, rate, DUMMY_CLOCK_RATE_1 + 1000);
+}
+
static struct kunit_case clk_uncached_test_cases[] = {
KUNIT_CASE(clk_test_uncached_get_rate),
KUNIT_CASE(clk_test_uncached_set_range),
+ KUNIT_CASE(clk_test_uncached_updated_rate_set_range),
{}
};

--
2.35.1