clk: Take into account uncached clocks in clk_set_rate_range()

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.

Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com> # imx8mp
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> # exynos4210, meson g12b
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220816112530.1837489-13-maxime@cerno.tech
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index ceed49c5a88b..d3e121f21ae2 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -375,9 +375,40 @@ static void clk_test_uncached_set_range(struct kunit *test)
 	clk_put(clk);
 }
 
+/*
+ * 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 = clk_hw_get_clk(hw, NULL);
+	unsigned long rate;
+
+	/* We change the rate behind the clock framework's back */
+	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);
+
+	clk_put(clk);
+}
+
 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),
 	{}
 };