[PATCH 11/22] clk: Skip set_rate_range if our clock is orphan

Maxime Ripard
2022-04-08T09:14:07Z

clk_set_rate_range will now force a clk_set_rate() call to
core->req_rate. However, if our clock is orphan, req_rate will be 0 and
we will thus end up calling a set_rate to 0 on potentially all that
clock subtree.

This can be fairly invasive and result in poor decisions. In such a
case, let's just store the new range but bail out and skip the set_rate.

When that clock is no longer orphan though, we should be enforcing the
new range but we don't. Let's add a skipped test to make sure we don't
forget about that corner case.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
drivers/clk/clk.c | 6 +++++
drivers/clk/clk_test.c | 59 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 5b6ec11fcfcd..80fbec87309e 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2389,6 +2389,12 @@ static int clk_set_rate_range_nolock(struct clk *clk,
if (clk->core->flags & CLK_GET_RATE_NOCACHE)
rate = clk_core_get_rate_recalc(clk->core);

+ if (clk->core->orphan && !rate) {
+ pr_warn("%s: clk %s: Clock is orphan and doesn't have a rate!\n",
+ __func__, clk->core->name);
+ goto out;
+ }
+
/*
* Since the boundaries have been changed, let's give the
* opportunity to the provider to adjust the clock rate based on
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index fa6e32c460ac..0fffc70f9e2c 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -735,6 +735,26 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent_set_range_untouched(s
clk_put(parent);
}

+/*
+ * Test that, for a mux whose current parent hasn't been registered yet,
+ * calling clk_set_rate_range() will succeed but won't affect its rate.
+ */
+static void
+clk_test_orphan_transparent_multiple_parent_mux_set_range_get_rate(struct kunit *test)
+{
+ struct clk_multiple_parent_ctx *ctx = test->priv;
+ struct clk_hw *hw = &ctx->hw;
+ struct clk *clk = hw->clk;
+ unsigned long rate;
+ int ret;
+
+ ret = clk_set_rate_range(clk, DUMMY_CLOCK_RATE_1, DUMMY_CLOCK_RATE_2);
+ KUNIT_ASSERT_EQ(test, ret, 0);
+
+ rate = clk_get_rate(clk);
+ KUNIT_EXPECT_EQ(test, rate, 0);
+}
+
/*
* Test that, for a mux whose current parent hasn't been registered yet,
* calling clk_set_rate_range() will succeed, and will be taken into
@@ -758,6 +778,43 @@ clk_test_orphan_transparent_multiple_parent_mux_set_range_round_rate(struct kuni
KUNIT_EXPECT_LE(test, rate, DUMMY_CLOCK_RATE_2);
}

+/*
+ * Test that, for a mux that started orphan, was assigned and rate and
+ * then got switched to a valid parent, its rate is eventually within
+ * range.
+ *
+ * FIXME: Even though we update the rate as part of clk_set_parent(), we
+ * don't evaluate whether that new rate is within range and needs to be
+ * adjusted.
+ */
+static void
+clk_test_orphan_transparent_multiple_parent_mux_set_range_set_parent_get_rate(struct kunit *test)
+{
+ struct clk_multiple_parent_ctx *ctx = test->priv;
+ struct clk_hw *hw = &ctx->hw;
+ struct clk *clk = hw->clk, *parent;
+ unsigned long rate;
+ int ret;
+
+ kunit_skip(test, "This needs to be fixed in the core.");
+
+ parent = clk_hw_get_clk(&ctx->parents_ctx[1].hw, NULL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+ ret = clk_set_rate_range(clk, DUMMY_CLOCK_RATE_1, DUMMY_CLOCK_RATE_2);
+ KUNIT_ASSERT_EQ(test, ret, 0);
+
+ ret = clk_set_parent(clk, parent);
+ KUNIT_ASSERT_EQ(test, ret, 0);
+
+ rate = clk_get_rate(clk);
+ KUNIT_ASSERT_GT(test, rate, 0);
+ KUNIT_EXPECT_GE(test, rate, DUMMY_CLOCK_RATE_1);
+ KUNIT_EXPECT_LE(test, rate, DUMMY_CLOCK_RATE_2);
+
+ clk_put(parent);
+}
+
static struct kunit_case clk_orphan_transparent_multiple_parent_mux_test_cases[] = {
KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_get_parent),
KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent),
@@ -766,7 +823,9 @@ static struct kunit_case clk_orphan_transparent_multiple_parent_mux_test_cases[]
KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent_put),
KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent_set_range_modified),
KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent_set_range_untouched),
+ KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_range_get_rate),
KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_range_round_rate),
+ KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_range_set_parent_get_rate),
{}
};

--
2.35.1