From 655e66b0add0aba16e84587dbb939f8ddce612b0 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Fri, 1 Apr 2022 15:27:09 +0200
Subject: [PATCH] clk: Skip set_rate_range if our clock is orphan

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.

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>
---
 drivers/clk/clk.c      |  6 +++++
 drivers/clk/clk_test.c | 59 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+)

--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2388,6 +2388,12 @@ static int clk_set_rate_range_nolock(str
 	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
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -737,6 +737,26 @@ clk_test_orphan_transparent_multiple_par
 
 /*
  * 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
  * account when rounding a rate.
  */
@@ -758,6 +778,43 @@ clk_test_orphan_transparent_multiple_par
 	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_tran
 	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),
 	{}
 };
 
