clk: Set req_rate on reparenting

If a non-rate clock started by default with a parent that never
registered, core->req_rate will be 0. The expectation is that whenever
the parent will be registered, req_rate will be updated with the new
value that has just been computed.

However, if that clock is a mux, clk_set_parent() can also make that
clock no longer orphan. In this case however, we never update req_rate.
Let's make sure it's the case for the newly unorphan clock and all its
children.

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

@@ -1774,6 +1774,23 @@ static void clk_core_update_orphan_status(struct clk_core *core, bool is_orphan)
 		clk_core_update_orphan_status(child, is_orphan);
 }
 
+/*
+ * Update the orphan rate and req_rate of @core and all its children.
+ */
+static void clk_core_update_orphan_child_rates(struct clk_core *core)
+{
+	struct clk_core *child;
+	unsigned long parent_rate = 0;
+
+	if (core->parent)
+		parent_rate = core->parent->rate;
+
+	core->rate = core->req_rate = clk_recalc(core, parent_rate);
+
+	hlist_for_each_entry(child, &core->children, child_node)
+		clk_core_update_orphan_child_rates(child);
+}
+
 static void clk_reparent(struct clk_core *core, struct clk_core *new_parent)
 {
 	bool was_orphan = core->orphan;
@@ -1798,6 +1815,7 @@ static void clk_reparent(struct clk_core *core, struct clk_core *new_parent)
 	}
 
 	core->parent = new_parent;
+	clk_core_update_orphan_child_rates(core);
 }
 
 static struct clk_core *__clk_set_parent_before(struct clk_core *core,

drivers/clk/clk_test.c

@@ -575,6 +575,39 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent(struct kunit *test)
 	clk_put(parent);
 }
 
+/*
+ * Test that, for a mux that started orphan but got switched to a valid
+ * parent, calling clk_drop_range() on the mux won't affect the parent
+ * rate.
+ */
+static void
+clk_test_orphan_transparent_multiple_parent_mux_set_parent_drop_range(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 parent_rate, new_parent_rate;
+	int ret;
+
+	parent = clk_hw_get_clk(&ctx->parents_ctx[1].hw, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+	parent_rate = clk_get_rate(parent);
+	KUNIT_ASSERT_GT(test, parent_rate, 0);
+
+	ret = clk_set_parent(clk, parent);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ret = clk_drop_range(clk);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	new_parent_rate = clk_get_rate(clk);
+	KUNIT_ASSERT_GT(test, new_parent_rate, 0);
+	KUNIT_EXPECT_EQ(test, parent_rate, new_parent_rate);
+
+	clk_put(parent);
+}
+
 /*
  * Test that, for a mux that started orphan but got switched to a valid
  * parent, the rate of the mux and its new parent are consistent.
@@ -603,6 +636,39 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent_get_rate(struct kunit
 	KUNIT_EXPECT_EQ(test, parent_rate, rate);
 }
 
+/*
+ * Test that, for a mux that started orphan but got switched to a valid
+ * parent, calling clk_put() on the mux won't affect the parent rate.
+ */
+static void
+clk_test_orphan_transparent_multiple_parent_mux_set_parent_put(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx = test->priv;
+	struct clk *clk, *parent;
+	unsigned long parent_rate, new_parent_rate;
+	int ret;
+
+	parent = clk_hw_get_clk(&ctx->parents_ctx[1].hw, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+	clk = clk_hw_get_clk(&ctx->hw, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, clk);
+
+	parent_rate = clk_get_rate(parent);
+	KUNIT_ASSERT_GT(test, parent_rate, 0);
+
+	ret = clk_set_parent(clk, parent);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	clk_put(clk);
+
+	new_parent_rate = clk_get_rate(parent);
+	KUNIT_ASSERT_GT(test, new_parent_rate, 0);
+	KUNIT_EXPECT_EQ(test, parent_rate, new_parent_rate);
+
+	clk_put(parent);
+}
+
 /*
  * Test that, for a mux that started orphan but got switched to a valid
  * parent, calling clk_set_rate_range() will affect the parent state if
@@ -634,6 +700,41 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent_set_range_modified(st
 	clk_put(parent);
 }
 
+/*
+ * Test that, for a mux that started orphan but got switched to a valid
+ * parent, calling clk_set_rate_range() won't affect the parent state if
+ * its rate is within range.
+ */
+static void
+clk_test_orphan_transparent_multiple_parent_mux_set_parent_set_range_untouched(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 parent_rate, new_parent_rate;
+	int ret;
+
+	parent = clk_hw_get_clk(&ctx->parents_ctx[1].hw, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+	parent_rate = clk_get_rate(parent);
+	KUNIT_ASSERT_GT(test, parent_rate, 0);
+
+	ret = clk_set_parent(clk, parent);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ret = clk_set_rate_range(clk,
+				 DUMMY_CLOCK_INIT_RATE - 1000,
+				 DUMMY_CLOCK_INIT_RATE + 1000);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	new_parent_rate = clk_get_rate(parent);
+	KUNIT_ASSERT_GT(test, new_parent_rate, 0);
+	KUNIT_EXPECT_EQ(test, parent_rate, new_parent_rate);
+
+	clk_put(parent);
+}
+
 /*
  * 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
@@ -660,8 +761,11 @@ clk_test_orphan_transparent_multiple_parent_mux_set_range_round_rate(struct kuni
 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),
+	KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent_drop_range),
 	KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_parent_get_rate),
+	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_round_rate),
 	{}
 };
@@ -946,6 +1050,132 @@ static struct kunit_suite clk_orphan_transparent_single_parent_test_suite = {
 	.test_cases = clk_orphan_transparent_single_parent_mux_test_cases,
 };
 
+struct clk_single_parent_two_lvl_ctx {
+	struct clk_dummy_context parent_parent_ctx;
+	struct clk_dummy_context parent_ctx;
+	struct clk_hw hw;
+};
+
+static int
+clk_orphan_two_level_root_last_test_init(struct kunit *test)
+{
+	struct clk_single_parent_two_lvl_ctx *ctx;
+	int ret;
+
+	ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+	test->priv = ctx;
+
+	ctx->parent_ctx.hw.init =
+		CLK_HW_INIT("intermediate-parent",
+			    "root-parent",
+			    &clk_dummy_single_parent_ops,
+			    CLK_SET_RATE_PARENT);
+	ret = clk_hw_register(NULL, &ctx->parent_ctx.hw);
+	if (ret)
+		return ret;
+
+	ctx->hw.init =
+		CLK_HW_INIT("test-clk", "intermediate-parent",
+			    &clk_dummy_single_parent_ops,
+			    CLK_SET_RATE_PARENT);
+	ret = clk_hw_register(NULL, &ctx->hw);
+	if (ret)
+		return ret;
+
+	ctx->parent_parent_ctx.rate = DUMMY_CLOCK_INIT_RATE;
+	ctx->parent_parent_ctx.hw.init =
+		CLK_HW_INIT_NO_PARENT("root-parent",
+				      &clk_dummy_rate_ops,
+				      0);
+	ret = clk_hw_register(NULL, &ctx->parent_parent_ctx.hw);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void
+clk_orphan_two_level_root_last_test_exit(struct kunit *test)
+{
+	struct clk_single_parent_two_lvl_ctx *ctx = test->priv;
+
+	clk_hw_unregister(&ctx->hw);
+	clk_hw_unregister(&ctx->parent_ctx.hw);
+	clk_hw_unregister(&ctx->parent_parent_ctx.hw);
+}
+
+/*
+ * Test that, for a clock whose parent used to be orphan, clk_get_rate()
+ * will return the proper rate.
+ */
+static void
+clk_orphan_two_level_root_last_test_get_rate(struct kunit *test)
+{
+	struct clk_single_parent_two_lvl_ctx *ctx = test->priv;
+	struct clk_hw *hw = &ctx->hw;
+	struct clk *clk = hw->clk;
+	unsigned long rate;
+
+	rate = clk_get_rate(clk);
+	KUNIT_EXPECT_EQ(test, rate, DUMMY_CLOCK_INIT_RATE);
+}
+
+/*
+ * Test that, for a clock whose parent used to be orphan,
+ * clk_set_rate_range() won't affect its rate if it is already within
+ * range.
+ *
+ * See (for Exynos 4210):
+ * https://lore.kernel.org/linux-clk/366a0232-bb4a-c357-6aa8-636e398e05eb@samsung.com/
+ */
+static void
+clk_orphan_two_level_root_last_test_set_range(struct kunit *test)
+{
+	struct clk_single_parent_two_lvl_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_INIT_RATE - 1000,
+				 DUMMY_CLOCK_INIT_RATE + 1000);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	rate = clk_get_rate(clk);
+	KUNIT_ASSERT_GT(test, rate, 0);
+	KUNIT_EXPECT_EQ(test, rate, DUMMY_CLOCK_INIT_RATE);
+}
+
+static struct kunit_case
+clk_orphan_two_level_root_last_test_cases[] = {
+	KUNIT_CASE(clk_orphan_two_level_root_last_test_get_rate),
+	KUNIT_CASE(clk_orphan_two_level_root_last_test_set_range),
+	{}
+};
+
+/*
+ * Test suite for a basic, transparent, clock with a parent that is also
+ * such a clock. The parent's parent is registered last, while the
+ * parent and its child are registered in that order. The intermediate
+ * and leaf clocks will thus be orphan when registered, but the leaf
+ * clock itself will always have its parent and will never be
+ * reparented. Indeed, it's only orphan because its parent is.
+ *
+ * These tests are supposed to exercise the behaviour of the consumer
+ * API when dealing with an orphan clock, and how we deal with the
+ * transition to a valid parent.
+ */
+static struct kunit_suite
+clk_orphan_two_level_root_last_test_suite = {
+	.name = "clk-orphan-two-level-root-last-test",
+	.init = clk_orphan_two_level_root_last_test_init,
+	.exit = clk_orphan_two_level_root_last_test_exit,
+	.test_cases = clk_orphan_two_level_root_last_test_cases,
+};
+
 /*
  * Test that clk_set_rate_range won't return an error for a valid range
  * and that it will make sure the rate of the clock is within the
@@ -1629,6 +1859,7 @@ kunit_test_suites(
 	&clk_multiple_parents_mux_test_suite,
 	&clk_orphan_transparent_multiple_parent_mux_test_suite,
 	&clk_orphan_transparent_single_parent_test_suite,
+	&clk_orphan_two_level_root_last_test_suite,
 	&clk_range_test_suite,
 	&clk_range_maximize_test_suite,
 	&clk_range_minimize_test_suite,