Commit 481f541c authored by Maxime Ripard's avatar Maxime Ripard Committed by Stephen Boyd
Browse files

clk: test: Test clk_set_rate_range on orphan mux 



A bug recently affected the Tegra30 where calling clk_set_rate_range()
on a clock would make it change its rate to the minimum.

This was due to the clock in question being a mux that was orphan at
registration, which lead to the clk_core req_rate being 0, and the
clk_set_rate_range() function then calling clk_set_rate() with req_rate,
effectively making that clock running at the minimum rate allowed, even
though the initial rate was within that range.

Make a test suite to create a mux initially orphan, and then make sure
that if our clock rate was initially within a given range, then
enforcing that range won't affect it.

Signed-off-by: default avatarMaxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220325161144.1901695-3-maxime@cerno.tech


Signed-off-by: default avatarStephen Boyd <sboyd@kernel.org>
parent 5f7e2af0

drivers/clk/clk_test.c

+105 −0
Original line number Diff line number Diff line
@@ -72,6 +72,19 @@ static int clk_dummy_set_rate(struct clk_hw *hw, 
	return 0;

}



static int clk_dummy_single_set_parent(struct clk_hw *hw, u8 index)

{

	if (index >= clk_hw_get_num_parents(hw))

		return -EINVAL;



	return 0;

}



static u8 clk_dummy_single_get_parent(struct clk_hw *hw)

{

	return 0;

}



static const struct clk_ops clk_dummy_rate_ops = {

	.recalc_rate = clk_dummy_recalc_rate,

	.determine_rate = clk_dummy_determine_rate,
@@ -90,6 +103,11 @@ static const struct clk_ops clk_dummy_minimize_rate_ops = { 
	.set_rate = clk_dummy_set_rate,

};



static const struct clk_ops clk_dummy_single_parent_ops = {

	.set_parent = clk_dummy_single_set_parent,

	.get_parent = clk_dummy_single_get_parent,

};



static int clk_test_init_with_ops(struct kunit *test, const struct clk_ops *ops)

{

	struct clk_dummy_context *ctx;
@@ -239,6 +257,92 @@ static struct kunit_suite clk_test_suite = { 
	.test_cases = clk_test_cases,

};



struct clk_single_parent_ctx {

	struct clk_dummy_context parent_ctx;

	struct clk_hw hw;

};



static int clk_orphan_transparent_single_parent_mux_test_init(struct kunit *test)

{

	struct clk_single_parent_ctx *ctx;

	struct clk_init_data init = { };

	const char * const parents[] = { "orphan_parent" };

	int ret;



	ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);

	if (!ctx)

		return -ENOMEM;

	test->priv = ctx;



	init.name = "test_orphan_dummy_parent";

	init.ops = &clk_dummy_single_parent_ops;

	init.parent_names = parents;

	init.num_parents = ARRAY_SIZE(parents);

	init.flags = CLK_SET_RATE_PARENT;

	ctx->hw.init = &init;



	ret = clk_hw_register(NULL, &ctx->hw);

	if (ret)

		return ret;



	memset(&init, 0, sizeof(init));

	init.name = "orphan_parent";

	init.ops = &clk_dummy_rate_ops;

	ctx->parent_ctx.hw.init = &init;

	ctx->parent_ctx.rate = DUMMY_CLOCK_INIT_RATE;



	ret = clk_hw_register(NULL, &ctx->parent_ctx.hw);

	if (ret)

		return ret;



	return 0;

}



static void clk_orphan_transparent_single_parent_mux_test_exit(struct kunit *test)

{

	struct clk_single_parent_ctx *ctx = test->priv;



	clk_hw_unregister(&ctx->hw);

	clk_hw_unregister(&ctx->parent_ctx.hw);

}



/*

 * Test that a mux-only clock, with an initial rate within a range,

 * will still have the same rate after the range has been enforced.

 */

static void clk_test_orphan_transparent_parent_mux_set_range(struct kunit *test)

{

	struct clk_single_parent_ctx *ctx = test->priv;

	struct clk_hw *hw = &ctx->hw;

	struct clk *clk = hw->clk;

	unsigned long rate, new_rate;



	rate = clk_get_rate(clk);

	KUNIT_ASSERT_GT(test, rate, 0);



	KUNIT_ASSERT_EQ(test,

			clk_set_rate_range(clk,

					   ctx->parent_ctx.rate - 1000,

					   ctx->parent_ctx.rate + 1000),

			0);



	new_rate = clk_get_rate(clk);

	KUNIT_ASSERT_GT(test, new_rate, 0);

	KUNIT_EXPECT_EQ(test, rate, new_rate);

}



static struct kunit_case clk_orphan_transparent_single_parent_mux_test_cases[] = {

	KUNIT_CASE(clk_test_orphan_transparent_parent_mux_set_range),

	{}

};



static struct kunit_suite clk_orphan_transparent_single_parent_test_suite = {

	.name = "clk-orphan-transparent-single-parent-test",

	.init = clk_orphan_transparent_single_parent_mux_test_init,

	.exit = clk_orphan_transparent_single_parent_mux_test_exit,

	.test_cases = clk_orphan_transparent_single_parent_mux_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
@@ -788,6 +892,7 @@ static struct kunit_suite clk_range_minimize_test_suite = { 


kunit_test_suites(

	&clk_test_suite,

	&clk_orphan_transparent_single_parent_test_suite,

	&clk_range_test_suite,

	&clk_range_maximize_test_suite,

	&clk_range_minimize_test_suite