From cb1b1dd96241f37ea41d241946d5153c48141cd5 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 16 Aug 2022 13:25:18 +0200 Subject: 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. The natural solution to this would be to update core->rate and core->req_rate in clk_reparent() by calling clk_recalc(). However, this doesn't work in all cases. Indeed, clk_recalc() is called by __clk_set_parent_before(), __clk_set_parent() and clk_core_reparent(). Both __clk_set_parent_before() and __clk_set_parent will call clk_recalc() with the enable_lock taken through a call to clk_enable_lock(), the underlying locking primitive being a spinlock. clk_recalc() calls the backing driver .recalc_rate hook, and that implementation might sleep if the underlying device uses a bus with accesses that might sleep, such as i2c. In such a situation, we would end up sleeping while holding a spinlock, and thus in an atomic section. In order to work around this, we can move the core->rate and core->req_rate update to the clk_recalc() calling sites, after the enable_lock has been released if it was taken. The only situation that could still be problematic is the clk_core_reparent() -> clk_reparent() case that doesn't have any locking. clk_core_reparent() is itself called by clk_hw_reparent(), which is then called by 4 drivers: * clk-stm32mp1.c, stm32/clk-stm32-core.c and tegra/clk-tegra210-emc.c use it in their set_parent implementation. The set_parent hook is only called by __clk_set_parent() and clk_change_rate(), both of them calling it without the enable_lock taken. * clk/tegra/clk-tegra124-emc.c calls it as part of its set_rate implementation. set_rate is only called by clk_change_rate(), again without the enable_lock taken. In both cases we can't end up in a situation where the clk_hw_reparent() caller would hold a spinlock, so it seems like this is a good workaround. Let's also add some unit tests to make sure we cover the original bug. Tested-by: Alexander Stein # imx8mp Tested-by: Marek Szyprowski # exynos4210, meson g12b Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20220816112530.1837489-14-maxime@cerno.tech Tested-by: Linux Kernel Functional Testing Tested-by: Naresh Kamboju Signed-off-by: Stephen Boyd --- drivers/clk/clk_test.c | 239 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 239 insertions(+) (limited to 'drivers/clk/clk_test.c') diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c index d3e121f21ae2..d1b1372f7aaa 100644 --- a/drivers/clk/clk_test.c +++ b/drivers/clk/clk_test.c @@ -594,6 +594,41 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent(struct kunit *test) clk_put(clk); } +/* + * 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 = clk_hw_get_clk(hw, NULL); + struct 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); + clk_put(clk); +} + /* * 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. @@ -625,6 +660,39 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent_get_rate(struct kunit clk_put(clk); } +/* + * 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 @@ -658,6 +726,43 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent_set_range_modified(st clk_put(clk); } +/* + * 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 = clk_hw_get_clk(hw, NULL); + struct 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); + clk_put(clk); +} + /* * 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 @@ -724,8 +829,11 @@ clk_test_orphan_transparent_multiple_parent_mux_set_range_set_parent_get_rate(st 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), KUNIT_CASE(clk_test_orphan_transparent_multiple_parent_mux_set_range_set_parent_get_rate), {} @@ -1021,6 +1129,136 @@ 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 = clk_hw_get_clk(hw, NULL); + unsigned long rate; + + rate = clk_get_rate(clk); + KUNIT_EXPECT_EQ(test, rate, DUMMY_CLOCK_INIT_RATE); + + clk_put(clk); +} + +/* + * 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 = clk_hw_get_clk(hw, NULL); + 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); + + clk_put(clk); +} + +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 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 @@ -1729,6 +1967,7 @@ 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, -- cgit v1.2.3