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author | Maxime Ripard <maxime@cerno.tech> | 2022-08-16 13:25:18 +0200 |
---|---|---|
committer | Stephen Boyd <sboyd@kernel.org> | 2022-09-15 09:31:09 -0700 |
commit | cb1b1dd96241f37ea41d241946d5153c48141cd5 (patch) | |
tree | a13346389da096ba710c88177b752a416bdd9e2f /drivers | |
parent | 3afb07231d603d51dca6a5d5e16d9d8f422f9b5f (diff) | |
download | linux-stable-cb1b1dd96241f37ea41d241946d5153c48141cd5.tar.gz linux-stable-cb1b1dd96241f37ea41d241946d5153c48141cd5.tar.bz2 linux-stable-cb1b1dd96241f37ea41d241946d5153c48141cd5.zip |
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 <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>
Link: https://lore.kernel.org/r/20220816112530.1837489-14-maxime@cerno.tech
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/clk/clk.c | 22 | ||||
-rw-r--r-- | drivers/clk/clk_test.c | 239 |
2 files changed, 261 insertions, 0 deletions
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 53b28e63deae..91bb1ea0e147 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1765,6 +1765,23 @@ 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; @@ -1834,6 +1851,8 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *core, clk_reparent(core, parent); clk_enable_unlock(flags); + clk_core_update_orphan_child_rates(core); + return old_parent; } @@ -1878,6 +1897,8 @@ static int __clk_set_parent(struct clk_core *core, struct clk_core *parent, flags = clk_enable_lock(); clk_reparent(core, old_parent); clk_enable_unlock(flags); + + clk_core_update_orphan_child_rates(core); __clk_set_parent_after(core, old_parent, parent); return ret; @@ -2506,6 +2527,7 @@ static void clk_core_reparent(struct clk_core *core, struct clk_core *new_parent) { clk_reparent(core, new_parent); + clk_core_update_orphan_child_rates(core); __clk_recalc_accuracies(core); __clk_recalc_rates(core, POST_RATE_CHANGE); } 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 @@ -596,6 +596,41 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent(struct kunit *test) /* * 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. */ static void @@ -627,6 +662,39 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent_get_rate(struct kunit /* * 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 * its rate is out of range. */ @@ -659,6 +727,43 @@ clk_test_orphan_transparent_multiple_parent_mux_set_parent_set_range_modified(st } /* + * 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 * account when rounding a rate. @@ -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, |