From 6d969d963a86c88ca1d6dcbc25447e2937e833b1 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Sat, 2 Apr 2022 14:36:59 +0200 Subject: [PATCH] clk: Stop forwarding clk_rate_requests to the parent If the clock cannot modify its rate and has CLK_SET_RATE_PARENT, clk_mux_determine_rate_flags() and clk_core_round_rate_nolock() will call clk_core_round_rate_nolock() with its parent clock but use the request of the child node either directly (clk_core_round_rate_nolock()) or by copying it (clk_mux_determine_rate_flags()). Both cases are problematic since the parent will now have a request with the best parent fields of the child (so pointing to itself) and the boundaries of the child as well. clk_core_round_rate_nolock() is even worse since we would directly modify the caller structure if the parent was ever to modify its own parent or its parent rate, then returning to the caller a best parent that isn't a parent of the clock we just called clk_determine_rate() onto. Let's create a new function that will create a new request to forward to the parent, clk_core_forward_rate_req() and update the relevant call sites to that new function. Let's also add a test to make sure we avoid regressions there. Tested-by: Alexander Stein # imx8mp Tested-by: Marek Szyprowski # exynos4210, meson g12b Signed-off-by: Maxime Ripard --- drivers/clk/clk.c | 58 ++++++++++++-- drivers/clk/clk_test.c | 176 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 227 insertions(+), 7 deletions(-) --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -542,6 +542,10 @@ static bool mux_is_better_rate(unsigned return now <= rate && now > best; } +static void clk_core_init_rate_req(struct clk_core * const core, + struct clk_rate_request *req, + unsigned long rate); + static int clk_core_round_rate_nolock(struct clk_core *core, struct clk_rate_request *req); @@ -565,6 +569,24 @@ static bool clk_core_has_parent(struct c return false; } +static void +clk_core_forward_rate_req(struct clk_core * const core, + struct clk_core * const parent, + struct clk_rate_request * const old_req, + struct clk_rate_request *req) +{ + if (WARN_ON(!clk_core_has_parent(core, parent))) + return; + + clk_core_init_rate_req(parent, req, old_req->rate); + + if (req->min_rate < old_req->min_rate) + req->min_rate = old_req->min_rate; + + if (req->max_rate > old_req->max_rate) + req->max_rate = old_req->max_rate; +} + int clk_mux_determine_rate_flags(struct clk_hw *hw, struct clk_rate_request *req, unsigned long flags) @@ -572,17 +594,19 @@ int clk_mux_determine_rate_flags(struct struct clk_core *core = hw->core, *parent, *best_parent = NULL; int i, num_parents, ret; unsigned long best = 0; - struct clk_rate_request parent_req = *req; /* if NO_REPARENT flag set, pass through to current parent */ if (core->flags & CLK_SET_RATE_NO_REPARENT) { parent = core->parent; if (core->flags & CLK_SET_RATE_PARENT) { + struct clk_rate_request parent_req; + if (!parent) { req->rate = 0; return 0; } + clk_core_forward_rate_req(core, parent, req, &parent_req); ret = clk_core_round_rate_nolock(parent, &parent_req); if (ret) return ret; @@ -600,23 +624,29 @@ int clk_mux_determine_rate_flags(struct /* find the parent that can provide the fastest rate <= rate */ num_parents = core->num_parents; for (i = 0; i < num_parents; i++) { + unsigned long parent_rate; + parent = clk_core_get_parent_by_index(core, i); if (!parent) continue; if (core->flags & CLK_SET_RATE_PARENT) { - parent_req = *req; + struct clk_rate_request parent_req; + + clk_core_forward_rate_req(core, parent, req, &parent_req); ret = clk_core_round_rate_nolock(parent, &parent_req); if (ret) continue; + + parent_rate = parent_req.rate; } else { - parent_req.rate = clk_core_get_rate_nolock(parent); + parent_rate = clk_core_get_rate_nolock(parent); } - if (mux_is_better_rate(req->rate, parent_req.rate, + if (mux_is_better_rate(req->rate, parent_rate, best, flags)) { best_parent = parent; - best = parent_req.rate; + best = parent_rate; } } @@ -1449,6 +1479,8 @@ static bool clk_core_can_round(struct cl static int clk_core_round_rate_nolock(struct clk_core *core, struct clk_rate_request *req) { + int ret; + lockdep_assert_held(&prepare_lock); if (!core) { @@ -1458,8 +1490,20 @@ static int clk_core_round_rate_nolock(st if (clk_core_can_round(core)) return clk_core_determine_round_nolock(core, req); - else if (core->flags & CLK_SET_RATE_PARENT) - return clk_core_round_rate_nolock(core->parent, req); + + if (core->flags & CLK_SET_RATE_PARENT) { + struct clk_rate_request parent_req; + + clk_core_forward_rate_req(core, core->parent, req, &parent_req); + ret = clk_core_round_rate_nolock(core->parent, &parent_req); + if (ret) + return ret; + + req->best_parent_rate = parent_req.rate; + req->rate = parent_req.rate; + + return 0; + } req->rate = core->rate; return 0; --- a/drivers/clk/clk_test.c +++ b/drivers/clk/clk_test.c @@ -999,6 +999,34 @@ clk_test_single_parent_mux_set_range_dis /* * Test that for a clock that can't modify its rate and with a single + * parent, if we set a range on the parent and then call + * clk_round_rate(), the boundaries of the parent are taken into + * account. + */ +static void +clk_test_single_parent_mux_set_range_round_rate_parent_only(struct kunit *test) +{ + struct clk_single_parent_ctx *ctx = test->priv; + struct clk_hw *hw = &ctx->hw; + struct clk *clk = hw->clk; + struct clk *parent; + unsigned long rate; + int ret; + + parent = clk_get_parent(clk); + KUNIT_ASSERT_PTR_NE(test, parent, NULL); + + ret = clk_set_rate_range(parent, DUMMY_CLOCK_RATE_1, DUMMY_CLOCK_RATE_2); + KUNIT_ASSERT_EQ(test, ret, 0); + + rate = clk_round_rate(clk, DUMMY_CLOCK_RATE_1 - 1000); + KUNIT_ASSERT_GT(test, rate, 0); + KUNIT_EXPECT_GE(test, rate, DUMMY_CLOCK_RATE_1); + KUNIT_EXPECT_LE(test, rate, DUMMY_CLOCK_RATE_2); +} + +/* + * Test that for a clock that can't modify its rate and with a single * parent, if we set a range on the parent and a more restrictive one on * the child, and then call clk_round_rate(), the boundaries of the * two clocks are taken into account. @@ -1033,12 +1061,50 @@ clk_test_single_parent_mux_set_range_rou KUNIT_EXPECT_LE(test, rate, DUMMY_CLOCK_RATE_2 - 1000); } +/* + * Test that for a clock that can't modify its rate and with a single + * parent, if we set a range on the child and a more restrictive one on + * the parent, and then call clk_round_rate(), the boundaries of the + * two clocks are taken into account. + */ +static void +clk_test_single_parent_mux_set_range_round_rate_parent_smaller(struct kunit *test) +{ + struct clk_single_parent_ctx *ctx = test->priv; + struct clk_hw *hw = &ctx->hw; + struct clk *clk = hw->clk; + struct clk *parent; + unsigned long rate; + int ret; + + parent = clk_get_parent(clk); + KUNIT_ASSERT_PTR_NE(test, parent, NULL); + + ret = clk_set_rate_range(parent, DUMMY_CLOCK_RATE_1 + 1000, DUMMY_CLOCK_RATE_2 - 1000); + KUNIT_ASSERT_EQ(test, ret, 0); + + ret = clk_set_rate_range(clk, DUMMY_CLOCK_RATE_1, DUMMY_CLOCK_RATE_2); + KUNIT_ASSERT_EQ(test, ret, 0); + + rate = clk_round_rate(clk, DUMMY_CLOCK_RATE_1 - 1000); + KUNIT_ASSERT_GT(test, rate, 0); + KUNIT_EXPECT_GE(test, rate, DUMMY_CLOCK_RATE_1 + 1000); + KUNIT_EXPECT_LE(test, rate, DUMMY_CLOCK_RATE_2 - 1000); + + rate = clk_round_rate(clk, DUMMY_CLOCK_RATE_2 + 1000); + KUNIT_ASSERT_GT(test, rate, 0); + KUNIT_EXPECT_GE(test, rate, DUMMY_CLOCK_RATE_1 + 1000); + KUNIT_EXPECT_LE(test, rate, DUMMY_CLOCK_RATE_2 - 1000); +} + static struct kunit_case clk_single_parent_mux_test_cases[] = { KUNIT_CASE(clk_test_single_parent_mux_get_parent), KUNIT_CASE(clk_test_single_parent_mux_has_parent), KUNIT_CASE(clk_test_single_parent_mux_set_range_disjoint_child_last), KUNIT_CASE(clk_test_single_parent_mux_set_range_disjoint_parent_last), KUNIT_CASE(clk_test_single_parent_mux_set_range_round_rate_child_smaller), + KUNIT_CASE(clk_test_single_parent_mux_set_range_round_rate_parent_only), + KUNIT_CASE(clk_test_single_parent_mux_set_range_round_rate_parent_smaller), {} }; @@ -1945,7 +2011,117 @@ static struct kunit_suite clk_range_mini .test_cases = clk_range_minimize_test_cases, }; +struct clk_leaf_mux_ctx { + struct clk_multiple_parent_ctx mux_ctx; + struct clk_hw hw; +}; + +static int +clk_leaf_mux_set_rate_parent_test_init(struct kunit *test) +{ + struct clk_leaf_mux_ctx *ctx; + const char *top_parents[2] = { "parent-0", "parent-1" }; + int ret; + + ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + test->priv = ctx; + + ctx->mux_ctx.parents_ctx[0].hw.init = CLK_HW_INIT_NO_PARENT("parent-0", + &clk_dummy_rate_ops, + 0); + ctx->mux_ctx.parents_ctx[0].rate = DUMMY_CLOCK_RATE_1; + ret = clk_hw_register(NULL, &ctx->mux_ctx.parents_ctx[0].hw); + if (ret) + return ret; + + ctx->mux_ctx.parents_ctx[1].hw.init = CLK_HW_INIT_NO_PARENT("parent-1", + &clk_dummy_rate_ops, + 0); + ctx->mux_ctx.parents_ctx[1].rate = DUMMY_CLOCK_RATE_2; + ret = clk_hw_register(NULL, &ctx->mux_ctx.parents_ctx[1].hw); + if (ret) + return ret; + + ctx->mux_ctx.current_parent = 0; + ctx->mux_ctx.hw.init = CLK_HW_INIT_PARENTS("test-mux", top_parents, + &clk_multiple_parents_mux_ops, + 0); + ret = clk_hw_register(NULL, &ctx->mux_ctx.hw); + if (ret) + return ret; + + ctx->hw.init = CLK_HW_INIT_HW("test-clock", &ctx->mux_ctx.hw, + &clk_dummy_single_parent_ops, + CLK_SET_RATE_PARENT); + ret = clk_hw_register(NULL, &ctx->hw); + if (ret) + return ret; + + return 0; +} + +static void clk_leaf_mux_set_rate_parent_test_exit(struct kunit *test) +{ + struct clk_leaf_mux_ctx *ctx = test->priv; + + clk_hw_unregister(&ctx->hw); + clk_hw_unregister(&ctx->mux_ctx.hw); + clk_hw_unregister(&ctx->mux_ctx.parents_ctx[0].hw); + clk_hw_unregister(&ctx->mux_ctx.parents_ctx[1].hw); +} + +/* + * Test that, for a clock that will forward any rate request to its + * parent, the rate request structure returned by __clk_determine_rate + * is sane and will be what we expect. + */ +static void clk_leaf_mux_set_rate_parent_determine_rate(struct kunit *test) +{ + struct clk_leaf_mux_ctx *ctx = test->priv; + struct clk_hw *hw = &ctx->hw; + struct clk *clk = hw->clk; + struct clk_rate_request req; + unsigned long rate; + int ret; + + rate = clk_get_rate(clk); + KUNIT_ASSERT_EQ(test, rate, DUMMY_CLOCK_RATE_1); + + clk_hw_init_rate_request(hw, &req, DUMMY_CLOCK_RATE_2); + + ret = __clk_determine_rate(hw, &req); + KUNIT_ASSERT_EQ(test, ret, 0); + + KUNIT_EXPECT_EQ(test, req.rate, DUMMY_CLOCK_RATE_2); + KUNIT_EXPECT_EQ(test, req.best_parent_rate, DUMMY_CLOCK_RATE_2); + KUNIT_EXPECT_PTR_EQ(test, req.best_parent_hw, &ctx->mux_ctx.hw); +} + +static struct kunit_case clk_leaf_mux_set_rate_parent_test_cases[] = { + KUNIT_CASE(clk_leaf_mux_set_rate_parent_determine_rate), + {} +}; + +/* + * Test suite for a clock whose parent is a mux with multiple parents. + * The leaf clock has CLK_SET_RATE_PARENT, and will forward rate + * requests to the mux, which will then select which parent is the best + * fit for a given rate. + * + * These tests are supposed to exercise the behaviour of muxes, and the + * proper selection of parents. + */ +static struct kunit_suite clk_leaf_mux_set_rate_parent_test_suite = { + .name = "clk-leaf-mux-set-rate-parent", + .init = clk_leaf_mux_set_rate_parent_test_init, + .exit = clk_leaf_mux_set_rate_parent_test_exit, + .test_cases = clk_leaf_mux_set_rate_parent_test_cases, +}; + kunit_test_suites( + &clk_leaf_mux_set_rate_parent_test_suite, &clk_test_suite, &clk_multiple_parents_mux_test_suite, &clk_orphan_transparent_multiple_parent_mux_test_suite,