[openwrt/staging/blocktrron.git] /

From 6d969d963a86c88ca1d6dcbc25447e2937e833b1 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
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 <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      |  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;
                }
        }
 
@@ -1450,6 +1480,8 @@ 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) {
@@ -1459,8 +1491,20 @@ 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,