From: Maxime Ripard <maxime@cerno.tech>
To: linux-clk@vger.kernel.org,
Mike Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>
Cc: Yassine Oudjana <y.oudjana@protonmail.com>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
Tony Lindgren <tony@atomide.com>,
Neil Armstrong <narmstrong@baylibre.com>,
Alexander Stein <alexander.stein@ew.tq-group.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Jerome Brunet <jbrunet@baylibre.com>,
Maxime Ripard <maxime@cerno.tech>
Subject: [PATCH v5 17/28] clk: Move clk_core_init_rate_req() from clk_core_round_rate_nolock() to its caller
Date: Mon, 16 May 2022 15:25:16 +0200 [thread overview]
Message-ID: <20220516132527.328190-18-maxime@cerno.tech> (raw)
In-Reply-To: <20220516132527.328190-1-maxime@cerno.tech>
The clk_rate_request structure is used internally as an argument for
the clk_core_determine_round_nolock() and clk_core_round_rate_nolock().
In both cases, the clk_core_init_rate_req() function is used to
initialize the clk_rate_request structure.
However, the expectation on who gets to call that function is
inconsistent between those two functions. Indeed,
clk_core_determine_round_nolock() will assume the structure is properly
initialized and will just use it.
On the other hand, clk_core_round_rate_nolock() will call
clk_core_init_rate_req() itself, expecting the caller to have filled
only a minimal set of parameters (rate, min_rate and max_rate).
If we ignore the calling convention inconsistency, this leads to a
second inconsistency for drivers:
* If they get called by the framework through
clk_core_round_rate_nolock(), the rate, min_rate and max_rate
fields will be filled by the caller, and the best_parent_rate and
best_parent_hw fields will get filled by clk_core_init_rate_req().
* If they get called by a driver through __clk_determine_rate (and
thus clk_core_round_rate_nolock), only best_parent_rate and
best_parent_hw are being explicitly set by the framework. Even
though we can reasonably expect rate to be set, only one of the 6
in-tree users explicitly set min_rate and max_rate.
* If they get called by the framework through
clk_core_determine_round_nolock(), then we have two callpaths.
Either it will be called by clk_core_round_rate_nolock() itself, or
it will be called by clk_calc_new_rates(), which will properly
initialize rate, min_rate, max_rate itself, and best_parent_rate
and best_parent_hw through clk_core_init_rate_req().
Even though the first and third case seems equivalent, they aren't when
the clock has CLK_SET_RATE_PARENT. Indeed, in such a case
clk_core_round_rate_nolock() will call itself on the current parent
clock with the same clk_rate_request structure.
The clk_core_init_rate_req() function will then be called on the parent
clock, with the child clk_rate_request pointer and will fill the
best_parent_rate and best_parent_hw fields with the parent context.
When the whole recursion stops and the call returns, the initial caller
will end up with a clk_rate_request structure with some informations of
the child clock (rate, min_rate, max_rate) and some others of the last
clock up the tree whose child had CLK_SET_RATE_PARENT (best_parent_hw,
best_parent_rate).
In the most common case, best_parent_rate is going to be equal on all
the parent clocks so it's not a big deal. However, best_parent_hw is
going to point to a clock that never has been a valid parent for that
clock which is definitely confusing.
In order to fix the calling inconsistency, let's move the
clk_core_init_rate_req() calls to the callers, which will also help a
bit with the clk_core_round_rate_nolock() recursion.
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 | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index ad8fca2bdf27..e5ebcfcfe4eb 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1415,8 +1415,6 @@ static int clk_core_round_rate_nolock(struct clk_core *core,
return 0;
}
- clk_core_init_rate_req(core, req, req->rate);
-
if (clk_core_can_round(core))
return clk_core_determine_round_nolock(core, req);
else if (core->flags & CLK_SET_RATE_PARENT)
@@ -1464,8 +1462,8 @@ unsigned long clk_hw_round_rate(struct clk_hw *hw, unsigned long rate)
int ret;
struct clk_rate_request req;
+ clk_core_init_rate_req(hw->core, &req, rate);
clk_core_get_boundaries(hw->core, &req.min_rate, &req.max_rate);
- req.rate = rate;
ret = clk_core_round_rate_nolock(hw->core, &req);
if (ret)
@@ -1497,8 +1495,8 @@ long clk_round_rate(struct clk *clk, unsigned long rate)
if (clk->exclusive_count)
clk_core_rate_unprotect(clk->core);
+ clk_core_init_rate_req(clk->core, &req, rate);
clk_core_get_boundaries(clk->core, &req.min_rate, &req.max_rate);
- req.rate = rate;
ret = clk_core_round_rate_nolock(clk->core, &req);
@@ -2206,8 +2204,8 @@ static unsigned long clk_core_req_round_rate_nolock(struct clk_core *core,
if (cnt < 0)
return cnt;
+ clk_core_init_rate_req(core, &req, req_rate);
clk_core_get_boundaries(core, &req.min_rate, &req.max_rate);
- req.rate = req_rate;
ret = clk_core_round_rate_nolock(core, &req);
--
2.36.1
next prev parent reply other threads:[~2022-05-16 13:27 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-16 13:24 [PATCH v5 00/28] clk: More clock rate fixes and tests Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 01/28] clk: Drop the rate range on clk_put() Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 02/28] clk: Skip clamping when rounding if there's no boundaries Maxime Ripard
2022-06-27 23:21 ` Stephen Boyd
2022-06-28 8:58 ` Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 03/28] clk: Introduce clk_get_rate_range() Maxime Ripard
2022-06-27 23:23 ` Stephen Boyd
2022-05-16 13:25 ` [PATCH v5 04/28] drm/vc4: hdmi: Rework hdmi_enable_4kp60 detection Maxime Ripard
2022-06-27 23:31 ` Stephen Boyd
2022-06-28 9:47 ` Maxime Ripard
2022-06-29 8:48 ` Stephen Boyd
2022-06-29 9:29 ` Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 05/28] clk: Mention that .recalc_rate can return 0 on error Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 06/28] clk: Clarify clk_get_rate() expectations Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 07/28] clk: tests: Add test suites description Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 08/28] clk: tests: Add reference to the orphan mux bug report Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 09/28] clk: tests: Add tests for uncached clock Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 10/28] clk: tests: Add tests for single parent mux Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 11/28] clk: tests: Add tests for mux with multiple parents Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 12/28] clk: tests: Add some tests for orphan " Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 13/28] clk: Take into account uncached clocks in clk_set_rate_range() Maxime Ripard
2022-06-29 9:01 ` Stephen Boyd
2022-06-29 12:42 ` Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 14/28] clk: Fix clk_get_parent() documentation Maxime Ripard
2022-06-29 9:05 ` Stephen Boyd
2022-06-29 13:12 ` Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 15/28] clk: Set req_rate on reparenting Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 16/28] clk: Change clk_core_init_rate_req prototype Maxime Ripard
2022-05-16 13:25 ` Maxime Ripard [this message]
2022-05-16 13:25 ` [PATCH v5 18/28] clk: Introduce clk_hw_init_rate_request() Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 19/28] clk: Add our request boundaries in clk_core_init_rate_req Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 20/28] clk: Switch from __clk_determine_rate to clk_core_round_rate_nolock Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 21/28] clk: Introduce clk_core_has_parent() Maxime Ripard
2022-06-29 9:11 ` Stephen Boyd
2022-05-16 13:25 ` [PATCH v5 22/28] clk: Stop forwarding clk_rate_requests to the parent Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 23/28] clk: Zero the clk_rate_request structure Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 24/28] clk: Test the clock pointer in clk_hw_get_name() Maxime Ripard
2022-06-29 9:13 ` Stephen Boyd
2022-06-29 9:39 ` Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 25/28] clk: Introduce the clk_hw_get_rate_range function Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 26/28] clk: qcom: clk-rcg2: Take clock boundaries into consideration for gfx3d Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 27/28] clk: tests: Add some tests for clk_get_rate_range() Maxime Ripard
2022-05-16 13:25 ` [PATCH v5 28/28] clk: tests: Add missing test case for ranges Maxime Ripard
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