[PATCH] clk: Manage proper runtime PM state in clk_change_rate()
From: Ulf Hansson <hidden>
Date: 2017-11-30 13:24:49
Also in:
linux-clk, linux-pm, linux-samsung-soc
On 30 November 2017 at 13:14, Marek Szyprowski [off-list ref] wrote:
clk_change_rate() propagates rate change down to all its children. Such
operation requires managing proper runtime PM state of each child, what
was missing. Add needed calls to clk_pm_runtime*() to ensure that
set_rate() clock callback is called on runtime active clock.
This fixes following issue found on Exynos5433 TM2 board with devfreq
enabled:
Synchronous External Abort: synchronous external abort (0x96000210) at 0xffffff80093f5600
Internal error: : 96000210 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 5 Comm: kworker/u16:0 Not tainted 4.15.0-rc1-next-20171129+ #4
Hardware name: Samsung TM2 board (DT)
Workqueue: devfreq_wq devfreq_monitor
task: ffffffc0ca96b600 task.stack: ffffff80093a8000
pstate: a0000085 (NzCv daIf -PAN -UAO)
pc : clk_divider_set_rate+0x54/0x118
lr : clk_divider_set_rate+0x44/0x118
...
Process kworker/u16:0 (pid: 5, stack limit = 0xffffff80093a8000)
Call trace:
clk_divider_set_rate+0x54/0x118
clk_change_rate+0xfc/0x4e0
clk_change_rate+0x1f0/0x4e0
clk_change_rate+0x1f0/0x4e0
clk_change_rate+0x1f0/0x4e0
clk_core_set_rate_nolock+0x138/0x148
clk_set_rate+0x28/0x50
exynos_bus_passive_target+0x6c/0x11c
update_devfreq_passive+0x58/0xb4
devfreq_passive_notifier_call+0x50/0x5c
notifier_call_chain+0x4c/0x88
__srcu_notifier_call_chain+0x54/0x80
srcu_notifier_call_chain+0x14/0x1c
update_devfreq+0x100/0x1b4
devfreq_monitor+0x2c/0x88
process_one_work+0x148/0x3d8
worker_thread+0x13c/0x3f8
kthread+0x100/0x12c
ret_from_fork+0x10/0x18
Reported-by: Chanwoo Choi <cw00.choi@samsung.com>
Fixes: 9a34b45397e5 ("clk: Add support for runtime PM")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>Reviewed-by: Ulf Hansson <redacted> Kind regards Uffe
quoted hunk ↗ jump to hunk
--- For some unknown reason handling of this case was missing in the initial patch, which added runtime PM support for clock core. Even tests in linux-next did not revealed this issue. This patch finaly fixes it, as it is now easy to trigger it with v4.15-rc1. Best regards Marek Szyprowski Samsung R&D Institute Poland --- drivers/clk/clk.c | 5 +++++ 1 file changed, 5 insertions(+)diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 647d056df88c..8a1860a36c77 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c@@ -1564,6 +1564,9 @@ static void clk_change_rate(struct clk_core *core) best_parent_rate = core->parent->rate; } + if (clk_pm_runtime_get(core)) + return; + if (core->flags & CLK_SET_RATE_UNGATE) { unsigned long flags;@@ -1634,6 +1637,8 @@ static void clk_change_rate(struct clk_core *core) /* handle the new child who might not be in core->children yet */ if (core->new_child) clk_change_rate(core->new_child); + + clk_pm_runtime_put(core); } static int clk_core_set_rate_nolock(struct clk_core *core, --2.15.0