From 588fb54b0cc5be5fd2e12bb04810534ffc3d49cc Mon Sep 17 00:00:00 2001 From: Marek Szyprowski Date: Thu, 30 Nov 2017 13:14:51 +0100 Subject: [PATCH 1/2] clk: Manage proper runtime PM state in clk_change_rate() 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 Fixes: 9a34b45397e5 ("clk: Add support for runtime PM") Signed-off-by: Marek Szyprowski Reviewed-by: Ulf Hansson Tested-by: Chanwoo Choi Reviewed-by: Chanwoo Choi Signed-off-by: Stephen Boyd --- 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, From 975b820b6836b6b6c42fb84cd2e772e2b41bca67 Mon Sep 17 00:00:00 2001 From: Cai Li Date: Tue, 21 Nov 2017 17:24:38 +0800 Subject: [PATCH 2/2] clk: fix a panic error caused by accessing NULL pointer In some cases the clock parent would be set NULL when doing re-parent, it will cause a NULL pointer accessing if clk_set trace event is enabled. This patch sets the parent as "none" if the input parameter is NULL. Fixes: dfc202ead312 (clk: Add tracepoints for hardware operations) Signed-off-by: Cai Li Signed-off-by: Chunyan Zhang Signed-off-by: Stephen Boyd --- include/trace/events/clk.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/trace/events/clk.h b/include/trace/events/clk.h index 758607226bfd..2cd449328aee 100644 --- a/include/trace/events/clk.h +++ b/include/trace/events/clk.h @@ -134,12 +134,12 @@ DECLARE_EVENT_CLASS(clk_parent, TP_STRUCT__entry( __string( name, core->name ) - __string( pname, parent->name ) + __string( pname, parent ? parent->name : "none" ) ), TP_fast_assign( __assign_str(name, core->name); - __assign_str(pname, parent->name); + __assign_str(pname, parent ? parent->name : "none"); ), TP_printk("%s %s", __get_str(name), __get_str(pname))