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authorAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-01-15 11:34:21 +0100
committerThomas Gleixner <tglx@linutronix.de>2016-01-15 11:40:44 +0100
commitf02b4b72d12cbae7020a959e2ed0410a464b4cc4 (patch)
treeccddb43e1f80b3e9cbb70ac3af4201b78cb63709 /drivers/clocksource
parent1f16f116b01c110db20ab808562c8b8bc3ee3d6e (diff)
downloadlinux-f02b4b72d12cbae7020a959e2ed0410a464b4cc4.tar.bz2
clockevents/tcb_clksrc: Prevent disabling an already disabled clock
clockevents_exchange_device is calling clockevents_shutdown() on the new clockenvents device but it may have never been enabled in the first place. This results in the tcb clock being disabled without being enabled first: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:680 clk_disable+0x28/0x34() Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 4.4.0+ #6 Hardware name: Atmel AT91SAM9 [<c000f2b8>] (unwind_backtrace) from [<c000d01c>] (show_stack+0x10/0x14) [<c000d01c>] (show_stack) from [<c00172f0>] (warn_slowpath_common+0x78/0xa0) [<c00172f0>] (warn_slowpath_common) from [<c00173a8>] (warn_slowpath_null+0x18/0x20) [<c00173a8>] (warn_slowpath_null) from [<c0361528>] (clk_disable+0x28/0x34) [<c0361528>] (clk_disable) from [<c034d560>] (tc_shutdown+0x38/0x4c) [<c034d560>] (tc_shutdown) from [<c0059ad4>] (clockevents_switch_state+0x38/0x6c) [<c0059ad4>] (clockevents_switch_state) from [<c0059b18>] (clockevents_shutdown+0x10/0x24) [<c0059b18>] (clockevents_shutdown) from [<c005a458>] (tick_check_new_device+0x84/0xac) [<c005a458>] (tick_check_new_device) from [<c0059660>] (clockevents_register_device+0x7c/0x108) [<c0059660>] (clockevents_register_device) from [<c06b5a68>] (tcb_clksrc_init+0x390/0x3e8) [<c06b5a68>] (tcb_clksrc_init) from [<c00097cc>] (do_one_initcall+0x114/0x1d4) [<c00097cc>] (do_one_initcall) from [<c069bd54>] (kernel_init_freeable+0xfc/0x1b8) [<c069bd54>] (kernel_init_freeable) from [<c04c3818>] (kernel_init+0x8/0xe0) [<c04c3818>] (kernel_init) from [<c000a410>] (ret_from_fork+0x14/0x24) ---[ end trace 0000000000000001 ]--- Check what state we were in before trying to disable the clock. Fixes: cf4541c101ea ("clockevents/drivers/tcb_clksrc: Migrate to new 'set-state' interface") Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Cc: Nicolas Ferre <nicolas.ferre@atmel.com> Cc: Boris Brezillon <boris.brezillon@free-electrons.com> Cc: linux-arm-kernel@lists.infradead.org Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1452854061-30370-1-git-send-email-alexandre.belloni@free-electrons.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/tcb_clksrc.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
index 6ee91401918e..4da2af9694a2 100644
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c
@@ -98,7 +98,8 @@ static int tc_shutdown(struct clock_event_device *d)
__raw_writel(0xff, regs + ATMEL_TC_REG(2, IDR));
__raw_writel(ATMEL_TC_CLKDIS, regs + ATMEL_TC_REG(2, CCR));
- clk_disable(tcd->clk);
+ if (!clockevent_state_detached(d))
+ clk_disable(tcd->clk);
return 0;
}