From f02b4b72d12cbae7020a959e2ed0410a464b4cc4 Mon Sep 17 00:00:00 2001 From: Alexandre Belloni Date: Fri, 15 Jan 2016 11:34:21 +0100 Subject: 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 [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (warn_slowpath_common+0x78/0xa0) [] (warn_slowpath_common) from [] (warn_slowpath_null+0x18/0x20) [] (warn_slowpath_null) from [] (clk_disable+0x28/0x34) [] (clk_disable) from [] (tc_shutdown+0x38/0x4c) [] (tc_shutdown) from [] (clockevents_switch_state+0x38/0x6c) [] (clockevents_switch_state) from [] (clockevents_shutdown+0x10/0x24) [] (clockevents_shutdown) from [] (tick_check_new_device+0x84/0xac) [] (tick_check_new_device) from [] (clockevents_register_device+0x7c/0x108) [] (clockevents_register_device) from [] (tcb_clksrc_init+0x390/0x3e8) [] (tcb_clksrc_init) from [] (do_one_initcall+0x114/0x1d4) [] (do_one_initcall) from [] (kernel_init_freeable+0xfc/0x1b8) [] (kernel_init_freeable) from [] (kernel_init+0x8/0xe0) [] (kernel_init) from [] (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 Cc: Nicolas Ferre Cc: Boris Brezillon Cc: linux-arm-kernel@lists.infradead.org Cc: Daniel Lezcano 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 --- drivers/clocksource/tcb_clksrc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/clocksource/tcb_clksrc.c') 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; } -- cgit v1.2.3