In certain cases it is possible that the timekeeping has been suspended
already when attempting to disable/enable a clkctrl clock. This will
happen at least on am43xx platform when attempting to enable / disable
the clockevent source itself, burping out a warning from timekeeping core.
The sequence of events leading to this:
-> timekeeping_suspend()
-> clockevents_suspend()
-> omap_clkevt_idle()
-> omap_hwmod_idle()
-> _omap4_clkctrl_clk_disable()
-> _omap4_is_timeout()
Avoid the issue by checking if the timekeeping is suspended and using
the fallback udelay approach for checking timeouts.
Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
---
drivers/clk/ti/clkctrl.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/ti/clkctrl.c b/drivers/clk/ti/clkctrl.c
index 284ba449..38dbcc1 100644
--- a/drivers/clk/ti/clkctrl.c
+++ b/drivers/clk/ti/clkctrl.c
@@ -21,6 +21,7 @@
#include <linux/of_address.h>
#include <linux/clk/ti.h>
#include <linux/delay.h>
+#include <linux/timekeeping.h>
#include "clock.h"
#define NO_IDLEST 0x1
@@ -90,7 +91,18 @@ static bool _omap4_is_ready(u32 val)
static bool _omap4_is_timeout(union omap4_timeout *time, u32 timeout)
{
- if (unlikely(_early_timeout)) {
+ /*
+ * There are two special cases where ktime_to_ns() can't be
+ * used to track the timeouts. First one is during early boot
+ * when the timers haven't been initialized yet. The second
+ * one is during suspend-resume cycle while timekeeping is
+ * being suspended / resumed. Clocksource for the system
+ * can be from a timer that requires pm_runtime access, which
+ * will eventually bring us here with timekeeping_suspended,
+ * during both suspend entry and resume paths. This happens
+ * at least on am43xx platform.
+ */
+ if (unlikely(_early_timeout || timekeeping_suspended)) {
if (time->cycles++ < timeout) {
udelay(1);
return false;
--
1.9.1
--
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