[v2] clk: sunxi-ng: ccu_common: Use readl_relaxed_poll_timeout_atomic for PLL lock
Commit Message
The Allwinner sunxi-ng CCU driver currently uses
readl_relaxed_poll_timeout() in ccu_helper_wait_for_lock() to wait for
PLLs to lock.
This non-atomic poll macro relies on ktime_get() and the kernel
timekeeping infrastructure. During early boot or sensitive clock
transitions (such as CPUfreq DVFS scaling) where timer interrupts or
timekeeping may be suspended or unstable, ktime_get() fails to advance.
This turns the timeout calculation into an infinite busy-wait loop,
causing RCU stalls and system freezes if the PLL lock bit does not
assert immediately.
Switch to readl_relaxed_poll_timeout_atomic(). This atomic variant relies
on udelay() rather than timekeeping, making it safe to execute even when
timekeeping is suspended or uninitialized.
Assisted-by: LLM
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
Notes:
v2:
- Replace custom udelay loop with readl_relaxed_poll_timeout_atomic()
as suggested by review.
Tested on Allwinner H618 (Mellow Fly-C5) and H616 boards in Armbian, resolving intermittent boot freezes and CPUfreq DVFS scaling lockups when timekeeping interrupts were suspended.
drivers/clk/sunxi-ng/ccu_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
@@ -35,7 +35,7 @@ void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
else
addr = common->base + common->reg;
- WARN_ON(readl_relaxed_poll_timeout(addr, reg, reg & lock, 100, 70000));
+ WARN_ON(readl_relaxed_poll_timeout_atomic(addr, reg, reg & lock, 100, 70000));
}
EXPORT_SYMBOL_NS_GPL(ccu_helper_wait_for_lock, "SUNXI_CCU");