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clk: sunxi-ng: ccu_common: Use readl_relaxed_poll_timeout_atomic for PLL lock

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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>
Link: https://patch.msgid.link/20260916042910.382744-1-alastair@d-silva.org
Signed-off-by: Chen-Yu Tsai <wens@kernel.org>
This commit is contained in:
Alastair D'Silva 2026-09-16 14:29:10 +10:00 committed by Chen-Yu Tsai
parent 1002cc9d60
commit 9ef62592b8
1 changed files with 1 additions and 1 deletions
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2
drivers/clk/sunxi-ng/ccu_common.c
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@ -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");