Thread (20 messages) 20 messages, 4 authors, 2015-12-01

Re: [RFC PATCH 02/10] clockevents/drivers: add MPS2 Timer driver

From: Vladimir Murzin <hidden>
Date: 2015-11-25 14:51:14
Also in: linux-api, linux-arm-kernel, linux-serial, lkml

Hi Daniel,

Thanks for you review, I agree on all concerns raised and address them
in the next version. Just some points to confirm below (I left only
relevant parts).
quoted
+static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id)
+{
+    struct clockevent_mps2 *ce = dev_id;
+    u32 status = readl(ce->reg + TIMER_INT);
+
+    if (!status)
+        return IRQ_NONE;
Why that could happen ? Add a comment.
Sort of defensive programming, I never seen it happens, but just in case
of spurious interrupts... Do you prefer to get rid of this check or

    /* spurious interrupt? */
    if (!status)
        return IRQ_NONE;

would be fine to you?
quoted
+}
+
+static void __init mps2_timer_init(struct device_node *np)
+{
+    static int clksrc;
+
+    if (!clksrc && !mps2_clocksource_init(np))
+        clksrc = 1;
+    else
+        mps2_clockevents_init(np);
That assumes the clocksource is defined before the clockevents in the
DT. If it is not the case, the mps2_clocksource_init will fail (and spit
errors) and mps2_clockevents_init() won't be called.
Does following (stolen from efm32) look better to you?

static void __init mps2_timer_init(struct device_node *np)
{
	static int has_clocksource, has_clockevent;
	int ret;

	if (!has_clocksource) {
		ret = mps2_clocksource_init(np);
		if (!ret) {
			has_clocksource = 1;
			return;
		}
	}

	if (!has_clockevent) {
		ret = mps2_clockevent_init(np);
		if (!ret) {
			has_clockevent = 1;
			return;
		}
	}
}

Thanks
Vladimir
quoted
+}
+
+CLOCKSOURCE_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);
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