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    SubjectRe: [RFC PATCH 02/10] clockevents/drivers: add MPS2 Timer driver
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    On 11/25/2015 03:51 PM, Vladimir Murzin wrote:
    > 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).
    >
    >>> +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?

    Yes, that would be fine, but if it does never happen, we don't really
    need this check. If you prefer to make sure there isn't a spurious
    interrupt and considering it shouldn't happen, a pr_info trace may help
    to spot this misbehavior.

    >>> +}
    >>> +
    >>> +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;
    > }
    > }
    > }

    Yes.

    I don't like to have a "CLOCKSOURCE_OF_DECLARE" to initialize a
    clockevent but I can't blame you, this is what is done in the other drivers.

    >>> +}
    >>> +
    >>> +CLOCKSOURCE_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);
    >>>
    >>
    >>
    >


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