Re: [PATCH 6/7] clocksource: Add Pistachio clocksource-only driver

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On Thu, 21 May 2015, Ezequiel Garcia wrote:
> +static cycle_t clocksource_read_cycles(struct clocksource *cs)
> +{
> +	u32 counter, overflw;
> +	unsigned long flags;
> +
> +	raw_spin_lock_irqsave(&lock, flags);

Hmm. Is that lock really necessary to read that counter? The
clocksource is global. And if its actually used for timekeeping, the
lock can get heavy contended.

> +	overflw = gpt_readl(TIMER_CURRENT_OVERFLOW_VALUE, 0);
> +	counter = gpt_readl(TIMER_CURRENT_VALUE, 0);
> +	raw_spin_unlock_irqrestore(&lock, flags);
> +
> +	return ~(cycle_t)counter;
> +}

Thanks,

	tglx
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]
  Powered by Linux