Hi Martin,
Have you enabled/setup any Kernel Preemption?
Chris
On 4 April 2018 at 22:50, Martin Kelly <mke...@xevo.com> wrote:
> Hi,
>
> I've noticed strange behavior on my H3 (nanopi neo air) and am wondering if
> anyone has suggestions for further debugging it, as I'm getting stumped.
>
> Specifically, I have configured a device (Invensense MPU9250) to deliver
> interrupts at 10Hz to PG_EINT11. For some reason, though, the interrupt
> handler is being called at only about 6 Hz.
>
> Looking at a logic analyzer, I see the hardware is interrupting at 10 Hz as
> it should, but sometimes the interrupts are just missed from the kernel
> side. So you might see a 200 ms gap between calls to the IRQ handler, but
> 100 ms between hardware IRQ events.
>
> Using ftrace, I see that sunxi_pinctrl_irq_handler is being called at about
> 6 Hz as well. The system load is very low (~0%) on all CPUs, and it doesn't
> appear that anyone is disabling this interrupt.
>
> I have also verified that the IRQ handlers are exiting in less than 1 ms,
> and the bottom half of the handler in less than 5 ms; they don't appear to
> be conflicting with the next IRQ coming in.
>
> The interrupts are rising edges, and are consistently about 50 microseconds
> in width.
>
> This is the relevant device-tree fragment:
>
> &i2c0 {
> mpu9250@68 {
> model = "Invensense MPU9250";
> compatible = "invensense,mpu9250";
> reg = <0x68>;
> interrupt-parent = <&pio>;
> interrupts = <6 11 IRQ_TYPE_EDGE_RISING>; /* PG11 /
> PG_EINT11 */
> };
> };
>
> I'm quite stumped as to where to look next and would welcome any
> suggestions.
>
> Thanks,
> Martin
>
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