On 02/05/2013 02:28 AM, Ge Gao wrote: > Dear Lars and Jonanthan, > I have one question regarding the timestamp inside IRQ. I found that the > timestamp taken during IRQ is not accurate and it varies a lot. I can see > the hardware interrupt came in a regular pace while the timestamp taken > varies violently(up to 50% or more). It seems that it is because the data > cache that stores the timestamp(xtime) is not updated when there is > interrupt. So it actually takes the wrong timestamp. I searched online and > didn't find any useful ideas. I think taking timestamp during IRQ is a > common practice. Is there any existing solution for this or did I do > anything wrong? The code in the current patch is inv_mpu6050_irq_handler() > of inv_mpu_ring.c. Thanks. What kind of time variation are we talking about? nanosecons, microseconds, milliseconds? iio_get_time_ns should query the systems clockchip and so the result should be pretty precise. - Lars -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
