From: Lars-Peter Clausen <lars@metafoo.de>
To: Ge Gao <ggao@invensense.com>
Cc: Jonathan Cameron <jic23@kernel.org>, linux-iio@vger.kernel.org
Subject: Re: [PATCH] [V9] Invensense MPU6050 Device Driver.
Date: Tue, 05 Feb 2013 11:00:45 +0100 [thread overview]
Message-ID: <5110D84D.9030308@metafoo.de> (raw)
In-Reply-To: <4781ec0fc6f6eb18cc8470fabce3e2a6@mail.gmail.com>
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
next prev parent reply other threads:[~2013-02-05 10:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-02 0:26 [PATCH] [V9] Invensense MPU6050 Device Driver Ge GAO
2013-02-03 15:51 ` Jonathan Cameron
2013-02-04 18:46 ` Ge Gao
[not found] ` <2b0b8fba-fc2c-44fb-9512-d86e87b698c1@email.android.com>
2013-02-04 20:12 ` Lars-Peter Clausen
2013-02-05 1:28 ` Ge Gao
2013-02-05 10:00 ` Lars-Peter Clausen [this message]
2013-02-05 18:36 ` Ge Gao
2013-02-05 19:47 ` Lars-Peter Clausen
2013-02-06 3:41 ` Lars-Peter Clausen
2013-02-10 17:30 ` Lars-Peter Clausen
2013-02-10 17:45 ` Jonathan Cameron
2013-02-11 18:07 ` Ge Gao
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