From: "Zubair Lutfullah :" <zubair.lutfullah@gmail.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Zubair Lutfullah <zubair.lutfullah@gmail.com>,
jic23@cam.ac.uk, dmitry.torokhov@gmail.com,
linux-iio@vger.kernel.org, linux-input@vger.kernel.org,
linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org,
Russ.Dill@ti.com
Subject: Re: [PATCH 4/4] iio: ti_am335x_adc: Add continuous sampling and trigger support
Date: Fri, 16 Aug 2013 22:13:29 +0100 [thread overview]
Message-ID: <20130816211312.GB2528@gmail.com> (raw)
In-Reply-To: <20130816132549.GD1263@linutronix.de>
On Fri, Aug 16, 2013 at 03:25:49PM +0200, Sebastian Andrzej Siewior wrote:
> * Zubair Lutfullah | 2013-08-13 21:05:03 [+0100]:
>
> >diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
> >index 3ceac3e..0d7e313 100644
> >--- a/drivers/iio/adc/ti_am335x_adc.c
> >+++ b/drivers/iio/adc/ti_am335x_adc.c
> >@@ -141,58 +350,51 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
> > {
> …
> >+ if (iio_buffer_enabled(indio_dev))
> >+ return -EBUSY;
> >+ else {
>
> You can drop else so you lose one ident level.
>
Noted.
> >+ unsigned long timeout = jiffies + usecs_to_jiffies
> >+ (IDLE_TIMEOUT * adc_dev->channels);
>
> What computing this once? ->channels is assigned at probe time.
>
The timeout depends on number of SW enabled channels.
Hence the calculation. In this read_raw, one channel is to be
read.
However, all channels are sampled. And the one that the
userspace requires is pushed to user.
> >+ /* Wait for ADC sequencer to complete sampling */
> >+ while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) {
> >+ if (time_after(jiffies, timeout))
> >+ return -EAGAIN;
>
> You should check the condition after the timeout occured once again. It
> is possible that the task performing the read has been pushed away by a
> higher prio task (or preempted incase this sounds like a bully) and
> after it got back on the cpu the timeout occured but the condition is
> valid and no reason for -EAGAIN.
>
> Sebastian
Interesting catch. I'll look into it.
Thanks for pointing it out.
Zubair
next prev parent reply other threads:[~2013-08-16 22:18 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-13 20:04 [PATCH 0/4] iio: input: ti_am335x_adc: Add continuous sampling support round 5 Zubair Lutfullah
2013-08-13 20:05 ` [PATCH 1/4] input: ti_am335x_tsc: correct step mask update after IRQ Zubair Lutfullah
2013-08-13 20:05 ` Zubair Lutfullah
2013-08-13 20:05 ` [PATCH 2/4] input: ti_am335x_tsc: Increase sequencer delay time Zubair Lutfullah
2013-08-13 20:05 ` [PATCH 3/4] input: ti_am335x_tsc: Enable shared IRQ for TSC, add overrun and underflow checks Zubair Lutfullah
2013-08-13 20:05 ` Zubair Lutfullah
2013-08-13 20:05 ` [PATCH 4/4] iio: ti_am335x_adc: Add continuous sampling and trigger support Zubair Lutfullah
2013-08-15 11:43 ` Jonathan Cameron
2013-08-15 11:43 ` Jonathan Cameron
2013-08-16 10:07 ` Sebastian Andrzej Siewior
2013-08-16 10:07 ` Sebastian Andrzej Siewior
2013-08-16 10:17 ` Sebastian Andrzej Siewior
2013-08-16 10:17 ` Sebastian Andrzej Siewior
2013-08-16 11:33 ` Jonathan Cameron
2013-08-16 11:33 ` Jonathan Cameron
2013-08-16 10:46 ` Sebastian Andrzej Siewior
2013-08-16 21:21 ` Zubair Lutfullah :
2013-08-17 8:58 ` Zubair Lutfullah :
2013-08-17 8:58 ` Zubair Lutfullah :
[not found] ` <520F9395.3050900@kernel.org>
2013-08-17 18:51 ` Zubair Lutfullah :
2013-08-16 12:53 ` Sebastian Andrzej Siewior
2013-08-16 12:53 ` Sebastian Andrzej Siewior
2013-08-16 21:18 ` Zubair Lutfullah :
2013-08-16 13:25 ` Sebastian Andrzej Siewior
2013-08-16 13:25 ` Sebastian Andrzej Siewior
2013-08-16 21:13 ` Zubair Lutfullah : [this message]
2013-08-16 14:59 ` Sebastian Andrzej Siewior
2013-08-16 14:59 ` Sebastian Andrzej Siewior
2013-08-16 21:10 ` Zubair Lutfullah :
2013-08-19 17:12 ` Sebastian Andrzej Siewior
2013-08-19 17:12 ` Sebastian Andrzej Siewior
2013-08-20 16:26 ` Zubair Lutfullah :
2013-08-20 16:26 ` Zubair Lutfullah :
2013-08-14 18:57 ` [PATCH 0/4] iio: input: ti_am335x_adc: Add continuous sampling support round 5 Jonathan Cameron
2013-08-14 18:05 ` Sebastian Andrzej Siewior
2013-08-16 21:23 ` Zubair Lutfullah :
-- strict thread matches above, loose matches on Subject: below --
2013-08-13 16:48 [PATCH 0/4] iio: input: ti_am335x_adc: Add continuous sampling support round 4 Zubair Lutfullah
2013-08-13 16:48 ` [PATCH 4/4] iio: ti_am335x_adc: Add continuous sampling and trigger support Zubair Lutfullah
2013-08-13 17:05 ` Lee Jones
2013-08-13 17:05 ` Lee Jones
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