From: Jonathan Cameron <jic23@kernel.org>
To: Daniel Baluta <daniel.baluta@intel.com>,
Lars-Peter Clausen <lars@metafoo.de>
Cc: jlbec@evilplan.org, knaack.h@gmx.de,
linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org,
octavian.purdila@intel.com, pebolle@tiscali.nl,
patrick.porlan@intel.com, adriana.reus@intel.com,
constantin.musca@intel.com, marten@intuitiveaerial.com
Subject: Re: [PATCH v5 3/4] iio: trigger: Introduce IIO hrtimer based trigger
Date: Wed, 06 May 2015 18:16:27 +0100 [thread overview]
Message-ID: <554A4C6B.10703@kernel.org> (raw)
In-Reply-To: <554A4065.8050101@intel.com>
On 06/05/15 17:25, Daniel Baluta wrote:
>
>
> On 05/05/2015 04:51 PM, Jonathan Cameron wrote:
>>
>>
>> On 4 May 2015 20:54:08 GMT+01:00, Lars-Peter Clausen <lars@metafoo.de> wrote:
>>> On 05/04/2015 12:50 PM, Daniel Baluta wrote:
>>> [...]
>>>> +IIO_HRTIMER_INFO_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
>>>> + iio_hrtimer_info_show_sampling_frequency,
>>>> + iio_hrtimer_info_store_sampling_frequency);
>>>
>>> I wonder if the sampling frequency should be configurable the regular
>>> IIO
>>> API, just like any other IIO device. But things like min/max sampling
>>> frequency should be configured in configfs.
>> Would have to be in the trigger dir rather than device... Makes sense to put it there.
>> Limits on it here seem like a sensible idea.
>
> But then each trigger will have sampling_frequency right? This is not what we want.
I'm confused now. Why not? Each hrtimer trigger created in configfs should have
it's own sampling frequency should it not?
>
>>>
>>> [...]
>>>> +#endif /* CONFIGFS_FS */
>>>> +
>>> [...]
>>>> +static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char
>>> *name)
>>>> +{
>>> [...]
>>>> +#ifdef CONFIG_CONFIGFS_FS
>>>> + config_group_init_type_name(&trig_info->swt.group, name,
>>>> + &iio_hrtimer_type);
>>>> +#endif
>>>
>>> This should probably have a helper function in the sw trigger core,
>>> that
>>> gets stubbed out when CONFIG_FS is disabled. Otherwise we'll see the
>>> same
>>> #ifdef in every software trigger driver.
>>> [...]
>
> Agree with this. Will fix.
>
>>>> +}
>>>> +
>>>> +static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
>>>> +{
>>>> + struct iio_hrtimer_info *trig_info;
>>>> +
>>>> + trig_info = iio_trigger_get_drvdata(swt->trigger);
>>>> +
>>>> + hrtimer_cancel(&trig_info->timer);
>>>> +
>>>> + iio_trigger_unregister(swt->trigger);
>>>> + iio_trigger_free(swt->trigger);
>>>
>>> There is a bit of a race condition here. hrtimer_cancel() should be
>>> called
>>> between unregister and free, otherwise it might be re-armed before it
>>> is
>>> unregistered.
>
> So this can be re-armed only if the buffer is re-enabled between hrtimer_cancel and iio_trigger_unregister :). I'm trying to understand how the race can happen.
>
>
>>>
>>>> + kfree(trig_info);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
>>>
>>> const
>
> Agree.
>>>
>>>> + .probe = iio_trig_hrtimer_probe,
>>>> + .remove = iio_trig_hrtimer_remove,
>>>> +};
>>> [...]
next prev parent reply other threads:[~2015-05-06 17:16 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-04 10:50 [PATCH v5 0/4] Add initial configfs support for IIO Daniel Baluta
2015-05-04 10:50 ` [PATCH v5 1/4] iio: core: Introduce IIO software triggers Daniel Baluta
2015-05-04 20:11 ` Lars-Peter Clausen
2015-05-06 9:24 ` Daniel Baluta
2015-05-04 10:50 ` [PATCH v5 2/4] iio: core: Introduce IIO configfs support Daniel Baluta
2015-05-04 19:59 ` Lars-Peter Clausen
2015-05-05 13:48 ` Jonathan Cameron
2015-05-06 16:15 ` Daniel Baluta
2015-05-04 10:50 ` [PATCH v5 3/4] iio: trigger: Introduce IIO hrtimer based trigger Daniel Baluta
2015-05-04 19:54 ` Lars-Peter Clausen
2015-05-05 13:51 ` Jonathan Cameron
2015-05-06 16:25 ` Daniel Baluta
2015-05-06 17:16 ` Jonathan Cameron [this message]
2015-05-06 17:37 ` Daniel Baluta
2015-05-07 9:19 ` Jonathan Cameron
2015-05-07 10:26 ` Daniel Baluta
2015-05-07 18:26 ` Lars-Peter Clausen
2015-05-04 10:50 ` [PATCH v5 4/4] iio: Documentation: Add IIO configfs documentation Daniel Baluta
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