Re: IIO Drivers

[Lars-Peter Clausen <lars@metafoo.de>]

On 02/27/2013 09:06 PM, Chris Micali wrote:
> Thanks lars - i'm actually on 3.8, you don't happen to have a DT example do you?    

uhm, should be just as simple:

hrtimer-trigger@0 {
	compatible = "iio-trigger-hrtimer";
};

You need to add the proper of match table to the driver though.

- Lars

> 
> 
> On Wednesday, February 27, 2013 at 3:02 PM, Lars-Peter Clausen wrote:
> 
>> On 02/27/2013 08:50 PM, Chris Micali wrote:
>>> Last question :) I'd like to sample from this device as quickly as possible - so I'm assuming I need to trigger quickly? Should I use iio-trig-periodic-rtc? Any hints/instructions on how to use that? Should the driver supply it's own trigger that uses an hrtimer instead?
>>>  
>>> Thanks!
>>> Chris
>>  
>>  
>>  
>> Hi,
>>  
>> There is a generic hrtimer based trigger:
>> https://github.com/lclausen-adi/linux-2.6/commit/a3b5c3f7aafbcac562d6f00a6589b110bd9fb71c
>>  
>> Unfortunately it's not upstream ready yet.
>>  
>> I can be registered via a platform_device
>>  
>> static struct platform_device iio_trigger_hrtimer = {
>> .name = "iio-trigger-hrtimer",
>> .id = 0,
>> };
>>  
>> - Lars
>>  
>>>  
>>>  
>>> On Wednesday, February 27, 2013 at 2:32 PM, Chris Micali wrote:  
>>>> Guys,  
>>>>  
>>>> Thanks a lot for the help! I finally tracked down issues, it was a combination of a few things:
>>>>  
>>>> 1. The .channel had to be 0, not 1 in the driver (scan_index didn't matter)
>>>> 2. 1 or more scan_elements have to be enabled as you mentioned
>>>> 2. When echoing into the sysfs files it has to have a space after the number (cat 1 > in_voltage0_en and not cat 1>in_vo…) (duh!)
>>>> 3. The generic_buffer.c program had a few bugs in it causing crashes. I updated the iio_utils.h to a newer version I found here: https://github.com/analogdevicesinc/iio-oscilloscope and then made a few modifications (the newer iio_utils did not parse a few things right in the channel details like bigendian/littleendian)
>>>>  
>>>> So generic_buffer is now correctly sampling (although it crashes after a couple, it's probably another iio_utils issue)
>>>>  
>>>> Thanks!!
>>>>  
>>>> -chris
>>>>  
>>>>  
>>>> On Wednesday, February 27, 2013 at 1:51 PM, Lars-Peter Clausen wrote:
>>>>  
>>>>> On 02/27/2013 07:28 PM, Jonathan Cameron wrote:
>>>>>> On 02/27/2013 05:36 PM, Chris Micali wrote:
>>>>>>> lars,  
>>>>>>>  
>>>>>>> I was under the impression that flag gets added automatically by iio_triggered_buffer_setup (industrialiio-triggers.c:77) - I actually am now able to enable the scan_element after changing my channel .channel and .scan_index to 0 (trying to match exactly the other drivers.)
>>>>>  
>>>>>  
>>>>>  
>>>>> Yea, you are right I missed the iio_triggered_buffer_setup part.
>>>>>  
>>>>>> Strange, scan_index should have defaulted to zero and the .channel value shouldn't have mattered
>>>>>> for buffered reads (just effects naming). Might have caused issues with userspace expecting a channel 0
>>>>>> though...
>>>>>  
>>>>>  
>>>>>  
>>>>>  
>>>>>  
>>>>>  
>>>>>  
>>>>> I guess the scan_index had nothing to do with this, but I suggested to set
>>>>> scan_elements/in_voltage0_en to 1, so this clearly wouldn't have worked with
>>>>> .channel being 1.
>>>>>  
>>>>>>  
>>>>>>> When i run general_buffer (from the docs dir) with that scan element enabled it can no longer read the trigger (Could not open /trigger/current_trigger Failed to write current_trigger file) - this succeeds if that scan_element is not enabled.  
>>>>>  
>>>>>  
>>>>>  
>>>>> You can't change the trigger if the buffer is currently enabled. Make sure that
>>>>> he buffer is disabled (check the buffer/enable attribute).
>>>>>  
>>>>> - Lars
>>>>> u
>>>>  
>>>  
>>>  
>>>  
>>>  
>>>  
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>>  
> 
> 
>