Re: iio_simple_dummy_buffer_dma

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

On 02/22/2016 05:51 AM, John Syne wrote:
> BTW, I seem to remember that Lars removed iio_simple_dummy_buffer_dma.c in his V3 patch so this won’t be in the IIO repo, but I don’t know how to test the IIO DMA framework without this file.
>

Hi,

The patch was dropped for now to avoid conflicts with other ongoing work on
the dummy driver. The patch will come back in a slightly overhauled version
soonish.

As for your problem, make sure that you have the part of the patch which
updates things so you can choose in Kconfig whether you want to use the DMA
buffer or the KFIFO buffer. And then select the DMA buffer in your .config.

- Lars


> Regards,
> John
> 
> 
> 
> 
>> On Feb 21, 2016, at 8:41 PM, John Syne <john3909@gmail.com> wrote:
>>
>> Hi,
>>
>> I am interested in using the IIO DMA framework and tried to use your dummy driver. 
>>
>> I attempting to get the iio_dummy working with dma and seem to be having sum difficulty.
>>
>> Here is what I have done so far:
>>
>> I’m working on a BeagleBoneBlack running a 4.1 Linux Kernel. I have back ported the latest IIO code from git://git.kernel.org/pub/scm/linux/kernel/git/jic23
>>
>> As a test I tried ti_am335x_adc.ko and enabled in_voltage0_en and then enabled the buffer. Reading from /dev/iio:device0 provided the waveform of the signal generator I had connected to ADC0 on the board. I was even able to run iiod and then connected IIO Oscilloscope which showed the same waveform. I did get a message WARNING: High-speed mode not enabled, but I guess there is no mmap in the driver and that is probably the issue.
>>
>> In linux config, I have enabled the following:
>> CONFIG_IIO_SIMPLE_DUMMY_EVENTS
>> CONFIG_IIO_SIMPLE_DUMMY_BUFFER
>> CONFIG_IIO_SIMPLE_DUMMY_BUFFER_DMA
>> CONFIG_IIO_BUFFER_CB
>> CONFIG_IIO_BUFFER_DMA
>> CONFIG_IIO_BUFFER_DMAENGINE
>> CONFIG_IIO_KFIFO_BUF
>> CONFIG_IIO_TRIGGERED_BUFFER
>> CONFIG_IIO_TRIGGER
>> CONFIG_IIO_CONSUMERS_PER_TRIGGER 2
>>
>> When I "modprobe iio_dummy”, the following modules are loaded:
>>
>> industrialio
>> industrialio_buffer_dma
>> iio_dummy
>> kfifo_buf
>> iio_dummy_evgen
>>
>> I then modprobe iio_trig_sysfs which gives me /sys/bus/iio/device/iio_sysfs_trigger. To create a trigger I did:
>>
>>> echo 1 > /sys/bus/iio/device/iio_sysfs_trigger/add_trigger
>>> cat name /sys/bus/iio/device/trigger0/name
>>> sysfstrig1
>>> echo sysfstrig1 > /sys/bus/iio/device/iio:device0/trigger/current_trigger
>>
>> Now to enable a measurement:
>>
>>> echo 1 > /sys/bus/iio/device/iio:device0/scan_elements/in_voltage0_en
>>
>> Finally to enable the buffer:
>>
>>> echo 1 /sys/bus/iio/device/iio:device0/buffer/enable
>>
>> When I read "/dev/iio:device0" I get nothing. Connecting IIO Oscilloscope I get the following error message:
>>
>> WARNING: High-speed mode not enabled
>> ERROR: Reading from device failed: -110
>> Client Exited
>>
>> In iio_simple_dummy_buffer_dma.c, I see iio_dummy_dma_source which generates a rect, sine, tri and saw waveforms. Not sure what I need to do to get these waveforms to generate. Is this demo functional?
>>
>>
>> Regards,
>> John
>>
>>
>>
>>
> 
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