AD738x Driver and SPI Engine

Hi

ddickerhoof said:

Clarified

What do you mean by this? Did you already understood all your questions :)?

- Nuno Sá

A new question directly related to this is, do I need to set CONFIG_IIO_BUFFER_CB and/or CONFIG_IIO_BUFFER_HW_CONSUMER in the kernel configuration in order to support the SPI Engine/DMA for streaming?  I'm still tracking this down in the kernel code, so I don't fully understand it yet.  I'm not sure if the ADI AXI-DMAC is the hardware buffering that CONFIG_IIO_BUFFER_HW_CONSUMER references, or this is the in-kernel push mechanism that CONFIG_IIO_BUFFER_CB references.

Hi,

ddickerhoof said:

A new question directly related to this is, do I need to set CONFIG_IIO_BUFFER_CB and/or CONFIG_IIO_BUFFER_HW_CONSUMER in the kernel configuration in order to support the SPI Engine/DMA for streaming?

No, I do not think so. Those drivers are interfaces for in-kernel drivers that need to access IIO devices so they can read/write some channels (typically that is done from userspace).

ddickerhoof said:

I'm not sure if the ADI AXI-DMAC is the hardware buffering

That is the driver for our DMA IP controller that is implemented in HDL... You'll need that enabled. The IIO buffering is done by this one .

ddickerhoof said:

For my application I would like to configure the device to read conversions in 2-wire mode, and I'm trying to understand what changes are necessary to this driver, as well as the axi-spi-engine, offload, and spi execution HDL components.

I cannot say what you'll need to change in the hdl but you'll have to instruct the offload engine about the word (in the spi_transfer) to read (it should be half the bytes as you have two lines).

ddickerhoof said:

I was looking at the ad400x driver for inspiration, but ran into some API differences.

Try to have a look to this one (also supports different number of spi lines) and to the device tree in here...

Hope this helps!

- Nuno Sá

Thanks for the suggestions and links. I'll definitely check out the AD4630.

The link to what does the buffering for the DMA IP gave me a page not found. Can you send me another link or just the name--I can probably find it.

Arghh, probably some issue with EZ as I'm fairly sure I pasted the URL... Anyways:

https://github.com/analogdevicesinc/linux/blob/rpi-5.10.y/drivers/iio/buffer/Kconfig#L22

That needs to be enabled... I guess that you can now figure what driver will be picked by that config :)

Thanks!

Thanks!