Re: [PATCH] dmaengine: axi-dmac: Sanity check memory mapped interface support

[Vinod Koul <vkoul@kernel.org>]

On 16-05-19, 11:31, Alexandru Ardelean wrote:
> From: Lars-Peter Clausen <lars@metafoo.de>
> 
> The AXI-DMAC supports different types of interface for the data source and
> destination ports. Typically one of those ports is a memory-mapped
> interface while the other is some kind of streaming interface.
> 
> The information about which kind of interface is used for each port is
> encoded in the devicetree.
> 
> It is also possible in the driver to detect whether a port supports
> memory-mapped transfers or not. For streaming interfaces the address
> register is read-only and will always return 0. So in order to check if a
> port supports memory-mapped transfers write a non-zero value to the
> corresponding address register and check that the value read-back is still
> non zero.
> 
> This allows to detect mismatches between the devicetree description and the
> actual hardware configuration.
> 
> Unfortunately it is not possible to autodetect the interface types since
> there is no method to distinguish between the different streaming ports. So
> the best thing that can be done is to error out when a memory mapped port
> is described in the devicetree but none is detected in the hardware.

Applied, thanks

-- 
~Vinod