Re: Trouble with allocating memory on platform driver

On Fri, 17 Apr 2020 10:47:33 +0200, "s.achterop@rug.nl" said:

I found a working solution. I actually don't know what I am doing but it works. Before the call to dma_zalloc_coherent I added:

pdev->dev.coherent_dma_mask = 0xffffffff;

DMA_BIT_MASK(32) rather than a hex constant would be a better choice.

Now it works.

Note that "works" and "is correct" are two different things. That should be a mask that tells how many bits of the value are actually used by the hardware. On most 32-bit systems, 32 will be correct, but there's other values in use (on S/390, it's either 31 or 64 bits, the PowerPC can have 44, and the old PNP stuff on x86 weirds out at the 24-bit line).