Re: [PATCH] firmware: qcom_scm: fix error for incompatible pointer

[Christoph Hellwig]

On Mon, Jul 22, 2019 at 10:38:55AM +0200, Marc Gonzalez wrote:
> > In file included from drivers/firmware/qcom_scm.c:12:0:
> > ./include/linux/dma-mapping.h:636:21: note: expected âdma_addr_t * {aka long long unsigned int *}â but argument is of type âphys_addr_t * {aka unsigned int *}â
> >  static inline void *dma_alloc_coherent(struct device *dev, size_t size,
> >                      ^~~~~~~~~~~~~~~~~~
> > ```
> > 
> > We just can cast phys_addr_t to dma_addr_t here.
> 
> IME, casting is rarely a proper solution.

*nod*

ptr_phys probably should be a dma_addr_t.  Unless this driver is so
magic that it really wants a physical and not a dma address, in which
case it needs to use alloc_pages instead of dma_alloc_coherent
and then call page_to_phys on the returned page, and a very big comment
explaining why it is so special.