Re: [PATCH] qlogicpti: Fix compiler warnings

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Wed, 2016-11-23 at 13:29 -0800, Tushar Dave wrote:
> qlogicpti uses '__u32' for dma handle while invoking kernel DMA APIs,
> instead of using dma_addr_t. This hasn't caused any 'incompatible
> pointer type' warning on SPARC because until now dma_addr_t is of
> type u32. However, recent changes in SPARC ATU (iommu) enabled 64bit
> DMA and therefore dma_addr_t became of type u64. This makes
> 'incompatible pointer type' warnings inevitable.
> 
> e.g.
> drivers/scsi/qlogicpti.c: In function ‘qpti_map_queues’:
> drivers/scsi/qlogicpti.c:813: warning: passing argument 3 of
> ‘dma_alloc_coherent’ from incompatible pointer type
> ./include/linux/dma-mapping.h:445: note: expected ‘dma_addr_t *’ but
> argument is of type ‘__u32 *’
> drivers/scsi/qlogicpti.c:822: warning: passing argument 3 of
> ‘dma_alloc_coherent’ from incompatible pointer type
> ./include/linux/dma-mapping.h:445: note: expected ‘dma_addr_t *’ but
> argument is of type ‘__u32 *’
> 
> This patch resolves above compiler warnings.

There appears to be no point to the first three hunks of this diff:

(ushort)(x << 16) 
(ushort)(x & 0xffff)

return the same thing whether the type of x is u32 or u64, so there was
no need to alter the original code.

What's the guarantee, since the device descriptors only cope with 32
bits of physical address, that this driver never gets any dma address
beyond its addressable range?  Is it that the sbus can never be
attached to this ATU type IOMMU?  If so, saying that in the log would
be useful.

James