Messages in this thread Patch in this message | | | Date | Wed, 20 Feb 2019 16:20:53 +0100 | From | Thomas Bogendoerfer <> | Subject | Re: [PATCH 6/7] MIPS: SGI-IP27: use generic PCI driver |
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On Wed, 20 Feb 2019 07:10:56 -0800 Christoph Hellwig <hch@infradead.org> wrote:
> On Mon, Feb 18, 2019 at 11:58:07AM +0100, Thomas Bogendoerfer wrote: > > This of course will break SH7786. To fix both cases how about making dma_pfn_offset > > > > a signed long ? > > Yes, making it signed sounds like a good idea.
but at least my implementation looks a little bit ugly:
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h index b7338702592a..b72b1cba8911 100644 --- a/include/linux/dma-direct.h +++ b/include/linux/dma-direct.h @@ -12,14 +12,20 @@ static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr) { dma_addr_t dev_addr = (dma_addr_t)paddr; - return dev_addr - ((dma_addr_t)dev->dma_pfn_offset << PAGE_SHIFT); + if (dev->dma_pfn_offset > 0) + return dev_addr + ((dma_addr_t)dev->dma_pfn_offset << PAGE_SHIFT); + + return dev_addr - ((dma_addr_t)-dev->dma_pfn_offset << PAGE_SHIFT); } static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dev_addr) { phys_addr_t paddr = (phys_addr_t)dev_addr; - return paddr + ((phys_addr_t)dev->dma_pfn_offset << PAGE_SHIFT); + if (dev->dma_pfn_offset > 0) + return paddr - ((phys_addr_t)dev->dma_pfn_offset << PAGE_SHIFT); + + return paddr + ((phys_addr_t)-dev->dma_pfn_offset << PAGE_SHIFT); } static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
For the v2 version of the IP27 rework I've used the mach-XXX include structure of the MIPS tree to implement __phy_to_dma/__dma_to_phys for IP27. I'd prefer it that way.
Thomas.
-- SUSE Linux GmbH GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg)
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