Atsushi Nemoto wrote:
On Wed, 01 Aug 2007 15:56:48 +0800, Songmao Tian tiansm@lemote.com wrote:
The problem is clear:
- dma_alloc_noncoherent() return a non-cached address, and
virt_to_page() need a cached logical addr (Have I named it right?) 2. mmaped dam buffer should be non-cached.
We have a ugly patch, but we want to solve the problem cleanly, so can anyone show me the way?
virt_to_page() is used in many place in mm so making it robust might affect performance. IMHO virt_to_page() seems too low-level as DMA API.
If something like dma_virt_to_page(dev, cpu_addr) which can take a cpu address returned by dma_xxx APIs was defined, MIPS can implement it appropriately.
And then pgprot_noncached issues still exist...
Atsushi Nemoto
I agree, and I am investigating to implement a dma_map_coherent, but It seems dma_map_coherent doesn't solve all the problem and will change a lot of code:(
dma_virt_to_page can be something like this.
diff --git a/include/asm-mips/page.h b/include/asm-mips/page.h index b92dd8c..d2ead8a 100644 --- a/include/asm-mips/page.h +++ b/include/asm-mips/page.h @@ -181,6 +181,8 @@ typedef struct { unsigned long pgprot; } pgprot_t; #define virt_to_page(kaddr) pfn_to_page(PFN_DOWN(virt_to_phys(kaddr))) #define virt_addr_valid(kaddr) pfn_valid(PFN_DOWN(virt_to_phys(kaddr)))
+#define dma_virt_to_page(dma_addr) pfn_to_page(PFN_DOWN(virt_to_phys(CAC_ADDR(kaddr)))) + #define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_EXEC | \ VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
diff --git a/include/linux/mm.h b/include/linux/mm.h index 655094d..5e694dd 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -39,6 +39,10 @@ extern int sysctl_legacy_va_layout; #include <asm/pgtable.h> #include <asm/processor.h>
+#ifndef dma_virt_to_page +#define dma_virt_to_page virt_to_page +#endif + #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))
/* diff --git a/sound/core/sgbuf.c b/sound/core/sgbuf.c index cefd228..8b29bfd 100644 --- a/sound/core/sgbuf.c +++ b/sound/core/sgbuf.c @@ -91,7 +91,7 @@ void *snd_malloc_sgbuf_pages(struct device *device, } sgbuf->table[i].buf = tmpb.area; sgbuf->table[i].addr = tmpb.addr; - sgbuf->page_table[i] = virt_to_page(tmpb.area); + sgbuf->page_table[i] = dma_virt_to_page(tmpb.area); sgbuf->pages++; }