Atsushi Nemoto wrote:
On Wed, 01 Aug 2007 15:56:48 +0800, Songmao Tian <tiansm@xxxxxxxxxx> wrote:
The problem is clear:
1. 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++;
}
