Re: ALSA on MIPS platform

["Dajie Tan" <jiankemeng@gmail.com>]

Sorry, that aim at 2.6.18.

In the latest kernel:

--- a/include/asm-mips/io.h     2007-08-07 10:18:03.000000000 +0800
+++ b/include/asm-mips/io.h     2007-08-07 10:18:56.000000000 +0800
@@ -116,7 +116,7 @@
  */
 static inline unsigned long virt_to_phys(volatile const void *address)
 {
-       return (unsigned long)address - PAGE_OFFSET + PHYS_OFFSET;
+       return ((unsigned long)address & 0x1fffffff) + PHYS_OFFSET;
 }

I think virt_to_phys or __pa should accept kseg1 address.

Tan

2007/8/7, Dajie Tan <jiankemeng@gmail.com>:
> I think this problem can be solved by revising the __pa macro like this:
>
> --- a/include/asm-mips/page.h      2007-08-07 09:45:00.000000000 +0800
> +++ b/include/asm-mips/page.h     2007-08-07 09:46:59.000000000 +0800
> @@ -150,7 +150,7 @@
>  })
>  #else
>  #define __pa(x)
>          \
> -    ((unsigned long)(x) - PAGE_OFFSET + PHYS_OFFSET)
> +    (((unsigned long)(x) & 0x1fffffff) + PHYS_OFFSET)
>  #endif
>
> So, the virt_to_page can accept all cached or uncached address.
>
>
> Tan
>
> 2007/8/3, Songmao Tian <tiansm@lemote.com>:
> > Atsushi Nemoto wrote:
> > > On Wed, 01 Aug 2007 15:56:48 +0800, Songmao Tian <tiansm@lemote.com> 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++;
> >      }
> >
> >
>


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