Subject: Re: [PATCH] powerpc: Add pgprot_writecombine

From: Nishanth Aravamudan <[email-masked]>
Date: Mon, 14 Mar 2011 11:33:00 -0700

On 01.03.2011 [17:00:47 +1100], Anton Blanchard wrote:
> 
> A number of drivers are using pgprot_writecombine() to enable write
> combining on userspace mappings. Implement it on powerpc.

Given this patch, should drivers/infiniband/hw/cxgb4/t4.h

be updated?:

static inline pgprot_t t4_pgprot_wc(pgprot_t prot)
{
#if defined(__i386__) || defined(__x86_64__)
        return pgprot_writecombine(prot);
#elif defined(CONFIG_PPC64)
        return __pgprot((pgprot_val(prot) | _PAGE_NO_CACHE) &
                        ~(pgprot_t)_PAGE_GUARDED);
#else
        return pgprot_noncached(prot);
#endif
}

Thanks,
Nish

> Signed-off-by: Anton Blanchard <[email-masked]>
> ---
> 
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index 89f1587..88b0bd9 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -170,6 +170,7 @@ extern int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long addre
>  #define pgprot_cached_wthru(prot) (__pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) | \
>  				            _PAGE_COHERENT | _PAGE_WRITETHRU))
> 
> +#define pgprot_writecombine pgprot_noncached_wc
> 
>  struct file;
>  extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
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-- 
Nishanth Aravamudan <[email-masked]>
IBM Linux Technology Center