Re: ALSA dma_area not utilizing D-cahce

[Paul Mundt <lethal@linux-sh.org>]

On Mon, May 21, 2012 at 10:44:14AM +0900, MASAO TAKAHASHI wrote:
> diff -Nru a/arch/sh/include/asm/page.h b/arch/sh/include/asm/page.h
> --- a/arch/sh/include/asm/page.h	2012-05-21 09:05:58.556556493 +0900
> +++ b/arch/sh/include/asm/page.h	2012-05-21 09:14:44.649922912 +0900
> @@ -136,6 +136,11 @@
>  #define __pa(x)	((unsigned long)(x)-PAGE_OFFSET)
>  #define __va(x)	((void *)((unsigned long)(x)+PAGE_OFFSET))
>  #endif
> +/* add 2012/5/21 */
> +#if defined(CONFIG_29BIT)
> +#define UNCAC_ADDR(addr)	P2SEGADDR(addr)
> +#define CAC_ADDR(addr)		P1SEGADDR(addr)
> +#endif
>  
>  #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
>  #define page_to_phys(page)	(page_to_pfn(page) << PAGE_SHIFT)

Are you using an old kernel? UNCAC_ADDR/CAC_ADDR should already be
defined in page.h, and do the P2/P1 wrapping for the 29-bit phys case.

> +static int	sh7764_pcm_mmap(struct snd_pcm_substream *substream,
> +				struct vm_area_struct *area)
> +{
..
> +#ifdef pgprot_noncached
> +	/*
> + 	 * disable non-chahe attribute cause
> + 	 */ 
> +	area->vm_page_prot = pgprot_noncached(area->vm_page_prot);
> +#endif

You don't want the ifdef here. pgprot_noncached() is now part of the
generic API, so you can always rely on it. It's worse if you don't have
it defined and suddenly end up with a cached attribute for the VMA that
you weren't expecting.

> +	offset = area->vm_pgoff << PAGE_SHIFT;
> +	runtime = substream->runtime;
> +	map_size = runtime->dma_bytes;
> +	mp = (unsigned long)runtime->dma_addr;
> +	map = virt_to_page(mp);
> +	mapend = virt_to_page(mp+map_size - 1);
> +	for (ip = map; ip <= mapend; ip++){
> +		SetPageReserved(ip);
> +	}
> +	area->vm_ops = &sh7764_pcm_vm_ops_data;
> +	area->vm_private_data = substream;
> +	area->vm_flags |= VM_IO;
> +	ret = io_remap_pfn_range(area, area->vm_start, mp>>PAGE_SHIFT, 
> +						area->vm_end - area->vm_start, area->vm_page_prot);
> +	if (ret ){
> +		pr_debug("sh7764-pcm.c:remap_pfn_range returned EAGAIN\n");
> +		return -EAGAIN;
> +	}
> +	atomic_inc(&substream->mmap_count);
> +	return 0;
> +}
> +
Do you really need this? It looks like you could just use
snd_pcm_lib_mmap_iomem() directly.