Re: Ecovec (SH7724) board doesn't work on latest linus tree

From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
To: linux-sh@vger.kernel.org
Subject: Re: Ecovec (SH7724) board doesn't work on latest linus tree
Date: Thu, 01 Sep 2011 01:45:53 +0000	[thread overview]
Message-ID: <874o0xc9wy.wl%kuninori.morimoto.gx@renesas.com> (raw)
In-Reply-To: <w3pvcwf5xuu.wl%kuninori.morimoto.gx@renesas.com>

Hi Paul

> I guess your patch tried to share code for sh32/sh64.
> and CAC_ADDR() should be equal P1SEGADDR(), correct ?
> 
> I'm not filmier with memory control, but
> on Ecovec case, 1st (and crash case) dma_cache_sync() caller is
> ${LINUX}/arch/sh/mm/consistent.c :: dma_generic_alloc_coherent()
> 
> it tried
> 
> 	ret = (void *)__get_free_pages(gfp, order);
>         (snip)
>         dma_cache_sync(dev, ret, size, DMA_BIDIRECTIONAL);
> 
> This "ret" is "8e000000" for now.
> 
> but CAC_ADDR(xx)/P1SEGADDR(xx) is defined as below
> 
> CAC_ADDR(addr)  ((addr) - uncached_start + PAGE_OFFSET)
> P1SEGADDR(a)    ((__typeof__(a))(((unsigned long)(a) & 0x1fffffff) | P1SEG))
> 
> I guess this "ret" should be uncached area if dma_cache_sync(xx) use CAC_ADDR(xx).
> 
> If I apply below patch, Ecovec start works without crash, but I'm not sure.
> Is this correct patch ?
> 
> --------------------
> diff --git a/arch/sh/mm/consistent.c b/arch/sh/mm/consistent.c
> index f251b5f..198234a 100644
> --- a/arch/sh/mm/consistent.c
> +++ b/arch/sh/mm/consistent.c
> @@ -48,7 +48,7 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t si
>          * Pages from the page allocator may have data present in
>          * cache. So flush the cache before using uncached memory.
>          */
> -       dma_cache_sync(dev, ret, size, DMA_BIDIRECTIONAL);
> +       dma_cache_sync(dev, UNCAC_ADDR(ret), size, DMA_BIDIRECTIONAL);
>  
>         ret_nocache = (void __force *)ioremap_nocache(virt_to_phys(ret), size);
>         if (!ret_nocache) {
> -------------------------
> 
> But I'm afraid below comment of dma_generic_alloc_coherent()
> 
> 	/*
> 	 * Pages from the page allocator may have data present in
> 	 * cache. So flush the cache before using uncached memory.
> 	 */
> 	dma_cache_sync(dev, ret, size, DMA_BIDIRECTIONAL);

dma_cache_sync(xx) should not expect vaddr is in uncached area ?

Best regards
---
Kuninori Morimoto