Re: [PATCH V2 1/2] ALSA: Support writecombine DMA buffer memory page alloc/free
From: Takashi Iwai
Date: Mon Jul 02 2012 - 05:09:39 EST
At Mon, 2 Jul 2012 14:24:32 +0530,
Laxman Dewangan wrote:
>
> Some of architecture like ARM support the writecombine DMA
> buffer which is used for pcm substream DMA buffer.
>
> Supporting writecombine DMA buffer allocation/free/mmap
> through the sound library memory management.
>
> Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
> ---
> Changes from V1:
> Integrate the changes from Takashi's sample code for supporting
> writecombine.
Could you give a short comment in each file that ifdef CONFIG_ARM is a
workaround?
thanks,
Takashi
>
> include/sound/memalloc.h | 1 +
> sound/core/memalloc.c | 74 +++++++++++++++++++++++++++++++++++++++++-----
> sound/core/pcm_native.c | 10 ++++++
> 3 files changed, 77 insertions(+), 8 deletions(-)
>
> diff --git a/include/sound/memalloc.h b/include/sound/memalloc.h
> index c425062..0328e37 100644
> --- a/include/sound/memalloc.h
> +++ b/include/sound/memalloc.h
> @@ -52,6 +52,7 @@ struct snd_dma_device {
> #else
> #define SNDRV_DMA_TYPE_DEV_SG SNDRV_DMA_TYPE_DEV /* no SG-buf support */
> #endif
> +#define SNDRV_DMA_TYPE_DEV_WC 4 /* writecombine page */
>
> /*
> * info for buffer allocation
> diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
> index 6915692..7468251 100644
> --- a/sound/core/memalloc.c
> +++ b/sound/core/memalloc.c
> @@ -124,8 +124,10 @@ void snd_free_pages(void *ptr, size_t size)
> */
>
> #ifdef CONFIG_HAS_DMA
> -/* allocate the coherent DMA pages */
> -static void *snd_malloc_dev_pages(struct device *dev, size_t size, dma_addr_t *dma)
> +static void *_snd_malloc_dev_pages(struct device *dev, size_t size,
> + dma_addr_t *dma,
> + void *(*alloc_func)(struct device *dev, size_t size,
> + dma_addr_t *dma, gfp_t gfp_flags))
> {
> int pg;
> void *res;
> @@ -138,16 +140,18 @@ static void *snd_malloc_dev_pages(struct device *dev, size_t size, dma_addr_t *d
> | __GFP_COMP /* compound page lets parts be mapped */
> | __GFP_NORETRY /* don't trigger OOM-killer */
> | __GFP_NOWARN; /* no stack trace print - this call is non-critical */
> - res = dma_alloc_coherent(dev, PAGE_SIZE << pg, dma, gfp_flags);
> + res = alloc_func(dev, PAGE_SIZE << pg, dma, gfp_flags);
> if (res != NULL)
> inc_snd_pages(pg);
>
> return res;
> }
>
> -/* free the coherent DMA pages */
> -static void snd_free_dev_pages(struct device *dev, size_t size, void *ptr,
> - dma_addr_t dma)
> +static void _snd_free_dev_pages(struct device *dev, size_t size, void *ptr,
> + dma_addr_t dma,
> + void (*free_func)(struct device *dev,
> + size_t size, void *vaddr,
> + dma_addr_t dma_handle))
> {
> int pg;
>
> @@ -155,8 +159,51 @@ static void snd_free_dev_pages(struct device *dev, size_t size, void *ptr,
> return;
> pg = get_order(size);
> dec_snd_pages(pg);
> - dma_free_coherent(dev, PAGE_SIZE << pg, ptr, dma);
> + free_func(dev, PAGE_SIZE << pg, ptr, dma);
> +}
> +
> +static void *_dma_alloc_coherent(struct device *dev, size_t size,
> + dma_addr_t *dma_handle, gfp_t flag)
> +{
> + return dma_alloc_coherent(dev, size, dma_handle, flag);
> +}
> +
> +static void _dma_free_coherent(struct device *dev, size_t size,
> + void *vaddr, dma_addr_t dma_handle)
> +{
> + dma_free_coherent(dev, size, vaddr, dma_handle);
> +}
> +
> +
> +/* allocate the coherent DMA pages */
> +static void *snd_malloc_dev_pages(struct device *dev, size_t size,
> + dma_addr_t *dma)
> +{
> + return _snd_malloc_dev_pages(dev, size, dma, _dma_alloc_coherent);
> +}
> +
> +/* free the coherent DMA pages */
> +static void snd_free_dev_pages(struct device *dev, size_t size, void *ptr,
> + dma_addr_t dma)
> +{
> + _snd_free_dev_pages(dev, size, ptr, dma, _dma_free_coherent);
> }
> +
> +#ifdef CONFIG_ARM
> +/* allocate the writecombine DMA pages */
> +static void *snd_malloc_dev_wc_pages(struct device *dev, size_t size,
> + dma_addr_t *dma)
> +{
> + return _snd_malloc_dev_pages(dev, size, dma, dma_alloc_writecombine);
> +}
> +
> +/* free the writecombine DMA pages */
> +static void snd_free_dev_wc_pages(struct device *dev, size_t size, void *ptr,
> + dma_addr_t dma)
> +{
> + _snd_free_dev_pages(dev, size, ptr, dma, dma_free_writecombine);
> +}
> +#endif
> #endif /* CONFIG_HAS_DMA */
>
> /*
> @@ -200,6 +247,11 @@ int snd_dma_alloc_pages(int type, struct device *device, size_t size,
> case SNDRV_DMA_TYPE_DEV:
> dmab->area = snd_malloc_dev_pages(device, size, &dmab->addr);
> break;
> +#ifdef CONFIG_ARM
> + case SNDRV_DMA_TYPE_DEV_WC:
> + dmab->area = snd_malloc_dev_wc_pages(device, size, &dmab->addr);
> + break;
> +#endif
> #endif
> #ifdef CONFIG_SND_DMA_SGBUF
> case SNDRV_DMA_TYPE_DEV_SG:
> @@ -272,6 +324,12 @@ void snd_dma_free_pages(struct snd_dma_buffer *dmab)
> case SNDRV_DMA_TYPE_DEV:
> snd_free_dev_pages(dmab->dev.dev, dmab->bytes, dmab->area, dmab->addr);
> break;
> +#ifdef CONFIG_ARM
> + case SNDRV_DMA_TYPE_DEV_WC:
> + snd_free_dev_wc_pages(dmab->dev.dev, dmab->bytes, dmab->area,
> + dmab->addr);
> + break;
> +#endif
> #endif
> #ifdef CONFIG_SND_DMA_SGBUF
> case SNDRV_DMA_TYPE_DEV_SG:
> @@ -378,7 +436,7 @@ static int snd_mem_proc_read(struct seq_file *seq, void *offset)
> long pages = snd_allocated_pages >> (PAGE_SHIFT-12);
> struct snd_mem_list *mem;
> int devno;
> - static char *types[] = { "UNKNOWN", "CONT", "DEV", "DEV-SG" };
> + static char *types[] = { "UNKNOWN", "CONT", "DEV", "DEV-SG" , "WC"};
>
> mutex_lock(&list_mutex);
> seq_printf(seq, "pages : %li bytes (%li pages per %likB)\n",
> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> index 53b5ada..28d949c 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -3170,6 +3170,16 @@ int snd_pcm_lib_default_mmap(struct snd_pcm_substream *substream,
> struct vm_area_struct *area)
> {
> area->vm_flags |= VM_RESERVED;
> +
> +#ifdef CONFIG_ARM
> + if (substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV_WC)
> + return dma_mmap_writecombine(substream->dma_buffer.dev.dev,
> + area,
> + substream->runtime->dma_area,
> + substream->runtime->dma_addr,
> + area->vm_end - area->vm_start);
> +#endif
> +
> #ifdef ARCH_HAS_DMA_MMAP_COHERENT
> if (!substream->ops->page &&
> substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV)
> --
> 1.7.1.1
>
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