On Tue, 5 Nov 2019 09:01:35 +0100
Takashi Iwai <tiwai@xxxxxxx> wrote:
> Currently we pass the artificial device pointer to the allocation
> helper in the case of SNDRV_DMA_TYPE_CONTINUOUS for passing the GFP
> flags. But all common cases are the allocations with GFP_KERNEL, and
> it's messy to put this in each place.
>
> In this patch, the memalloc core helper is changed to accept the NULL
> device pointer and it treats as the default mode, GFP_KERNEL, so that
> all callers can omit the complex argument but just leave NULL.
>
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
> ---
> Documentation/sound/kernel-api/writing-an-alsa-driver.rst | 14 ++++++++------
> sound/core/memalloc.c | 9 ++++++++-
> 2 files changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
> index 132f5eb9b530..5385618fd881 100644
> --- a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
> +++ b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
> @@ -3523,12 +3523,14 @@ The second argument (type) and the third argument (device pointer) are
> dependent on the bus. For normal devices, pass the device pointer
> (typically identical as ``card->dev``) to the third argument with
> ``SNDRV_DMA_TYPE_DEV`` type. For the continuous buffer unrelated to the
> -bus can be pre-allocated with ``SNDRV_DMA_TYPE_CONTINUOUS`` type and the
> -``snd_dma_continuous_data(GFP_KERNEL)`` device pointer, where
> -``GFP_KERNEL`` is the kernel allocation flag to use. For the
> -scatter-gather buffers, use ``SNDRV_DMA_TYPE_DEV_SG`` with the device
> -pointer (see the `Non-Contiguous Buffers`_
> -section).
> +bus can be pre-allocated with ``SNDRV_DMA_TYPE_CONTINUOUS`` type.
> +You can pass NULL to the device pointer in that case, which is the
> +default mode implying to allocate with ``GFP_KRENEL`` flag.
> +If you need a different GFP flag, you can pass it by encoding the flag
> +into the device pointer via a special macro
> +:c:func:`snd_dma_continuous_data()`.
> +For the scatter-gather buffers, use ``SNDRV_DMA_TYPE_DEV_SG`` with the
> +device pointer (see the `Non-Contiguous Buffers`_ section).
>
> Once the buffer is pre-allocated, you can use the allocator in the
> ``hw_params`` callback:
> diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
> index 6850d13aa98c..e56f84fbd659 100644
> --- a/sound/core/memalloc.c
> +++ b/sound/core/memalloc.c
> @@ -99,6 +99,13 @@ static void snd_free_dev_iram(struct snd_dma_buffer *dmab)
> *
> */
>
> +static inline gfp_t snd_mem_get_gfp_flags(const struct device *dev)
> +{
> + if (!dev)
> + return GFP_KRENEL;
There is a typo, you remove it in next patch, but it may cause problem
with bisects.
> + else
> + return (__force gfp_t)(unsigned long)dev;
> +}
>
> /**
> * snd_dma_alloc_pages - allocate the buffer area according to the given type
> @@ -129,7 +136,7 @@ int snd_dma_alloc_pages(int type, struct device *device, size_t size,
> switch (type) {
> case SNDRV_DMA_TYPE_CONTINUOUS:
> dmab->area = alloc_pages_exact(size,
> - (__force gfp_t)(unsigned long)device);
> + snd_mem_get_gfp_flags(device));
> dmab->addr = 0;
> break;
> #ifdef CONFIG_HAS_DMA
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