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-rw-r--r--Documentation/sound/kernel-api/writing-an-alsa-driver.rst14
-rw-r--r--sound/core/memalloc.c11
2 files changed, 16 insertions, 9 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..1b1c7620cbda 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_KERNEL;
+ else
+ return (__force gfp_t)(unsigned long)dev;
+}
/**
* snd_dma_alloc_pages - allocate the buffer area according to the given type
@@ -120,8 +127,6 @@ int snd_dma_alloc_pages(int type, struct device *device, size_t size,
return -ENXIO;
if (WARN_ON(!dmab))
return -ENXIO;
- if (WARN_ON(!device))
- return -EINVAL;
dmab->dev.type = type;
dmab->dev.dev = device;
@@ -129,7 +134,7 @@ 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