The Linux Manuals (man pages) document is an important part of Linux documents. Linux Manuals are organized as several sections. Each section has a group of commands for a specific area in Linux usage, administration or development.
snd_pcm_mmap_data_close – decrease the mmap counter Synopsis void snd_pcm_mmap_data_close(struct vm_area_struct *area); Arguments area VMA Description PCM mmap callback should handle this counter properly Copyright
snd_pcm_limit_isa_dma_size – Get the max size fitting with ISA DMA transfer Synopsis void snd_pcm_limit_isa_dma_size(int dma, size_t *max); Arguments dma DMA number max pointer to store the max size Copyright
snd_pcm_limit_hw_rates – determine rate_min/rate_max fields Synopsis int snd_pcm_limit_hw_rates(struct snd_pcm_runtime *runtime); Arguments runtime the runtime instance Description Determines the rate_min and rate_max fields from the rates bits of the given runtime->hw. Return Zero if successful. Copyright
snd_pcm_lib_preallocate_pages_for_all – pre-allocation for continuous memory type (all substreams) Synopsis int snd_pcm_lib_preallocate_pages_for_all(struct snd_pcm *pcm, int type, void *data, size_t size, size_t max); Arguments pcm the pcm instance type DMA type (SNDRV_DMA_TYPE_*) data DMA type dependent data size the requested pre-allocation size in bytes max the max. allowed pre-allocation size Description Do pre-allocation to all substreams…
snd_pcm_lib_preallocate_pages – pre-allocation for the given DMA type Synopsis int snd_pcm_lib_preallocate_pages(struct snd_pcm_substream *substream, int type, struct device *data, size_t size, size_t max); Arguments substream the pcm substream instance type DMA type (SNDRV_DMA_TYPE_*) data DMA type dependent data size the requested pre-allocation size in bytes max the max. allowed pre-allocation size Description Do pre-allocation for the…
snd_pcm_lib_preallocate_free_for_all – release all pre-allocated buffers on the pcm Synopsis int snd_pcm_lib_preallocate_free_for_all(struct snd_pcm *pcm); Arguments pcm the pcm instance Description Releases all the pre-allocated buffers on the given pcm. Return Zero if successful, or a negative error code on failure. Copyright
snd_pcm_lib_period_bytes – Get the period size of the current PCM in bytes Synopsis size_t snd_pcm_lib_period_bytes(struct snd_pcm_substream *substream); Arguments substream PCM substream Copyright
snd_pcm_lib_mmap_iomem – Default PCM data mmap function for I/O mem Synopsis int snd_pcm_lib_mmap_iomem(struct snd_pcm_substream *substream, struct vm_area_struct *area); Arguments substream PCM substream area VMA Description When your hardware uses the iomapped pages as the hardware buffer and wants to mmap it, pass this function as mmap pcm_ops. Note that this is supposed to work only…
snd_pcm_lib_malloc_pages – allocate the DMA buffer Synopsis int snd_pcm_lib_malloc_pages(struct snd_pcm_substream *substream, size_t size); Arguments substream the substream to allocate the DMA buffer to size the requested buffer size in bytes Description Allocates the DMA buffer on the BUS type given earlier to snd_pcm_lib_preallocate_xxx_pages. Return 1 if the buffer is changed, 0 if not changed, or…
snd_pcm_lib_ioctl – a generic PCM ioctl callback Synopsis int snd_pcm_lib_ioctl(struct snd_pcm_substream *substream, unsigned int cmd, void *arg); Arguments substream the pcm substream instance cmd ioctl command arg ioctl argument Description Processes the generic ioctl commands for PCM. Can be passed as the ioctl callback for PCM ops. Return Zero if successful, or a negative error…
snd_pcm_lib_get_vmalloc_page – map vmalloc buffer offset to page struct Synopsis struct page *snd_pcm_lib_get_vmalloc_page(struct snd_pcm_substream *substream, unsigned long offset); Arguments substream the substream with a buffer allocated by snd_pcm_lib_alloc_vmalloc_buffer offset offset in the buffer Description This function is to be used as the page callback in the PCM ops. Return The page struct, or NULL on…
snd_pcm_lib_free_vmalloc_buffer – free vmalloc buffer Synopsis int snd_pcm_lib_free_vmalloc_buffer(struct snd_pcm_substream *substream); Arguments substream the substream with a buffer allocated by snd_pcm_lib_alloc_vmalloc_buffer Return Zero if successful, or a negative error code on failure. Copyright
snd_pcm_lib_free_pages – release the allocated DMA buffer. Synopsis int snd_pcm_lib_free_pages(struct snd_pcm_substream *substream); Arguments substream the substream to release the DMA buffer Description Releases the DMA buffer allocated via snd_pcm_lib_malloc_pages. Return Zero if successful, or a negative error code on failure. Copyright
snd_pcm_lib_default_mmap – Default PCM data mmap function Synopsis int snd_pcm_lib_default_mmap(struct snd_pcm_substream *substream, struct vm_area_struct *area); Arguments substream PCM substream area VMA Description This is the default mmap handler for PCM data. When mmap pcm_ops is NULL, this function is invoked implicitly. Copyright
snd_pcm_lib_buffer_bytes – Get the buffer size of the current PCM in bytes Synopsis size_t snd_pcm_lib_buffer_bytes(struct snd_pcm_substream *substream); Arguments substream PCM substream Copyright
snd_pcm_lib_alloc_vmalloc_buffer – allocate virtual DMA buffer Synopsis int snd_pcm_lib_alloc_vmalloc_buffer(struct snd_pcm_substream *substream, size_t size); Arguments substream the substream to allocate the buffer to size the requested buffer size, in bytes Description Allocates the PCM substream buffer using vmalloc, i.e., the memory is contiguous in kernel virtual space, but not in physical memory. Use this if the…
snd_pcm_lib_alloc_vmalloc_32_buffer – allocate 32-bit-addressable buffer Synopsis int snd_pcm_lib_alloc_vmalloc_32_buffer(struct snd_pcm_substream *substream, size_t size); Arguments substream the substream to allocate the buffer to size the requested buffer size, in bytes Description This function works like snd_pcm_lib_alloc_vmalloc_buffer, but uses vmalloc_32, i.e., the pages are allocated from 32-bit-addressable memory. Return 1 if the buffer was changed, 0 if not…
snd_pcm_hw_rule_noresample – add a rule to allow disabling hw resampling Synopsis int snd_pcm_hw_rule_noresample(struct snd_pcm_runtime *runtime, unsigned int base_rate); Arguments runtime PCM runtime instance base_rate the rate at which the hardware does not resample Return Zero if successful, or a negative error code on failure. Copyright
snd_pcm_hw_rule_add – add the hw-constraint rule Synopsis int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime, unsigned int cond, int var, snd_pcm_hw_rule_func_t func, void *private, int dep, …); Arguments runtime the pcm runtime instance cond condition bits var the variable to evaluate func the evaluation function private the private data pointer passed to function dep the dependent variables … variable…
snd_pcm_hw_param_value – return params field var value Synopsis int snd_pcm_hw_param_value(const struct snd_pcm_hw_params *params, snd_pcm_hw_param_t var, int *dir); Arguments params the hw_params instance var parameter to retrieve dir pointer to the direction (-1,0,1) or NULL Return The value for field var if it’s fixed in configuration space defined by params. –EINVAL otherwise. Copyright