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
snd_pcm_hw_param_last – refine config space and return maximum value Synopsis int snd_pcm_hw_param_last(struct snd_pcm_substream *pcm, struct snd_pcm_hw_params *params, snd_pcm_hw_param_t var, int *dir); Arguments pcm PCM instance params the hw_params instance var parameter to retrieve dir pointer to the direction (-1,0,1) or NULL Description Inside configuration space defined by params remove from var all values < maximum….
snd_pcm_hw_param_first – refine config space and return minimum value Synopsis int snd_pcm_hw_param_first(struct snd_pcm_substream *pcm, struct snd_pcm_hw_params *params, snd_pcm_hw_param_t var, int *dir); Arguments pcm PCM instance params the hw_params instance var parameter to retrieve dir pointer to the direction (-1,0,1) or NULL Description Inside configuration space defined by params remove from var all values > minimum….
snd_pcm_hw_constraint_step – add a hw constraint step rule Synopsis int snd_pcm_hw_constraint_step(struct snd_pcm_runtime *runtime, unsigned int cond, snd_pcm_hw_param_t var, unsigned long step); Arguments runtime PCM runtime instance cond condition bits var hw_params variable to apply the step constraint step step size Return Zero if successful, or a negative error code on failure. Copyright
snd_pcm_hw_constraint_single – Constrain parameter to a single value Synopsis int snd_pcm_hw_constraint_single(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var, unsigned int val); Arguments runtime PCM runtime instance var The hw_params variable to constrain val The value to constrain to Return Positive if the value is changed, zero if it’s not changed, or a negative error code. Copyright
snd_pcm_hw_constraint_ratnums – apply ratnums constraint to a parameter Synopsis int snd_pcm_hw_constraint_ratnums(struct snd_pcm_runtime *runtime, unsigned int cond, snd_pcm_hw_param_t var, const struct snd_pcm_hw_constraint_ratnums *r); Arguments runtime PCM runtime instance cond condition bits var hw_params variable to apply the ratnums constraint r struct snd_ratnums constriants Return Zero if successful, or a negative error code on failure. Copyright
snd_pcm_hw_constraint_ratdens – apply ratdens constraint to a parameter Synopsis int snd_pcm_hw_constraint_ratdens(struct snd_pcm_runtime *runtime, unsigned int cond, snd_pcm_hw_param_t var, const struct snd_pcm_hw_constraint_ratdens *r); Arguments runtime PCM runtime instance cond condition bits var hw_params variable to apply the ratdens constraint r struct snd_ratdens constriants Return Zero if successful, or a negative error code on failure. Copyright
snd_pcm_hw_constraint_ranges – apply list of range constraints to a parameter Synopsis int snd_pcm_hw_constraint_ranges(struct snd_pcm_runtime *runtime, unsigned int cond, snd_pcm_hw_param_t var, const struct snd_pcm_hw_constraint_ranges *r); Arguments runtime PCM runtime instance cond condition bits var hw_params variable to apply the list of range constraints r ranges Description Apply the list of range constraints to an interval parameter….
snd_pcm_hw_constraint_pow2 – add a hw constraint power-of-2 rule Synopsis int snd_pcm_hw_constraint_pow2(struct snd_pcm_runtime *runtime, unsigned int cond, snd_pcm_hw_param_t var); Arguments runtime PCM runtime instance cond condition bits var hw_params variable to apply the power-of-2 constraint Return Zero if successful, or a negative error code on failure. Copyright