For Spreadtrum audio platform driver, it need allocate a larger DMA buffer
dynamically to copy audio data between userspace and kernel space, but that
will increase the risk of memory allocation failure especially the system
is under heavy load situation.
To make sure the audio can work in this scenario, we usually reserve one
region of memory to be used as a shared pool of DMA buffers for the
platform component. So add of_reserved_mem_device_init_by_idx() function
to initialize the shared pool of DMA buffers to be used by the platform
component.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
We use 2-stage DMA mode to support Spreadtrum audio compress offload,
which means we use one DMA source channel to transfer data from IRAM
buffer to the DSP fifo to do decoding/encoding, once IRAM buffer is
empty by transferring done, another DMA destination channel will be
triggered automatically to start to transfer data from DDR buffer to
the IRAM buffer. This can reduce the AP subsystem wakeup times to save
power.
Co-developed-by: Yintang Ren <yintang.ren@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
The Spreadtrum DMA engine uses the link-list mode to support audio playback
or capture, thus this patch adds audio DMA platform support for CPU DAI to
trigger DMA link-list transfer.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Baolin Wang