Requesting an mailbox channel will call mailbox's startup function. startup function calls pm_runtime_get_sync which increments device usage count and will keep the device active. Specifically, mailbox clock will be always ON when a mailbox channel is requested.
For this, reason we introduce a way to request/free IMX DSP channels on demand to save power when the channels are not used. First two patches are doing code refactoring preparing the path for 3rd patch which exports functions for on demand channel request/free Daniel Baluta (3): firmware: imx: Introduce imx_dsp_setup_channels firmware: imx: Save channel name for further use firmware: imx-dsp: Export functions to request/free channels drivers/firmware/imx/imx-dsp.c | 72 ++++++++++++++++++++++++-------- include/linux/firmware/imx/dsp.h | 10 +++++ 2 files changed, 64 insertions(+), 18 deletions(-) -- 2.17.1