Hi
On Fri, 13 Nov 2009 11:39:47 -0600 Jane Wang jwang@ti.com wrote:
McBSP fucntional clock is not disabled when suspend is triggerd which prevents PER domain entering target low-power state. To fix the problem:
Disable/enable McBSP functional clock for suspend/resume.
In addition, reconfigure McBSP, this is needed when systerm comes out of OFF state.
...
--- a/arch/arm/plat-omap/include/mach/mcbsp.h +++ b/arch/arm/plat-omap/include/mach/mcbsp.h @@ -440,6 +440,8 @@ static inline int omap_mcbsp_get_dma_op_mode(unsigned int id) { return 0; } #endif int omap_mcbsp_request(unsigned int id); void omap_mcbsp_free(unsigned int id); +void omap_mcbsp_disable_fclk(unsigned int id); +void omap_mcbsp_enable_fclk(unsigned int id);
...
--- a/sound/soc/omap/omap-mcbsp.c +++ b/sound/soc/omap/omap-mcbsp.c @@ -229,18 +229,28 @@ static int omap_mcbsp_dai_trigger(struct snd_pcm_substream *substream, int cmd,
switch (cmd) { case SNDRV_PCM_TRIGGER_START:
- case SNDRV_PCM_TRIGGER_RESUME: case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: mcbsp_data->active++; omap_mcbsp_start(mcbsp_data->bus_id, play, !play); break;
- case SNDRV_PCM_TRIGGER_RESUME:
mcbsp_data->active++;omap_mcbsp_enable_fclk(mcbsp_data->bus_id);omap_mcbsp_config(mcbsp_data->bus_id,&mcbsp_data->regs);omap_mcbsp_start(mcbsp_data->bus_id, play, !play);break;
For me this looks more like a simple workaround for the audio case than comprehensive implementation to McBSP OFF mode context save/restore. My thoughts:
1. McBSP clock management partially moved out of low-level driver 2. McBSP client must do the context restore
I do know that arch/arm/plat-omap/mcbsp.c enables the clocks in omap_mcbsp_request, I don't know do some API or feature there really require clocks (or McBSP itself) to be active just after the request time but I would look that path instead (even it is more complicated).
If no API or feature would require active McBSP block before the omap_mcbsp_start call, then the clock management could be done inside the omap_mcbsp_start/-stop functions.
Also context save/restore operations belongs more to PM callbacks of .../plat-omap/mcbsp.c. Or probably that can be done also dynamically inside the omap_mcbsp_start/-stop for keeping the whole McBSP shutdown whenever it is idle.
I think it's worth to look McBSP register cache concept [1] from Janusz Krzysztofik would it help all of this context save/restore operations.