kcps: fix 0 module CPC case

If a module contains 0 as its CPC value, the consumption calculation
routine will assign a "safe" maximum value to keep the DSP running at
the maximum clock rate. This works when constructing a pipeline, but
when a pipeline is torn down, returning the maximum clock rate leads
to the clock being reduced to a small value. Fix this by detecting
such cases in pipeline termination code.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

src/audio/pipeline/pipeline-stream.c

@@ -344,11 +344,24 @@ static int pipeline_calc_cps_consumption(struct comp_dev *current,
 
 	if (cd->cpc == 0) {
 		/* Use maximum clock budget, assume 1ms chunk size */
-		ppl_data->kcps[comp_core] = CLK_MAX_CPU_HZ / 1000;
+		uint32_t core_kcps = core_kcps_get(comp_core);
+
+		if (!current->kcps_inc[comp_core]) {
+			current->kcps_inc[comp_core] = core_kcps;
+			ppl_data->kcps[comp_core] = CLK_MAX_CPU_HZ / 1000 - core_kcps;
+		} else {
+			ppl_data->kcps[comp_core] = core_kcps - current->kcps_inc[comp_core];
+			current->kcps_inc[comp_core] = 0;
+		}
 		tr_warn(pipe,
 			"0 CPS requested for module: %#x, core: %d using safe max KCPS: %u",
 			current->ipc_config.id, comp_core, ppl_data->kcps[comp_core]);
 
+		/*
+		 * This return code indicates to the caller, that the kcps calue
+		 * shouldn't be used for slowing down the clock when terminating
+		 * the pipeline
+		 */
 		return PPL_STATUS_PATH_STOP;
 	} else {
 		kcps = cd->cpc * 1000 / current->period;

src/include/sof/audio/component.h

@@ -604,6 +604,10 @@ struct comp_dev {
 #if CONFIG_PERFORMANCE_COUNTERS
 	struct perf_cnt_data pcd;
 #endif
+
+#if CONFIG_KCPS_DYNAMIC_CLOCK_CONTROL
+	int32_t kcps_inc[CONFIG_CORE_COUNT];
+#endif
 };
 
 /** @}*/

src/include/sof/audio/pipeline.h

@@ -123,7 +123,7 @@ struct pipeline_data {
 	int cmd;
 	uint32_t delay_ms;		/* between PRE_{START,RELEASE} and {START,RELEASE} */
 #if CONFIG_KCPS_DYNAMIC_CLOCK_CONTROL
-	uint32_t kcps[CONFIG_CORE_COUNT]; /**< the max count of KCPS */
+	int32_t kcps[CONFIG_CORE_COUNT]; /**< the max count of KCPS */
 #endif
 };