ASoC: SOF: ipc4-topology: Add module parameter to ignore the CPC value

Add a new module parameter ipc4_ignore_cpc which can be used to force the
kernel to ignore the queried CPC value for all firmware modules and use 0
instead.

The CPC lookup is still done to report missing configurations and the
debug print is going to be different to be explicit that the CPC is ignored
and what was the value we would have used.

The CPC value is sent to the firmware with the MOD_INIT_INSTANCE message
and it is used by the firmware as a parameter for clock scaling.

The flag is intended to be used only when there is a need to validate the
firmware behavior regarding to clock scaling since the 0 CPC value will
force the DSP to run in full speed, disabling the scaling and provides
additional counter point to rule out clock management related issues.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20230822065419.24374-1-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/ipc4-topology.c

@@ -17,6 +17,19 @@
 #include "ipc4-topology.h"
 #include "ops.h"
 
+/*
+ * The ignore_cpc flag can be used to ignore the CPC value for all modules by
+ * using 0 instead.
+ * The CPC is sent to the firmware along with the SOF_IPC4_MOD_INIT_INSTANCE
+ * message and it is used for clock scaling.
+ * 0 as CPC value will instruct the firmware to use maximum frequency, thus
+ * deactivating the clock scaling.
+ */
+static bool ignore_cpc;
+module_param_named(ipc4_ignore_cpc, ignore_cpc, bool, 0444);
+MODULE_PARM_DESC(ipc4_ignore_cpc,
+		 "Ignore CPC values. This option will disable clock scaling in firmware.");
+
 #define SOF_IPC4_GAIN_PARAM_ID  0
 #define SOF_IPC4_TPLG_ABI_SIZE 6
 #define SOF_IPC4_CHAIN_DMA_BUF_SIZE_MS 2
@@ -970,9 +983,16 @@ sof_ipc4_update_resource_usage(struct snd_sof_dev *sdev, struct snd_sof_widget *
 	/* Update base_config->cpc from the module manifest */
 	sof_ipc4_update_cpc_from_manifest(sdev, fw_module, base_config);
 
-	dev_dbg(sdev->dev, "%s: ibs / obs / cpc: %u / %u / %u\n",
-		swidget->widget->name, base_config->ibs, base_config->obs,
-		base_config->cpc);
+	if (ignore_cpc) {
+		dev_dbg(sdev->dev, "%s: ibs / obs: %u / %u, forcing cpc to 0 from %u\n",
+			swidget->widget->name, base_config->ibs, base_config->obs,
+			base_config->cpc);
+		base_config->cpc = 0;
+	} else {
+		dev_dbg(sdev->dev, "%s: ibs / obs / cpc: %u / %u / %u\n",
+			swidget->widget->name, base_config->ibs, base_config->obs,
+			base_config->cpc);
+	}
 }
 
 static int sof_ipc4_widget_assign_instance_id(struct snd_sof_dev *sdev,