ASoC: Intel: Skylake: Disable clock and power gating during FW/LIB download

In order to achieve better DMA performance and reduce download time for
firmware and library, it is recommended to disable dynamic clock and
power gating. In some scenarios, DMA may wait to accumulate more data and
last chunk of data never gets completed if dynamic clock and power
gating is kept enabled.

This patch adds support to disable/enable dynamic clock and power gating
and use it during firmware and library download.

Signed-off-by: Rakesh Ughreja <rakesh.a.ughreja@intel.com>
Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Signed-off-by: Guneshwor Singh <guneshwor.o.singh@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/skylake/skl-messages.c

@@ -417,11 +417,16 @@ int skl_resume_dsp(struct skl *skl)
 	if (skl->skl_sst->is_first_boot == true)
 		return 0;
 
-	/* disable dynamic clock gating during fw and lib download */
+	/*
+	 * Disable dynamic clock and power gating during firmware
+	 * and library download
+	 */
 	ctx->enable_miscbdcge(ctx->dev, false);
+	ctx->clock_power_gating(ctx->dev, false);
 
 	ret = skl_dsp_wake(ctx->dsp);
 	ctx->enable_miscbdcge(ctx->dev, true);
+	ctx->clock_power_gating(ctx->dev, true);
 	if (ret < 0)
 		return ret;
 

sound/soc/intel/skylake/skl-pcm.c

@@ -1356,11 +1356,16 @@ static int skl_platform_soc_probe(struct snd_soc_component *component)
 			return -EIO;
 		}
 
-		/* disable dynamic clock gating during fw and lib download */
+		/*
+		 * Disable dynamic clock and power gating during firmware
+		 * and library download
+		 */
 		skl->skl_sst->enable_miscbdcge(component->dev, false);
+		skl->skl_sst->clock_power_gating(component->dev, false);
 
 		ret = ops->init_fw(component->dev, skl->skl_sst);
 		skl->skl_sst->enable_miscbdcge(component->dev, true);
+		skl->skl_sst->clock_power_gating(component->dev, true);
 		if (ret < 0) {
 			dev_err(component->dev, "Failed to boot first fw: %d\n", ret);
 			return ret;

sound/soc/intel/skylake/skl-sst-ipc.h

@@ -118,6 +118,9 @@ struct skl_sst {
 	struct skl_d0i3_data d0i3;
 
 	const struct skl_dsp_ops *dsp_ops;
+
+	/* Callback to update dynamic clock and power gating registers */
+	void (*clock_power_gating)(struct device *dev, bool enable);
 };
 
 struct skl_ipc_init_instance_msg {

sound/soc/intel/skylake/skl.c

@@ -94,6 +94,32 @@ static void skl_enable_miscbdcge(struct device *dev, bool enable)
 	update_pci_dword(pci, AZX_PCIREG_CGCTL, AZX_CGCTL_MISCBDCGE_MASK, val);
 }
 
+/**
+ * skl_clock_power_gating: Enable/Disable clock and power gating
+ *
+ * @dev: Device pointer
+ * @enable: Enable/Disable flag
+ */
+static void skl_clock_power_gating(struct device *dev, bool enable)
+{
+	struct pci_dev *pci = to_pci_dev(dev);
+	struct hdac_ext_bus *ebus = pci_get_drvdata(pci);
+	struct hdac_bus *bus = ebus_to_hbus(ebus);
+	u32 val;
+
+	/* Update PDCGE bit of CGCTL register */
+	val = enable ? AZX_CGCTL_ADSPDCGE : 0;
+	update_pci_dword(pci, AZX_PCIREG_CGCTL, AZX_CGCTL_ADSPDCGE, val);
+
+	/* Update L1SEN bit of EM2 register */
+	val = enable ? AZX_REG_VS_EM2_L1SEN : 0;
+	snd_hdac_chip_updatel(bus, VS_EM2, AZX_REG_VS_EM2_L1SEN, val);
+
+	/* Update ADSPPGD bit of PGCTL register */
+	val = enable ? 0 : AZX_PGCTL_ADSPPGD;
+	update_pci_dword(pci, AZX_PCIREG_PGCTL, AZX_PGCTL_ADSPPGD, val);
+}
+
 /*
  * While performing reset, controller may not come back properly causing
  * issues, so recommendation is to set CGCTL.MISCBDCGE to 0 then do reset
@@ -916,6 +942,7 @@ static int skl_probe(struct pci_dev *pci,
 			goto out_nhlt_free;
 		}
 		skl->skl_sst->enable_miscbdcge = skl_enable_miscbdcge;
+		skl->skl_sst->clock_power_gating = skl_clock_power_gating;
 	}
 	if (bus->mlcap)
 		snd_hdac_ext_bus_get_ml_capabilities(ebus);

sound/soc/intel/skylake/skl.h

@@ -33,8 +33,10 @@
 
 #define AZX_PCIREG_PGCTL		0x44
 #define AZX_PGCTL_LSRMD_MASK		(1 << 4)
+#define AZX_PGCTL_ADSPPGD		BIT(2)
 #define AZX_PCIREG_CGCTL		0x48
 #define AZX_CGCTL_MISCBDCGE_MASK	(1 << 6)
+#define AZX_CGCTL_ADSPDCGE		BIT(1)
 /* D0I3C Register fields */
 #define AZX_REG_VS_D0I3C_CIP      0x1 /* Command in progress */
 #define AZX_REG_VS_D0I3C_I3       0x4 /* D0i3 enable */
@@ -43,6 +45,8 @@
 #define DMA_TRANSMITION_START	2
 #define DMA_TRANSMITION_STOP	3
 
+#define AZX_REG_VS_EM2_L1SEN		BIT(13)
+
 struct skl_dsp_resource {
 	u32 max_mcps;
 	u32 max_mem;