ASoC: AMD: Restore PME_EN state at Power On

PME_EN state needs to restored to the value set by fmw.
For the devices which are not using I2S wake event which gets
enabled by PME_EN bit, keeping PME_EN enabled burns considerable amount
of power as it blocks low power state.
For the devices using I2S wake event, PME_EN gets enabled in fmw and the
state should be maintained after ACP Power On.
Signed-off-by: Akshu Agrawal <akshu.agrawal@amd.com>
Link: https://lore.kernel.org/r/20200724195600.11798-1-akshu.agrawal@amd.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/amd/raven/pci-acp3x.c

@@ -19,10 +19,12 @@ struct acp3x_dev_data {
 	bool acp3x_audio_mode;
 	struct resource *res;
 	struct platform_device *pdev[ACP3x_DEVS];
+	u32 pme_en;
 };
 
-static int acp3x_power_on(void __iomem *acp3x_base)
+static int acp3x_power_on(struct acp3x_dev_data *adata)
 {
+	void __iomem *acp3x_base = adata->acp3x_base;
 	u32 val;
 	int timeout;
 
@@ -39,10 +41,10 @@ static int acp3x_power_on(void __iomem *acp3x_base)
 	while (++timeout < 500) {
 		val = rv_readl(acp3x_base + mmACP_PGFSM_STATUS);
 		if (!val) {
-			/* Set PME_EN as after ACP power On,
-			 * PME_EN gets cleared
+			/* ACP power On clears PME_EN.
+			 * Restore the value to its prior state
 			 */
-			rv_writel(0x1, acp3x_base + mmACP_PME_EN);
+			rv_writel(adata->pme_en, acp3x_base + mmACP_PME_EN);
 			return 0;
 		}
 		udelay(1);
@@ -74,12 +76,13 @@ static int acp3x_reset(void __iomem *acp3x_base)
 	return -ETIMEDOUT;
 }
 
-static int acp3x_init(void __iomem *acp3x_base)
+static int acp3x_init(struct acp3x_dev_data *adata)
 {
+	void __iomem *acp3x_base = adata->acp3x_base;
 	int ret;
 
 	/* power on */
-	ret = acp3x_power_on(acp3x_base);
+	ret = acp3x_power_on(adata);
 	if (ret) {
 		pr_err("ACP3x power on failed\n");
 		return ret;
@@ -151,7 +154,9 @@ static int snd_acp3x_probe(struct pci_dev *pci,
 	}
 	pci_set_master(pci);
 	pci_set_drvdata(pci, adata);
-	ret = acp3x_init(adata->acp3x_base);
+	/* Save ACP_PME_EN state */
+	adata->pme_en = rv_readl(adata->acp3x_base + mmACP_PME_EN);
+	ret = acp3x_init(adata);
 	if (ret)
 		goto disable_msi;
 
@@ -274,7 +279,7 @@ static int snd_acp3x_resume(struct device *dev)
 	struct acp3x_dev_data *adata;
 
 	adata = dev_get_drvdata(dev);
-	ret = acp3x_init(adata->acp3x_base);
+	ret = acp3x_init(adata);
 	if (ret) {
 		dev_err(dev, "ACP init failed\n");
 		return ret;