ASoC: Intel: Skylake: Disable SRAM Retention before D3

SW needs to set the PGCTL.LSRMD = 1 to disable LPSRAM retention
feature,otherwise it may lead to SRAM ECC Errors.
Signed-off-by: Dharageswari R <dharageswari.r@intel.com>
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/skylake/skl.c

@@ -186,6 +186,7 @@ static int _skl_suspend(struct hdac_ext_bus *ebus)
 {
 	struct skl *skl = ebus_to_skl(ebus);
 	struct hdac_bus *bus = ebus_to_hbus(ebus);
+	struct pci_dev *pci = to_pci_dev(bus->dev);
 	int ret;
 
 	snd_hdac_ext_bus_link_power_down_all(ebus);
@@ -195,6 +196,8 @@ static int _skl_suspend(struct hdac_ext_bus *ebus)
 		return ret;
 
 	snd_hdac_bus_stop_chip(bus);
+	update_pci_dword(pci, AZX_PCIREG_PGCTL,
+		AZX_PGCTL_LSRMD_MASK, AZX_PGCTL_LSRMD_MASK);
 	skl_enable_miscbdcge(bus->dev, false);
 	snd_hdac_bus_enter_link_reset(bus);
 	skl_enable_miscbdcge(bus->dev, true);

sound/soc/intel/skylake/skl.h

@@ -48,6 +48,8 @@
 #define AZX_REG_VS_SDXEFIFOS_XBASE	0x1094
 #define AZX_REG_VS_SDXEFIFOS_XINTERVAL	0x20
 
+#define AZX_PCIREG_PGCTL		0x44
+#define AZX_PGCTL_LSRMD_MASK		(1 << 4)
 #define AZX_PCIREG_CGCTL		0x48
 #define AZX_CGCTL_MISCBDCGE_MASK	(1 << 6)