[PATCH 3/5] drm/i915/bxt: Added _DSM call to set HPD_CTL.

[Animesh Manna]

_DSM is added to program HPD_CTL(0x1094) register
of PMC from i915 driver which will be called
based on driver feature flag.

During S0ix display engine is completely powered down. Hot plug will be
missed by display HPD detection logic. GPIO unit detect any edge on HPD
pin and then triggers PMC->Punit to power up and restore display.
By programming PMC hpd control register we are enabling the manual
trigger from Punit which will be done by writing the PM interrupt register.

Note: Display engine continue to get HPD interrupt even after DC9 but
the system is in S0 state (VNN will be on).

v1: Initial version as RFC.

v2: Modified the commit message.

Signed-off-by: Animesh Manna <animesh.manna at intel.com>
---
 drivers/gpu/drm/i915/intel_acpi.c | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_acpi.c b/drivers/gpu/drm/i915/intel_acpi.c
index 5c49cef..e7d15720 100644
--- a/drivers/gpu/drm/i915/intel_acpi.c
+++ b/drivers/gpu/drm/i915/intel_acpi.c
@@ -10,6 +10,8 @@
 
 #define INTEL_DSM_REVISION_ID 1 /* For Calpella anyway... */
 #define INTEL_DSM_FN_PLATFORM_MUX_INFO 1 /* No args */
+#define INTEL_DSM_SET_HPD_WAKEUP 17
+#define HPD_WAKEUP_EN_VAL 0xFCF0
 
 static struct intel_dsm_priv {
 	acpi_handle dhandle;
@@ -118,6 +120,30 @@ static void intel_dsm_platform_mux_info(void)
 	ACPI_FREE(pkg);
 }
 
+static void intel_dsm_set_hpd_wakeup(const u8 *guid)
+{
+	union acpi_object *obj;
+	union acpi_object argv = {
+		.integer.type = ACPI_TYPE_INTEGER,
+		.integer.value = HPD_WAKEUP_EN_VAL,
+	};
+	union acpi_object argv4;
+
+	argv4.type = ACPI_TYPE_PACKAGE;
+	argv4.package.count = 1;
+	argv4.package.elements = &argv;
+
+	obj = acpi_evaluate_dsm(intel_dsm_priv.dhandle, guid,
+			INTEL_DSM_REVISION_ID, INTEL_DSM_SET_HPD_WAKEUP,
+			&argv4);
+
+	if (!obj)
+		DRM_DEBUG_DRIVER("failed to evaluate _DSM\n");
+
+	ACPI_FREE(obj);
+}
+
+
 static bool intel_dsm_pci_probe(struct pci_dev *pdev)
 {
 	acpi_handle dhandle;
@@ -131,11 +157,12 @@ static bool intel_dsm_pci_probe(struct pci_dev *pdev)
 	intel_dsm_priv.dhandle = dhandle;
 
 	if (IS_BROXTON(dev_priv)) {
-		union acpi_object *obj;
-
-		obj = acpi_evaluate_dsm(dhandle, intel_dsm_guid_bxt,
-					INTEL_DSM_REVISION_ID, 0, NULL);
-		if (!obj)
+		if (dev_priv->vbt.hpd_wakeup_enabled &&
+		    acpi_check_dsm(dhandle, intel_dsm_guid_bxt,
+				   INTEL_DSM_REVISION_ID,
+				   1 << INTEL_DSM_SET_HPD_WAKEUP))
+			intel_dsm_set_hpd_wakeup(intel_dsm_guid_bxt);
+		else
 			return false;
 	} else {
 		if (acpi_check_dsm(dhandle, intel_dsm_guid,
-- 
1.9.1