drm/nouveau/dp: fix support for dpms

SOR_PWR has no effect to power-off DP links, unlike other SOR protocols.

Instead, on the source side, we cut power to the lanes after having put
the sink into D3.  Link training takes care of everything required to
bring it back again.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_connector.c

@@ -76,7 +76,8 @@ find_encoder(struct drm_connector *connector, int type)
 			continue;
 		nv_encoder = nouveau_encoder(obj_to_encoder(obj));
 
-		if (type == DCB_OUTPUT_ANY || nv_encoder->dcb->type == type)
+		if (type == DCB_OUTPUT_ANY ||
+		    (nv_encoder->dcb && nv_encoder->dcb->type == type))
 			return nv_encoder;
 	}
 
@@ -914,6 +915,40 @@ nouveau_connector_funcs_lvds = {
 	.force = nouveau_connector_force
 };
 
+static void
+nouveau_connector_dp_dpms(struct drm_connector *connector, int mode)
+{
+	struct nouveau_encoder *nv_encoder = NULL;
+
+	if (connector->encoder)
+		nv_encoder = nouveau_encoder(connector->encoder);
+	if (nv_encoder && nv_encoder->dcb &&
+	    nv_encoder->dcb->type == DCB_OUTPUT_DP) {
+		if (mode == DRM_MODE_DPMS_ON) {
+			u8 data = DP_SET_POWER_D0;
+			nv_wraux(nv_encoder->i2c, DP_SET_POWER, &data, 1);
+			usleep_range(1000, 2000);
+		} else {
+			u8 data = DP_SET_POWER_D3;
+			nv_wraux(nv_encoder->i2c, DP_SET_POWER, &data, 1);
+		}
+	}
+
+	drm_helper_connector_dpms(connector, mode);
+}
+
+static const struct drm_connector_funcs
+nouveau_connector_funcs_dp = {
+	.dpms = nouveau_connector_dp_dpms,
+	.save = NULL,
+	.restore = NULL,
+	.detect = nouveau_connector_detect,
+	.destroy = nouveau_connector_destroy,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.set_property = nouveau_connector_set_property,
+	.force = nouveau_connector_force
+};
+
 static void
 nouveau_connector_hotplug_work(struct work_struct *work)
 {
@@ -1122,7 +1157,7 @@ nouveau_connector_create(struct drm_device *dev, int index)
 			return ERR_PTR(ret);
 		}
 
-		funcs = &nouveau_connector_funcs;
+		funcs = &nouveau_connector_funcs_dp;
 		break;
 	default:
 		funcs = &nouveau_connector_funcs;

drivers/gpu/drm/nouveau/nv50_display.c

@@ -26,6 +26,7 @@
 
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_dp_helper.h>
 
 #include "nouveau_drm.h"
 #include "nouveau_dma.h"
@@ -1722,7 +1723,7 @@ nv50_sor_dpms(struct drm_encoder *encoder, int mode)
 	struct drm_device *dev = encoder->dev;
 	struct nv50_disp *disp = nv50_disp(dev);
 	struct drm_encoder *partner;
-	int or = nv_encoder->or;
+	u32 mthd;
 
 	nv_encoder->last_dpms = mode;
 
@@ -1740,7 +1741,17 @@ nv50_sor_dpms(struct drm_encoder *encoder, int mode)
 		}
 	}
 
-	nv_call(disp->core, NV50_DISP_SOR_PWR + or, (mode == DRM_MODE_DPMS_ON));
+	mthd  = (ffs(nv_encoder->dcb->sorconf.link) - 1) << 2;
+	mthd |= nv_encoder->or;
+
+	if (nv_encoder->dcb->type == DCB_OUTPUT_DP) {
+		nv_call(disp->core, NV50_DISP_SOR_PWR | mthd, 1);
+		mthd |= NV94_DISP_SOR_DP_PWR;
+	} else {
+		mthd |= NV50_DISP_SOR_PWR;
+	}
+
+	nv_call(disp->core, mthd, (mode == DRM_MODE_DPMS_ON));
 }
 
 static bool