drm/nouveau/disp: add method to trigger DP link retrain

This moves control of link retraining in response to HPD IRQ to the
KMS driver's HPD IRQ handler.

NVKM still handles checking link status for the moment, this can be
moved to the KMS driver when it takes explicit control of link rate
selection.

v2:
- skip source config on retrain (fixes some retrain failures)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

2 files changed, 93 insertions, 60 deletions

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
index 92c9faecffae..730c3a6f3362 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
@@ -274,71 +274,18 @@ nvkm_dp_train_cr(struct lt_state *lt)
 }
 
 static int
-nvkm_dp_train_links(struct nvkm_outp *outp, int rate)
+nvkm_dp_train_link(struct nvkm_outp *outp, int rate)
 {
 	struct nvkm_ior *ior = outp->ior;
-	struct nvkm_disp *disp = outp->disp;
-	struct nvkm_subdev *subdev = &disp->engine.subdev;
-	struct nvkm_bios *bios = subdev->device->bios;
 	struct lt_state lt = {
 		.outp = outp,
+		.pc2 = outp->dp.dpcd[DPCD_RC02] & DPCD_RC02_TPS3_SUPPORTED,
 	};
-	u32 lnkcmp;
 	u8 sink[2], data;
 	int ret;
 
 	OUTP_DBG(outp, "training %dx%02x", ior->dp.nr, ior->dp.bw);
 
-	/* Intersect misc. capabilities of the OR and sink. */
-	if (disp->engine.subdev.device->chipset < 0x110)
-		outp->dp.dpcd[DPCD_RC03] &= ~DPCD_RC03_TPS4_SUPPORTED;
-	if (disp->engine.subdev.device->chipset < 0xd0)
-		outp->dp.dpcd[DPCD_RC02] &= ~DPCD_RC02_TPS3_SUPPORTED;
-	lt.pc2 = outp->dp.dpcd[DPCD_RC02] & DPCD_RC02_TPS3_SUPPORTED;
-
-	if (AMPERE_IED_HACK(disp) && (lnkcmp = lt.outp->dp.info.script[0])) {
-		/* Execute BeforeLinkTraining script from DP Info table. */
-		while (ior->dp.bw < nvbios_rd08(bios, lnkcmp))
-			lnkcmp += 3;
-		lnkcmp = nvbios_rd16(bios, lnkcmp + 1);
-
-		nvbios_init(&outp->disp->engine.subdev, lnkcmp,
-			init.outp = &outp->info;
-			init.or   = ior->id;
-			init.link = ior->asy.link;
-		);
-	}
-
-	/* Set desired link configuration on the source. */
-	if ((lnkcmp = lt.outp->dp.info.lnkcmp)) {
-		if (outp->dp.version < 0x30) {
-			while ((ior->dp.bw * 2700) < nvbios_rd16(bios, lnkcmp))
-				lnkcmp += 4;
-			lnkcmp = nvbios_rd16(bios, lnkcmp + 2);
-		} else {
-			while (ior->dp.bw < nvbios_rd08(bios, lnkcmp))
-				lnkcmp += 3;
-			lnkcmp = nvbios_rd16(bios, lnkcmp + 1);
-		}
-
-		nvbios_init(subdev, lnkcmp,
-			init.outp = &outp->info;
-			init.or   = ior->id;
-			init.link = ior->asy.link;
-		);
-	}
-
-	ret = ior->func->dp->links(ior, outp->dp.aux);
-	if (ret) {
-		if (ret < 0) {
-			OUTP_ERR(outp, "train failed with %d", ret);
-			return ret;
-		}
-		return 0;
-	}
-
-	ior->func->dp->power(ior, ior->dp.nr);
-
 	/* Select LTTPR non-transparent mode if we have a valid configuration,
 	 * use transparent mode otherwise.
 	 */
@@ -393,6 +340,71 @@ nvkm_dp_train_links(struct nvkm_outp *outp, int rate)
 	return ret;
 }
 
+static int
+nvkm_dp_train_links(struct nvkm_outp *outp, int rate)
+{
+	struct nvkm_ior *ior = outp->ior;
+	struct nvkm_disp *disp = outp->disp;
+	struct nvkm_subdev *subdev = &disp->engine.subdev;
+	struct nvkm_bios *bios = subdev->device->bios;
+	u32 lnkcmp;
+	int ret;
+
+	OUTP_DBG(outp, "programming link for %dx%02x", ior->dp.nr, ior->dp.bw);
+
+	/* Intersect misc. capabilities of the OR and sink. */
+	if (disp->engine.subdev.device->chipset < 0x110)
+		outp->dp.dpcd[DPCD_RC03] &= ~DPCD_RC03_TPS4_SUPPORTED;
+	if (disp->engine.subdev.device->chipset < 0xd0)
+		outp->dp.dpcd[DPCD_RC02] &= ~DPCD_RC02_TPS3_SUPPORTED;
+
+	if (AMPERE_IED_HACK(disp) && (lnkcmp = outp->dp.info.script[0])) {
+		/* Execute BeforeLinkTraining script from DP Info table. */
+		while (ior->dp.bw < nvbios_rd08(bios, lnkcmp))
+			lnkcmp += 3;
+		lnkcmp = nvbios_rd16(bios, lnkcmp + 1);
+
+		nvbios_init(&outp->disp->engine.subdev, lnkcmp,
+			init.outp = &outp->info;
+			init.or   = ior->id;
+			init.link = ior->asy.link;
+		);
+	}
+
+	/* Set desired link configuration on the source. */
+	if ((lnkcmp = outp->dp.info.lnkcmp)) {
+		if (outp->dp.version < 0x30) {
+			while ((ior->dp.bw * 2700) < nvbios_rd16(bios, lnkcmp))
+				lnkcmp += 4;
+			lnkcmp = nvbios_rd16(bios, lnkcmp + 2);
+		} else {
+			while (ior->dp.bw < nvbios_rd08(bios, lnkcmp))
+				lnkcmp += 3;
+			lnkcmp = nvbios_rd16(bios, lnkcmp + 1);
+		}
+
+		nvbios_init(subdev, lnkcmp,
+			init.outp = &outp->info;
+			init.or   = ior->id;
+			init.link = ior->asy.link;
+		);
+	}
+
+	ret = ior->func->dp->links(ior, outp->dp.aux);
+	if (ret) {
+		if (ret < 0) {
+			OUTP_ERR(outp, "train failed with %d", ret);
+			return ret;
+		}
+		return 0;
+	}
+
+	ior->func->dp->power(ior, ior->dp.nr);
+
+	/* Attempt to train the link in this configuration. */
+	return nvkm_dp_train_link(outp, rate);
+}
+
 static void
 nvkm_dp_train_fini(struct nvkm_outp *outp)
 {
@@ -439,6 +451,16 @@ nvkm_dp_train(struct nvkm_outp *outp, u32 dataKBps)
 	int ret = -EINVAL, nr, rate;
 	u8  pwr;
 
+	/* Retraining link?  Skip source configuration, it can mess up the active modeset. */
+	if (atomic_read(&outp->dp.lt.done)) {
+		for (rate = 0; rate < outp->dp.rates; rate++) {
+			if (outp->dp.rate[rate].rate == ior->dp.bw * 27000)
+				return nvkm_dp_train_link(outp, ret);
+		}
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
 	/* Ensure sink is not in a low-power state. */
 	if (!nvkm_rdaux(outp->dp.aux, DPCD_SC00, &pwr, 1)) {
 		if ((pwr & DPCD_SC00_SET_POWER) != DPCD_SC00_SET_POWER_D0) {
@@ -726,12 +748,8 @@ nvkm_dp_hpd(struct nvkm_notify *notify)
 	struct nvif_notify_conn_rep_v0 rep = {};
 
 	OUTP_DBG(outp, "HPD: %d", line->mask);
-	if (line->mask & NVKM_I2C_IRQ) {
-		if (atomic_read(&outp->dp.lt.done))
-			outp->func->acquire(outp);
+	if (line->mask & NVKM_I2C_IRQ)
 		rep.mask |= NVIF_NOTIFY_CONN_V0_IRQ;
-	}
-
 	if (line->mask & NVKM_I2C_UNPLUG)
 		rep.mask |= NVIF_NOTIFY_CONN_V0_UNPLUG;
 	if (line->mask & NVKM_I2C_PLUG)
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
index 3bfc3e39778e..e12a31d428d6 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
@@ -28,6 +28,20 @@
 #include <nvif/if0012.h>
 
 static int
+nvkm_uoutp_mthd_dp_retrain(struct nvkm_outp *outp, void *argv, u32 argc)
+{
+	union nvif_outp_dp_retrain_args *args = argv;
+
+	if (argc != sizeof(args->vn))
+		return -ENOSYS;
+
+	if (!atomic_read(&outp->dp.lt.done))
+		return 0;
+
+	return outp->func->acquire(outp);
+}
+
+static int
 nvkm_uoutp_mthd_dp_aux_pwr(struct nvkm_outp *outp, void *argv, u32 argc)
 {
 	union nvif_outp_dp_aux_pwr_args *args = argv;
@@ -251,6 +265,7 @@ nvkm_uoutp_mthd_acquired(struct nvkm_outp *outp, u32 mthd, void *argv, u32 argc)
 	case NVIF_OUTP_V0_RELEASE    : return nvkm_uoutp_mthd_release    (outp, argv, argc);
 	case NVIF_OUTP_V0_INFOFRAME  : return nvkm_uoutp_mthd_infoframe  (outp, argv, argc);
 	case NVIF_OUTP_V0_HDA_ELD    : return nvkm_uoutp_mthd_hda_eld    (outp, argv, argc);
+	case NVIF_OUTP_V0_DP_RETRAIN : return nvkm_uoutp_mthd_dp_retrain (outp, argv, argc);
 	default:
 		break;
 	}