[PATCH 4.4 194/342] drm/nouveau/disp/dp: ensure sink is powered up before attempting link training
From: Greg Kroah-Hartman
Date: Tue Mar 01 2016 - 19:48:51 EST
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ben Skeggs <bskeggs@xxxxxxxxxx>
commit 95664e66fad964c3dd7945d6edfb1d0931844664 upstream.
This can happen under some annoying circumstances, and is a quick fix
until more substantial changes can be made.
Fixed eDP mode changes on (at least) the Lenovo P50.
Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nvkm/engine/disp/dport.c | 10 ++++++++++
drivers/gpu/drm/nouveau/nvkm/engine/disp/dport.h | 6 ++++++
2 files changed, 16 insertions(+)
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dport.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dport.c
@@ -328,6 +328,7 @@ nvkm_dp_train(struct work_struct *w)
.outp = outp,
}, *dp = &_dp;
u32 datarate = 0;
+ u8 pwr;
int ret;
if (!outp->base.info.location && disp->func->sor.magic)
@@ -355,6 +356,15 @@ nvkm_dp_train(struct work_struct *w)
/* disable link interrupt handling during link training */
nvkm_notify_put(&outp->irq);
+ /* ensure sink is not in a low-power state */
+ if (!nvkm_rdaux(outp->aux, DPCD_SC00, &pwr, 1)) {
+ if ((pwr & DPCD_SC00_SET_POWER) != DPCD_SC00_SET_POWER_D0) {
+ pwr &= ~DPCD_SC00_SET_POWER;
+ pwr |= DPCD_SC00_SET_POWER_D0;
+ nvkm_wraux(outp->aux, DPCD_SC00, &pwr, 1);
+ }
+ }
+
/* enable down-spreading and execute pre-train script from vbios */
dp_link_train_init(dp, outp->dpcd[3] & 0x01);
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dport.h
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dport.h
@@ -71,5 +71,11 @@
#define DPCD_LS0C_LANE1_POST_CURSOR2 0x0c
#define DPCD_LS0C_LANE0_POST_CURSOR2 0x03
+/* DPCD Sink Control */
+#define DPCD_SC00 0x00600
+#define DPCD_SC00_SET_POWER 0x03
+#define DPCD_SC00_SET_POWER_D0 0x01
+#define DPCD_SC00_SET_POWER_D3 0x03
+
void nvkm_dp_train(struct work_struct *);
#endif