drm/nouveau/disp/dp: remove workqueue for link training

There haven't been any callers from an atomic context for a while now,
so let's remove the extra complexity.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/engine/disp/dport.c

@@ -319,9 +319,8 @@ static const struct dp_rates {
 };
 
 void
-nvkm_dp_train(struct work_struct *w)
+nvkm_dp_train(struct nvkm_output_dp *outp)
 {
-	struct nvkm_output_dp *outp = container_of(w, typeof(*outp), lt.work);
 	struct nv50_disp *disp = nv50_disp(outp->base.disp);
 	const struct dp_rates *cfg = nvkm_dp_rates;
 	struct dp_state _dp = {
@@ -353,9 +352,6 @@ nvkm_dp_train(struct work_struct *w)
 	}
 	cfg--;
 
-	/* 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) {
@@ -400,9 +396,6 @@ nvkm_dp_train(struct work_struct *w)
 
 	dp_link_train_fini(dp);
 
-	/* signal completion and enable link interrupt handling */
 	OUTP_DBG(&outp->base, "training complete");
 	atomic_set(&outp->lt.done, 1);
-	wake_up(&outp->lt.wait);
-	nvkm_notify_get(&outp->irq);
 }

drivers/gpu/drm/nouveau/nvkm/engine/disp/dport.h

 #ifndef __NVKM_DISP_DPORT_H__
 #define __NVKM_DISP_DPORT_H__
-#include <core/os.h>
+struct nvkm_output_dp;
 
 /* DPCD Receiver Capabilities */
 #define DPCD_RC00_DPCD_REV                                              0x00000
@@ -77,5 +77,5 @@
 #define DPCD_SC00_SET_POWER_D0                                             0x01
 #define DPCD_SC00_SET_POWER_D3                                             0x03
 
-void nvkm_dp_train(struct work_struct *);
+void nvkm_dp_train(struct nvkm_output_dp *);
 #endif

drivers/gpu/drm/nouveau/nvkm/engine/disp/gf119.c

@@ -314,7 +314,7 @@ gf119_disp_intr_unk2_2(struct nv50_disp *disp, int head)
 			break;
 		}
 
-		if (nvkm_output_dp_train(outp, pclk, true))
+		if (nvkm_output_dp_train(outp, pclk))
 			OUTP_ERR(outp, "link not trained before attach");
 	} else {
 		if (disp->func->sor.magic)

drivers/gpu/drm/nouveau/nvkm/engine/disp/nv50.c

@@ -779,7 +779,7 @@ nv50_disp_intr_unk20_2(struct nv50_disp *disp, int head)
 			break;
 		}
 
-		if (nvkm_output_dp_train(outp, datarate / soff, true))
+		if (nvkm_output_dp_train(outp, datarate / soff))
 			OUTP_ERR(outp, "link not trained before attach");
 	}
 

drivers/gpu/drm/nouveau/nvkm/engine/disp/outpdp.c

@@ -31,7 +31,7 @@
 #include <nvif/event.h>
 
 int
-nvkm_output_dp_train(struct nvkm_output *base, u32 datarate, bool wait)
+nvkm_output_dp_train(struct nvkm_output *base, u32 datarate)
 {
 	struct nvkm_output_dp *outp = nvkm_output_dp(base);
 	bool retrain = true;
@@ -39,6 +39,8 @@ nvkm_output_dp_train(struct nvkm_output *base, u32 datarate, bool wait)
 	u32 linkrate;
 	int ret, i;
 
+	mutex_lock(&outp->mutex);
+
 	/* check that the link is trained at a high enough rate */
 	ret = nvkm_rdaux(outp->aux, DPCD_LC00_LINK_BW_SET, link, 2);
 	if (ret) {
@@ -88,19 +90,10 @@ nvkm_output_dp_train(struct nvkm_output *base, u32 datarate, bool wait)
 			outp->dpcd[DPCD_RC02] =
 				outp->base.info.dpconf.link_nr;
 		}
-		atomic_set(&outp->lt.done, 0);
-		schedule_work(&outp->lt.work);
-	} else {
-		nvkm_notify_get(&outp->irq);
-	}
-
-	if (wait) {
-		if (!wait_event_timeout(outp->lt.wait,
-					atomic_read(&outp->lt.done),
-					msecs_to_jiffies(2000)))
-			ret = -ETIMEDOUT;
+		nvkm_dp_train(outp);
 	}
 
+	mutex_unlock(&outp->mutex);
 	return ret;
 }
 
@@ -118,7 +111,7 @@ nvkm_output_dp_enable(struct nvkm_output_dp *outp, bool enable)
 
 		if (!nvkm_rdaux(aux, DPCD_RC00_DPCD_REV, outp->dpcd,
 				sizeof(outp->dpcd))) {
-			nvkm_output_dp_train(&outp->base, 0, true);
+			nvkm_output_dp_train(&outp->base, 0);
 			return;
 		}
 	}
@@ -165,10 +158,10 @@ nvkm_output_dp_irq(struct nvkm_notify *notify)
 	};
 
 	OUTP_DBG(&outp->base, "IRQ: %d", line->mask);
-	nvkm_output_dp_train(&outp->base, 0, true);
+	nvkm_output_dp_train(&outp->base, 0);
 
 	nvkm_event_send(&disp->hpd, rep.mask, conn->index, &rep, sizeof(rep));
-	return NVKM_NOTIFY_DROP;
+	return NVKM_NOTIFY_KEEP;
 }
 
 static void
@@ -177,7 +170,6 @@ nvkm_output_dp_fini(struct nvkm_output *base)
 	struct nvkm_output_dp *outp = nvkm_output_dp(base);
 	nvkm_notify_put(&outp->hpd);
 	nvkm_notify_put(&outp->irq);
-	flush_work(&outp->lt.work);
 	nvkm_output_dp_enable(outp, false);
 }
 
@@ -187,6 +179,7 @@ nvkm_output_dp_init(struct nvkm_output *base)
 	struct nvkm_output_dp *outp = nvkm_output_dp(base);
 	nvkm_notify_put(&outp->base.conn->hpd);
 	nvkm_output_dp_enable(outp, true);
+	nvkm_notify_get(&outp->irq);
 	nvkm_notify_get(&outp->hpd);
 }
 
@@ -238,11 +231,6 @@ nvkm_output_dp_ctor(const struct nvkm_output_dp_func *func,
 	OUTP_DBG(&outp->base, "bios dp %02x %02x %02x %02x",
 		 outp->version, hdr, cnt, len);
 
-	/* link training */
-	INIT_WORK(&outp->lt.work, nvkm_dp_train);
-	init_waitqueue_head(&outp->lt.wait);
-	atomic_set(&outp->lt.done, 0);
-
 	/* link maintenance */
 	ret = nvkm_notify_init(NULL, &i2c->event, nvkm_output_dp_irq, true,
 			       &(struct nvkm_i2c_ntfy_req) {
@@ -257,6 +245,9 @@ nvkm_output_dp_ctor(const struct nvkm_output_dp_func *func,
 		return ret;
 	}
 
+	mutex_init(&outp->mutex);
+	atomic_set(&outp->lt.done, 0);
+
 	/* hotplug detect, replaces gpio-based mechanism with aux events */
 	ret = nvkm_notify_init(NULL, &i2c->event, nvkm_output_dp_hpd, true,
 			       &(struct nvkm_i2c_ntfy_req) {

drivers/gpu/drm/nouveau/nvkm/engine/disp/outpdp.h

@@ -29,9 +29,8 @@ struct nvkm_output_dp {
 	bool present;
 	u8 dpcd[16];
 
+	struct mutex mutex;
 	struct {
-		struct work_struct work;
-		wait_queue_head_t wait;
 		atomic_t done;
 	} lt;
 };
@@ -43,7 +42,7 @@ struct nvkm_output_dp_func {
 	int (*drv_ctl)(struct nvkm_output_dp *, int ln, int vs, int pe, int pc);
 };
 
-int nvkm_output_dp_train(struct nvkm_output *, u32 rate, bool wait);
+int nvkm_output_dp_train(struct nvkm_output *, u32 rate);
 
 int nvkm_output_dp_ctor(const struct nvkm_output_dp_func *, struct nvkm_disp *,
 			int index, struct dcb_output *, struct nvkm_i2c_aux *,

drivers/gpu/drm/nouveau/nvkm/engine/disp/rootnv50.c

@@ -173,7 +173,7 @@ nv50_disp_root_mthd_(struct nvkm_object *object, u32 mthd, void *data, u32 size)
 				return 0;
 			} else
 			if (args->v0.state != 0) {
-				nvkm_output_dp_train(&outpdp->base, 0, true);
+				nvkm_output_dp_train(&outpdp->base, 0);
 				return 0;
 			}
 		} else