drm/nv50: avoid unloading pgraph context when ctxprog is running

- We need to disable pgraph fifo access before checking the current channel,
  otherwise we could still hit a running ctxprog.
- The writes to 0x400500 are already handled by pgraph->fifo_access and are
  therefore redundant, moreover pgraph fifo access should not be reenabled
  before current context is set as invalid. So remove them altogether.

Signed-off-by: Maarten Maathuis <madman2003@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

2 files changed, 10 insertions, 7 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_channel.c b/drivers/gpu/drm/nouveau/nouveau_channel.c
index 343d718a9667..2281f99da7fc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_channel.c
+++ b/drivers/gpu/drm/nouveau/nouveau_channel.c
@@ -278,12 +278,11 @@ nouveau_channel_free(struct nouveau_channel *chan)
         /* Ensure the channel is no longer active on the GPU */
         pfifo->reassign(dev, false);
 
-        if (pgraph->channel(dev) == chan) {
-                pgraph->fifo_access(dev, false);
+        pgraph->fifo_access(dev, false);
+        if (pgraph->channel(dev) == chan)
                 pgraph->unload_context(dev);
-                pgraph->fifo_access(dev, true);
-        }
         pgraph->destroy_context(chan);
+        pgraph->fifo_access(dev, true);
 
         if (pfifo->channel_id(dev) == chan->id) {
                 pfifo->disable(dev);
diff --git a/drivers/gpu/drm/nouveau/nv50_graph.c b/drivers/gpu/drm/nouveau/nv50_graph.c
index 20319e59d368..6d504801b514 100644
--- a/drivers/gpu/drm/nouveau/nv50_graph.c
+++ b/drivers/gpu/drm/nouveau/nv50_graph.c
@@ -165,6 +165,12 @@ nv50_graph_channel(struct drm_device *dev)
         uint32_t inst;
         int i;
 
+        /* Be sure we're not in the middle of a context switch or bad things
+         * will happen, such as unloading the wrong pgraph context.
+         */
+        if (!nv_wait(0x400300, 0x00000001, 0x00000000))
+                NV_ERROR(dev, "Ctxprog is still running\n");
+
         inst = nv_rd32(dev, NV50_PGRAPH_CTXCTL_CUR);
         if (!(inst & NV50_PGRAPH_CTXCTL_CUR_LOADED))
                 return NULL;
@@ -275,7 +281,7 @@ nv50_graph_load_context(struct nouveau_channel *chan)
 int
 nv50_graph_unload_context(struct drm_device *dev)
 {
-        uint32_t inst, fifo = nv_rd32(dev, 0x400500);
+        uint32_t inst;
 
         inst  = nv_rd32(dev, NV50_PGRAPH_CTXCTL_CUR);
         if (!(inst & NV50_PGRAPH_CTXCTL_CUR_LOADED))
@@ -283,12 +289,10 @@ nv50_graph_unload_context(struct drm_device *dev)
         inst &= NV50_PGRAPH_CTXCTL_CUR_INSTANCE;
 
         nouveau_wait_for_idle(dev);
-        nv_wr32(dev, 0x400500, fifo & ~1);
         nv_wr32(dev, 0x400784, inst);
         nv_wr32(dev, 0x400824, nv_rd32(dev, 0x400824) | 0x20);
         nv_wr32(dev, 0x400304, nv_rd32(dev, 0x400304) | 0x01);
         nouveau_wait_for_idle(dev);
-        nv_wr32(dev, 0x400500, fifo);
 
         nv_wr32(dev, NV50_PGRAPH_CTXCTL_CUR, inst);
         return 0;