nouveau: redo channel idle detection

Will hopefully work a bit better than previous code, which depended on
knowing the channel's most recent PUT value.  Some chips always return
0 on reading these regs, and currently userspace is the only other entity
which knows the value.

1 files changed, 29 insertions, 14 deletions

diff --git a/shared-core/nouveau_fifo.c b/shared-core/nouveau_fifo.c
index 8e93207e..d8fda277 100644
--- a/shared-core/nouveau_fifo.c
+++ b/shared-core/nouveau_fifo.c
@@ -390,6 +390,34 @@ nouveau_fifo_alloc(struct drm_device *dev, struct nouveau_channel **chan_ret,
         return 0;
 }
 
+static int
+nouveau_channel_idle(struct nouveau_channel *chan)
+{
+        struct drm_device *dev = chan->dev;
+        struct drm_nouveau_private *dev_priv = dev->dev_private;
+        struct nouveau_engine *engine = &dev_priv->Engine;
+        uint32_t caches;
+        int idle;
+
+        caches = NV_READ(NV03_PFIFO_CACHES);
+        NV_WRITE(NV03_PFIFO_CACHES, caches & ~1);
+
+        if (engine->fifo.channel_id(dev) != chan->id) {
+                struct nouveau_gpuobj *ramfc = chan->ramfc->gpuobj;
+
+                if (INSTANCE_RD(ramfc, 0) != INSTANCE_RD(ramfc, 1))
+                        idle = 0;
+                else
+                        idle = 1;
+        } else {
+                idle = (NV_READ(NV04_PFIFO_CACHE1_DMA_GET) ==
+                        NV_READ(NV04_PFIFO_CACHE1_DMA_PUT));
+        }
+
+        NV_WRITE(NV03_PFIFO_CACHES, caches);
+        return idle;
+}
+
 /* stops a fifo */
 void nouveau_fifo_free(struct nouveau_channel *chan)
 {
@@ -400,22 +428,9 @@ void nouveau_fifo_free(struct nouveau_channel *chan)
 
         DRM_INFO("%s: freeing fifo %d\n", __func__, chan->id);
 
-        /* Disable channel switching, if this channel isn't currenly
-         * active re-enable it if there's still pending commands.
-         * We really should do a manual context switch here, but I'm
-         * not sure I trust our ability to do this reliably yet..
-         */
-        NV_WRITE(NV03_PFIFO_CACHES, 0);
-        if (engine->fifo.channel_id(dev) != chan->id &&
-            NV_READ(chan->get) != NV_READ(chan->put)) {
-                NV_WRITE(NV03_PFIFO_CACHES, 1);
-        }
-
         /* Give the channel a chance to idle, wait 2s (hopefully) */
         t_start = engine->timer.read(dev);
-        while (NV_READ(chan->get) != NV_READ(chan->put) ||
-               NV_READ(NV03_PFIFO_CACHE1_GET) !=
-               NV_READ(NV03_PFIFO_CACHE1_PUT)) {
+        while (!nouveau_channel_idle(chan)) {
                 if (engine->timer.read(dev) - t_start > 2000000000ULL) {
                         DRM_ERROR("Failed to idle channel %d before destroy."
                                   "Prepare for strangeness..\n", chan->id);