drm/nouveau: prevent all channel creation if accel not available

Previously, if there was no firmware available, the DRM would just
disable channel creation from userspace, but still use a single
channel for its own purposes.

With a bit of care it should actually be possible to do this, due
to the DRM's very limited use of the engine.  It currently doesn't
work correctly however, resulting in corrupted fbcon and hangs on
a number of cards.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

3 files changed, 64 insertions, 48 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index e9f01906c52..2f5d4702110 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -461,11 +461,8 @@ nouveau_bo_move_m2mf(struct ttm_buffer_object *bo, int evict, int no_wait,
         int ret;
 
         chan = nvbo->channel;
-        if (!chan || nvbo->tile_flags || nvbo->no_vm) {
+        if (!chan || nvbo->tile_flags || nvbo->no_vm)
                 chan = dev_priv->channel;
-                if (!chan)
-                        return -EINVAL;
-        }
 
         src_offset = old_mem->mm_node->start << PAGE_SHIFT;
         dst_offset = new_mem->mm_node->start << PAGE_SHIFT;
@@ -631,7 +628,8 @@ nouveau_bo_move(struct ttm_buffer_object *bo, bool evict, bool intr,
                         return ret;
         }
 
-        if (dev_priv->init_state != NOUVEAU_CARD_INIT_DONE)
+        if (dev_priv->init_state != NOUVEAU_CARD_INIT_DONE ||
+            !dev_priv->channel)
                 return ttm_bo_move_memcpy(bo, evict, no_wait, new_mem);
 
         if (old_mem->mem_type == TTM_PL_SYSTEM && !bo->ttm) {
diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
index 489d4926811..84af25c238b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
@@ -58,7 +58,7 @@ nouveau_fbcon_sync(struct fb_info *info)
         struct nouveau_channel *chan = dev_priv->channel;
         int ret, i;
 
-        if (!chan->accel_done ||
+        if (!chan || !chan->accel_done ||
             info->state != FBINFO_STATE_RUNNING ||
             info->flags & FBINFO_HWACCEL_DISABLED)
                 return 0;
@@ -318,14 +318,16 @@ nouveau_fbcon_create(struct drm_device *dev, uint32_t fb_width,
         par->nouveau_fb = nouveau_fb;
         par->dev = dev;
 
-        switch (dev_priv->card_type) {
-        case NV_50:
-                nv50_fbcon_accel_init(info);
-                break;
-        default:
-                nv04_fbcon_accel_init(info);
-                break;
-        };
+        if (dev_priv->channel) {
+                switch (dev_priv->card_type) {
+                case NV_50:
+                        nv50_fbcon_accel_init(info);
+                        break;
+                default:
+                        nv04_fbcon_accel_init(info);
+                        break;
+                };
+        }
 
         nouveau_fbcon_zfill(dev);
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_state.c b/drivers/gpu/drm/nouveau/nouveau_state.c
index 9fc582432da..e76ec2d207a 100644
--- a/drivers/gpu/drm/nouveau/nouveau_state.c
+++ b/drivers/gpu/drm/nouveau/nouveau_state.c
@@ -299,12 +299,57 @@ nouveau_vga_set_decode(void *priv, bool state)
                 return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 }
 
+static int
+nouveau_card_init_channel(struct drm_device *dev)
+{
+        struct drm_nouveau_private *dev_priv = dev->dev_private;
+        struct nouveau_gpuobj *gpuobj;
+        int ret;
+
+        ret = nouveau_channel_alloc(dev, &dev_priv->channel,
+                                    (struct drm_file *)-2,
+                                    NvDmaFB, NvDmaTT);
+        if (ret)
+                return ret;
+
+        gpuobj = NULL;
+        ret = nouveau_gpuobj_dma_new(dev_priv->channel, NV_CLASS_DMA_IN_MEMORY,
+                                     0, nouveau_mem_fb_amount(dev),
+                                     NV_DMA_ACCESS_RW, NV_DMA_TARGET_VIDMEM,
+                                     &gpuobj);
+        if (ret)
+                goto out_err;
+
+        ret = nouveau_gpuobj_ref_add(dev, dev_priv->channel, NvDmaVRAM,
+                                     gpuobj, NULL);
+        if (ret)
+                goto out_err;
+
+        gpuobj = NULL;
+        ret = nouveau_gpuobj_gart_dma_new(dev_priv->channel, 0,
+                                          dev_priv->gart_info.aper_size,
+                                          NV_DMA_ACCESS_RW, &gpuobj, NULL);
+        if (ret)
+                goto out_err;
+
+        ret = nouveau_gpuobj_ref_add(dev, dev_priv->channel, NvDmaGART,
+                                     gpuobj, NULL);
+        if (ret)
+                goto out_err;
+
+        return 0;
+out_err:
+        nouveau_gpuobj_del(dev, &gpuobj);
+        nouveau_channel_free(dev_priv->channel);
+        dev_priv->channel = NULL;
+        return ret;
+}
+
 int
 nouveau_card_init(struct drm_device *dev)
 {
         struct drm_nouveau_private *dev_priv = dev->dev_private;
         struct nouveau_engine *engine;
-        struct nouveau_gpuobj *gpuobj;
         int ret;
 
         NV_DEBUG(dev, "prev state = %d\n", dev_priv->init_state);
@@ -387,39 +432,10 @@ nouveau_card_init(struct drm_device *dev)
 
         /* what about PVIDEO/PCRTC/PRAMDAC etc? */
 
-        ret = nouveau_channel_alloc(dev, &dev_priv->channel,
-                                    (struct drm_file *)-2,
-                                    NvDmaFB, NvDmaTT);
-        if (ret)
-                goto out_irq;
-
-        gpuobj = NULL;
-        ret = nouveau_gpuobj_dma_new(dev_priv->channel, NV_CLASS_DMA_IN_MEMORY,
-                                     0, nouveau_mem_fb_amount(dev),
-                                     NV_DMA_ACCESS_RW, NV_DMA_TARGET_VIDMEM,
-                                     &gpuobj);
-        if (ret)
-                goto out_irq;
-
-        ret = nouveau_gpuobj_ref_add(dev, dev_priv->channel, NvDmaVRAM,
-                                     gpuobj, NULL);
-        if (ret) {
-                nouveau_gpuobj_del(dev, &gpuobj);
-                goto out_irq;
-        }
-
-        gpuobj = NULL;
-        ret = nouveau_gpuobj_gart_dma_new(dev_priv->channel, 0,
-                                          dev_priv->gart_info.aper_size,
-                                          NV_DMA_ACCESS_RW, &gpuobj, NULL);
-        if (ret)
-                goto out_irq;
-
-        ret = nouveau_gpuobj_ref_add(dev, dev_priv->channel, NvDmaGART,
-                                     gpuobj, NULL);
-        if (ret) {
-                nouveau_gpuobj_del(dev, &gpuobj);
-                goto out_irq;
+        if (!engine->graph.accel_blocked) {
+                ret = nouveau_card_init_channel(dev);
+                if (ret)
+                        goto out_irq;
         }
 
         if (drm_core_check_feature(dev, DRIVER_MODESET)) {