[PATCH 4.19 34/44] drm/nouveau/kms/nv50-: also flush fb writes when rewinding push buffer

[Greg Kroah-Hartman]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Skeggs <bske...@redhat.com>

commit 970a5ee41c72df46e3b0f307528c7d8ef7734a2e upstream.

Should hopefully fix a regression some people have been seeing since EVO
push buffers were moved to VRAM by default on Pascal GPUs.

Fixes: d00ddd9da ("drm/nouveau/kms/nv50-: allocate push buffers in vidmem on 
pascal")
Signed-off-by: Ben Skeggs <bske...@redhat.com>
Cc: <sta...@vger.kernel.org> # 4.19+
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/gpu/drm/nouveau/dispnv50/disp.c |   29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -197,6 +197,22 @@ nv50_dmac_create(struct nvif_device *dev
 /******************************************************************************
  * EVO channel helpers
  *****************************************************************************/
+static void
+evo_flush(struct nv50_dmac *dmac)
+{
+       /* Push buffer fetches are not coherent with BAR1, we need to ensure
+        * writes have been flushed right through to VRAM before writing PUT.
+        */
+       if (dmac->push.type & NVIF_MEM_VRAM) {
+               struct nvif_device *device = dmac->base.device;
+               nvif_wr32(&device->object, 0x070000, 0x00000001);
+               nvif_msec(device, 2000,
+                       if (!(nvif_rd32(&device->object, 0x070000) & 
0x00000002))
+                               break;
+               );
+       }
+}
+
 u32 *
 evo_wait(struct nv50_dmac *evoc, int nr)
 {
@@ -207,6 +223,7 @@ evo_wait(struct nv50_dmac *evoc, int nr)
        mutex_lock(&dmac->lock);
        if (put + nr >= (PAGE_SIZE / 4) - 8) {
                dmac->ptr[put] = 0x20000000;
+               evo_flush(dmac);
 
                nvif_wr32(&dmac->base.user, 0x0000, 0x00000000);
                if (nvif_msec(device, 2000,
@@ -229,17 +246,7 @@ evo_kick(u32 *push, struct nv50_dmac *ev
 {
        struct nv50_dmac *dmac = evoc;
 
-       /* Push buffer fetches are not coherent with BAR1, we need to ensure
-        * writes have been flushed right through to VRAM before writing PUT.
-        */
-       if (dmac->push.type & NVIF_MEM_VRAM) {
-               struct nvif_device *device = dmac->base.device;
-               nvif_wr32(&device->object, 0x070000, 0x00000001);
-               nvif_msec(device, 2000,
-                       if (!(nvif_rd32(&device->object, 0x070000) & 
0x00000002))
-                               break;
-               );
-       }
+       evo_flush(dmac);
 
        nvif_wr32(&dmac->base.user, 0x0000, (push - dmac->ptr) << 2);
        mutex_unlock(&dmac->lock);