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

Greg Kroah-Hartman
2018-12-18T16:42:41Z

From: Ben Skeggs <bskeggs@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 <bskeggs@redhat.com>
Cc: <stable@vger.kernel.org> # 4.19+
Signed-off-by: Greg Kroah-Hartman <gregkh@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);