drm/i915/bdw: The TLB invalidation mechanism has been removed from INSTPM

While wandering in the spec, I noticed that BDW removes those 2 bits
from INSTPM. I couldn't find any direct way to invalidate the TLB (ie
without the ring working already). Maybe someone will be more lucky.

At least, we now know we may be a problem.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index c50388a86bca..4eb3e062b4e3 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -981,8 +981,14 @@ void intel_ring_setup_status_page(struct intel_ring_buffer *ring)
         I915_WRITE(mmio, (u32)ring->status_page.gfx_addr);
         POSTING_READ(mmio);
 
-        /* Flush the TLB for this page */
-        if (INTEL_INFO(dev)->gen >= 6) {
+        /*
+         * Flush the TLB for this page
+         *
+         * FIXME: These two bits have disappeared on gen8, so a question
+         * arises: do we still need this and if so how should we go about
+         * invalidating the TLB?
+         */
+        if (INTEL_INFO(dev)->gen >= 6 && INTEL_INFO(dev)->gen < 8) {
                 u32 reg = RING_INSTPM(ring->mmio_base);
 
                 /* ring should be idle before issuing a sync flush*/