From: Damien Lespiau <damien.lesp...@intel.com>

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.lesp...@intel.com>
Reviewed-by: Ben Widawsky <b...@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vet...@ffwll.ch>
[BDW 3.14 backport]
Cc: sta...@vger.kernel.org
Signed-off-by: Ben Widawsky <b...@bwidawsk.net>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c 
b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 2ac8f94..c1ee5ef 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -977,8 +977,14 @@ 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);
                I915_WRITE(reg,
                           _MASKED_BIT_ENABLE(INSTPM_TLB_INVALIDATE |
-- 
1.9.1

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