[Intel-gfx] [PATCH] drm/i915: request ring to be pinned above GUC_WOPCM_TOP

[daniele.ceraolospurio at intel.com]

From: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>

GuC will validate the ring offset and fail if it is in the
[0, GUC_WOPCM_TOP) range.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa at intel.com>
Cc: Michał Winiarski <michal.winiarski at intel.com>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 69ccf4f..8f97b2e 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1807,8 +1807,11 @@ static int init_phys_status_page(struct intel_engine_cs *engine)
 
 int intel_ring_pin(struct intel_ring *ring)
 {
-	/* Ring wraparound at offset 0 sometimes hangs. No idea why. */
-	unsigned int flags = PIN_GLOBAL | PIN_OFFSET_BIAS | 4096;
+	/* Need a bias for 2 reasons:
+	 * 1: ring wraparound at offset 0 sometimes hangs. No idea why.
+	 * 2: GuC requires the ring to be placed above GUC_WOPCM_TOP
+	 */
+	unsigned int flags = PIN_GLOBAL | PIN_OFFSET_BIAS | GUC_WOPCM_TOP;
 	enum i915_map_type map;
 	struct i915_vma *vma = ring->vma;
 	void *addr;
-- 
1.9.1