[Intel-gfx] [PATCH] drm/i915/icl: Adjust BSD2 semantics to mean any second VCS instance

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Currently our driver assumes BSD2 means hardware engine instance number
two. This does not work for Icelake parts with two VCS engines, but which
are hardware instances 0 and 2, and not 0 and 1 as with previous parts.

This makes the second engine not discoverable via HAS_BSD2 get param, nor
it can be targetted by execbuf.

While we are working on the next generation execbuf put in a hack which
allows discovery and access to this second VCS engine using legacy ABI.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Jon Bloomfield <jon.bloomfield at intel.com>
Cc: Tony Ye <tony.ye at intel.com>
---
Compile tested only.

Also, one could argue if this is just a temporary hack or could actually
make sense to have this permanently in. It feels like the ABI semantics of
BSD2 are blurry, or at least could be re-blurred for Gen11.
---
 drivers/gpu/drm/i915/i915_drv.c            |  8 +++++++-
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 10 +++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index b7dbeba72dec..a185366d9beb 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -331,7 +331,13 @@ static int i915_getparam_ioctl(struct drm_device *dev, void *data,
 		value = !!dev_priv->engine[VECS];
 		break;
 	case I915_PARAM_HAS_BSD2:
-		value = !!dev_priv->engine[VCS2];
+		/*
+		 * FIXME: Temporary hack for Icelake.
+		 *
+		 * Make semantics of HAS_BSD2 "has second", or "has two" VDBOXes
+		 * instead of "has VDBOX 2nd hardware instance".
+		 */
+		value = dev_priv->engine[VCS2] || dev_priv->engine[VCS3];
 		break;
 	case I915_PARAM_HAS_LLC:
 		value = HAS_LLC(dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index c74f5df3fb5a..80b32460567d 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -2052,7 +2052,9 @@ eb_select_engine(struct drm_i915_private *dev_priv,
 		return NULL;
 	}
 
-	if (user_ring_id == I915_EXEC_BSD && HAS_BSD2(dev_priv)) {
+	if (user_ring_id == I915_EXEC_BSD &&
+	    (INTEL_INFO(dev_priv)->ring_mask &
+	     (ENGINE_MASK(_VCS(1)) | ENGINE_MASK(_VCS(2))))) {
 		unsigned int bsd_idx = args->flags & I915_EXEC_BSD_MASK;
 
 		if (bsd_idx == I915_EXEC_BSD_DEFAULT) {
@@ -2068,6 +2070,12 @@ eb_select_engine(struct drm_i915_private *dev_priv,
 		}
 
 		engine = dev_priv->engine[_VCS(bsd_idx)];
+
+		/*
+		 * FIXME Temporarily map VCS2 to VCS1 on Icelake.
+		 */
+		if (!engine && bsd_idx)
+			engine = dev_priv->engine[_VCS(2)];
 	} else {
 		engine = dev_priv->engine[user_ring_map[user_ring_id]];
 	}
-- 
2.14.1