[Intel-gfx] [PATCH 2/2] drm/i915: Don't try to set INSTPM for the _ABSOLUTE constant buffer address

[Damien Lespiau]

Gen9 bit to control whether the 3DSTATE_CONSTANT_* address should be an
offset against the Dynamic State Base Address Vs an absolute address has
moved to a different register.

As no-one complained yet and I don't see any use of the
I915_EXEC_CONSTANTS_ABSOLUTE flag in either the DDX, mesa, libdrm or
libva, I'm taking the opportunity to deprecate the flag on gen9 (it
never worked in the first place).

Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 13 ++++++++++++-
 include/uapi/drm/i915_drm.h      |  2 +-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 896641a..836356a 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -647,6 +647,16 @@ int intel_execlists_submission(struct drm_device *dev, struct drm_file *file,
 	case I915_EXEC_CONSTANTS_REL_GENERAL:
 	case I915_EXEC_CONSTANTS_ABSOLUTE:
 	case I915_EXEC_CONSTANTS_REL_SURFACE:
+		if (instp_mode != 0 && INTEL_INFO(dev)->gen >= 9) {
+			/*
+			 * While it's possible to implement _ABSOLUTE, noone
+			 * complained when it was broken, so let's simplify the
+			 * driver by not supporting it until further notice.
+			 */
+			DRM_DEBUG("no rel constants on gen9+\n");
+			return -EINVAL;
+		}
+
 		if (instp_mode != 0 && ring != &dev_priv->ring[RCS]) {
 			DRM_DEBUG("non-0 rel constants mode on non-RCS\n");
 			return -EINVAL;
@@ -691,7 +701,8 @@ int intel_execlists_submission(struct drm_device *dev, struct drm_file *file,
 	if (ret)
 		return ret;
 
-	if (instp_mode != dev_priv->relative_constants_mode &&
+	/* We deprecated the I915_EXEC_CONSTANTS on gen9+, for lack of user */
+	if (instp_mode != dev_priv->relative_constants_mode && IS_GEN8(dev) &&
 	    ring == &dev_priv->ring[RCS]) {
 		ret = intel_logical_ring_begin(ringbuf, ctx, 4);
 		if (ret)
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 6eed16b..d7c17b7 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -715,7 +715,7 @@ struct drm_i915_gem_execbuffer2 {
  */
 #define I915_EXEC_CONSTANTS_MASK 	(3<<6)
 #define I915_EXEC_CONSTANTS_REL_GENERAL (0<<6) /* default */
-#define I915_EXEC_CONSTANTS_ABSOLUTE 	(1<<6)
+#define I915_EXEC_CONSTANTS_ABSOLUTE 	(1<<6) /* gen 4/5/6/7/8 only */
 #define I915_EXEC_CONSTANTS_REL_SURFACE (2<<6) /* gen4/5 only */
 	__u64 flags;
 	__u64 rsvd1; /* now used for context info */
-- 
1.8.3.1