drm/i915/xelpg: Add multicast steering

MTL's graphics IP (Xe_LPG) once again changes the multicast register
types and steering details.  Key changes from past platforms:
 * The number of instances of some MCR types (NODE, OAAL2, and GAM) vary
   according to the MTL subplatform and cannot be read from fuse
   registers.  However steering to instance #0 will always provided a
   non-terminated value, so we can lump these all into a single
   "instance0" table.
 * The MCR steering register (and its bitfields) has changed.

Unlike past platforms, we will be explicitly steering all types of MCR
accesses, including those for "SLICE" and "DSS" ranges; we no longer
rely on implicit steering.  On previous platforms, various
hardware/firmware agents that needed to access registers typically had
their own steering control registers, allowing them to perform multicast
steering without clobbering the CPU/kernel steering.  Starting with MTL,
more of these agents now share a single steering register (0xFD4) and it
is no longer safe for us to assume that the value will remain unchanged
from how we initialized it during startup.  There is also a slight
chance of race conditions between the driver and a hardware/firmware
agent, so the hardware provides a semaphore register that can be used to
coordinate access to the steering register.  Support for the semaphore
register will be introduced in a future patch.

v2:
 - Use Xe_LPG terminology instead of "MTL 3D" since it's the IP version
   we're matching on now rather than the platform.
 - Don't combine l3bank and mslice masks into a union.  It's not related
   to the other changes here and we might still need both of them on
   some future platform.
 - Separate debug dumping of steering settings to a separate helper
   function.  (Tvrtko)
 - Update debug dumping to include DSS ranges (and future-proof it so
   that any new ranges added on future platforms will also be dumped).
 - Restore MULTICAST bit at the end of rw_with_mcr_steering_fw() if we
   cleared it.  Also force the MULTICAST bit to true at the beginning of
   multicast writes just to be safe.  (Bala)

Bspec: 67788, 67112
Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Cc: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221014230239.1023689-14-matthew.d.roper@intel.com

1 files changed, 28 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index dadb60e6a58f..711a31935857 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -1128,18 +1128,23 @@ static void __set_mcr_steering(struct i915_wa_list *wal,
 	wa_write_clr_set(wal, steering_reg, mcr_mask, mcr);
 }
 
-static void __add_mcr_wa(struct intel_gt *gt, struct i915_wa_list *wal,
-			 unsigned int slice, unsigned int subslice)
+static void debug_dump_steering(struct intel_gt *gt)
 {
 	struct drm_printer p = drm_debug_printer("MCR Steering:");
 
+	if (drm_debug_enabled(DRM_UT_DRIVER))
+		intel_gt_mcr_report_steering(&p, gt, false);
+}
+
+static void __add_mcr_wa(struct intel_gt *gt, struct i915_wa_list *wal,
+			 unsigned int slice, unsigned int subslice)
+{
 	__set_mcr_steering(wal, GEN8_MCR_SELECTOR, slice, subslice);
 
 	gt->default_steering.groupid = slice;
 	gt->default_steering.instanceid = subslice;
 
-	if (drm_debug_enabled(DRM_UT_DRIVER))
-		intel_gt_mcr_report_steering(&p, gt, false);
+	debug_dump_steering(gt);
 }
 
 static void
@@ -1582,11 +1587,29 @@ pvc_gt_workarounds_init(struct intel_gt *gt, struct i915_wa_list *wal)
 }
 
 static void
+xelpg_gt_workarounds_init(struct intel_gt *gt, struct i915_wa_list *wal)
+{
+	/* FIXME: Actual workarounds will be added in future patch(es) */
+
+	/*
+	 * Unlike older platforms, we no longer setup implicit steering here;
+	 * all MCR accesses are explicitly steered.
+	 */
+	debug_dump_steering(gt);
+}
+
+static void
 gt_init_workarounds(struct intel_gt *gt, struct i915_wa_list *wal)
 {
 	struct drm_i915_private *i915 = gt->i915;
 
-	if (IS_PONTEVECCHIO(i915))
+	/* FIXME: Media GT handling will be added in an upcoming patch */
+	if (gt->type == GT_MEDIA)
+		return;
+
+	if (GRAPHICS_VER_FULL(i915) >= IP_VER(12, 70))
+		xelpg_gt_workarounds_init(gt, wal);
+	else if (IS_PONTEVECCHIO(i915))
 		pvc_gt_workarounds_init(gt, wal);
 	else if (IS_DG2(i915))
 		dg2_gt_workarounds_init(gt, wal);