drm/i915/dg2: Incorporate Wa_16014892111 into DRAW_WATERMARK tuning

Although register tuning settings are generally implemented via the
workaround infrastructure, it turns out that the DRAW_WATERMARK register
is not properly saved/restored by hardware around power events (i.e.,
RC6 entry) so updates to the value cannot be applied in the usual
manner.  New workaround Wa_16014892111 informs us that any tuning
updates to this register must instead be applied via an INDIRECT_CTX
batch buffer.  This will ensure that the necessary value is re-applied
when a context begins running, even if an RC6 entry had wiped the
register back to hardware defaults since the last context ran.

Fixes: 6dc8572 ("drm/i915/dg2: Add additional tuning settings")
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6642
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/20220823202449.83727-1-matthew.d.roper@intel.com

drivers/gpu/drm/i915/gt/intel_lrc.c

@@ -1242,6 +1242,23 @@ dg2_emit_rcs_hang_wabb(const struct intel_context *ce, u32 *cs)
 	return cs;
 }
 
+/*
+ * The bspec's tuning guide asks us to program a vertical watermark value of
+ * 0x3FF.  However this register is not saved/restored properly by the
+ * hardware, so we're required to apply the desired value via INDIRECT_CTX
+ * batch buffer to ensure the value takes effect properly.  All other bits
+ * in this register should remain at 0 (the hardware default).
+ */
+static u32 *
+dg2_emit_draw_watermark_setting(u32 *cs)
+{
+	*cs++ = MI_LOAD_REGISTER_IMM(1);
+	*cs++ = i915_mmio_reg_offset(DRAW_WATERMARK);
+	*cs++ = REG_FIELD_PREP(VERT_WM_VAL, 0x3FF);
+
+	return cs;
+}
+
 static u32 *
 gen12_emit_indirect_ctx_rcs(const struct intel_context *ce, u32 *cs)
 {
@@ -1263,6 +1280,10 @@ gen12_emit_indirect_ctx_rcs(const struct intel_context *ce, u32 *cs)
 	if (!HAS_FLAT_CCS(ce->engine->i915))
 		cs = gen12_emit_aux_table_inv(cs, GEN12_GFX_CCS_AUX_NV);
 
+	/* Wa_16014892111 */
+	if (IS_DG2(ce->engine->i915))
+		cs = dg2_emit_draw_watermark_setting(cs);
+
 	return cs;
 }
 

drivers/gpu/drm/i915/gt/intel_workarounds.c

@@ -2685,8 +2685,6 @@ add_render_compute_tuning_settings(struct drm_i915_private *i915,
 	if (IS_DG2(i915)) {
 		wa_write_or(wal, XEHP_L3SCQREG7, BLEND_FILL_CACHING_OPT_DIS);
 		wa_write_clr_set(wal, RT_CTRL, STACKID_CTRL, STACKID_CTRL_512);
-		wa_write_clr_set(wal, DRAW_WATERMARK, VERT_WM_VAL,
-				 REG_FIELD_PREP(VERT_WM_VAL, 0x3FF));
 
 		/*
 		 * This is also listed as Wa_22012654132 for certain DG2