drm/i915/perf: Wa_14017512683: Disable OAM if media C6 is enabled in BIOS

OAM does not work with media C6 enabled on some steppings of MTL.
Disable OAM if we detect that media C6 was enabled in bios.

v2: (Ashutosh)
- Remove drm_notice from the driver load path
- Log a drm_err when opening an OAM stream on affected steppings

v3:
- Initialize the engine group even if mc6 is enabled (Ashutosh)
- Checkpatch fix
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323225901.3743681-12-umesh.nerlige.ramappa@intel.com

drivers/gpu/drm/i915/i915_perf.c

@@ -209,6 +209,7 @@
 #include "gt/intel_gt_regs.h"
 #include "gt/intel_lrc.h"
 #include "gt/intel_lrc_reg.h"
+#include "gt/intel_rc6.h"
 #include "gt/intel_ring.h"
 #include "gt/uc/intel_guc_slpc.h"
 
@@ -4223,6 +4224,19 @@ static int read_properties_unlocked(struct i915_perf *perf,
 		return -EINVAL;
 	}
 
+	/*
+	 * Wa_14017512683: mtl[a0..c0): Use of OAM must be preceded with Media
+	 * C6 disable in BIOS. Fail if Media C6 is enabled on steppings where OAM
+	 * does not work as expected.
+	 */
+	if (IS_MTL_MEDIA_STEP(props->engine->i915, STEP_A0, STEP_C0) &&
+	    props->engine->oa_group->type == TYPE_OAM &&
+	    intel_check_bios_c6_setup(&props->engine->gt->rc6)) {
+		drm_dbg(&perf->i915->drm,
+			"OAM requires media C6 to be disabled in BIOS\n");
+		return -EINVAL;
+	}
+
 	i = array_index_nospec(props->oa_format, I915_OA_FORMAT_MAX);
 	f = &perf->oa_formats[i];
 	if (!engine_supports_oa_format(props->engine, f->type)) {
@@ -5316,6 +5330,23 @@ int i915_perf_ioctl_version(struct drm_i915_private *i915)
 	 *
 	 * 7: Add support for video decode and enhancement classes.
 	 */
+
+	/*
+	 * Wa_14017512683: mtl[a0..c0): Use of OAM must be preceded with Media
+	 * C6 disable in BIOS. If Media C6 is enabled in BIOS, return version 6
+	 * to indicate that OA media is not supported.
+	 */
+	if (IS_MTL_MEDIA_STEP(i915, STEP_A0, STEP_C0)) {
+		struct intel_gt *gt;
+		int i;
+
+		for_each_gt(gt, i915, i) {
+			if (gt->type == GT_MEDIA &&
+			    intel_check_bios_c6_setup(&gt->rc6))
+				return 6;
+		}
+	}
+
 	return 7;
 }