[RFC] drm/xe/guc: Don't support GuC older GuC 70.x releases

[Daniele Ceraolo Spurio]

Supporting older GuC versions comes with baggage, both on the coding
side (due to interfaces only being available from a certain version
onwards) and on the testing side (due to having to make sure the driver
works as expected with older GuCs).
Since all of our Xe platform are still under force probe, we haven't
committed to support any specific GuC version and we therefore don't
need to support the older once, which means that we can force a bottom
limit to what GuC we accept. This allows us to remove any conditional
statements based on older GuC versions and also to approach newer
additions knowing that we'll never attempt to load something older
than our minimum requirement.

RFC: this patch sets the minimum to the current GuC version (70.19),
but that can be moved one way or the other. The main aim here is
agreeing to stop supporting very old GuC releases on the newer driver.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: John Harrison <John.C.Harrison at Intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: Matt Roper <matthew.d.roper at intel.com>
Cc: Matthew Brost <matthew.brost at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/xe/xe_guc.c   | 14 ++------------
 drivers/gpu/drm/xe/xe_uc_fw.c | 36 ++++++++++++++---------------------
 2 files changed, 16 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
index 868208a39829..5e6b27aac495 100644
--- a/drivers/gpu/drm/xe/xe_guc.c
+++ b/drivers/gpu/drm/xe/xe_guc.c
@@ -132,15 +132,10 @@ static u32 guc_ctl_ads_flags(struct xe_guc *guc)
 	return flags;
 }
 
-#define GUC_VER(maj, min, pat)	(((maj) << 16) | ((min) << 8) | (pat))
-
 static u32 guc_ctl_wa_flags(struct xe_guc *guc)
 {
 	struct xe_device *xe = guc_to_xe(guc);
 	struct xe_gt *gt = guc_to_gt(guc);
-	struct xe_uc_fw *uc_fw = &guc->fw;
-	struct xe_uc_fw_version *version = &uc_fw->versions.found[XE_UC_FW_VER_RELEASE];
-
 	u32 flags = 0;
 
 	if (XE_WA(gt, 22012773006))
@@ -170,13 +165,8 @@ static u32 guc_ctl_wa_flags(struct xe_guc *guc)
 	if (XE_WA(gt, 1509372804))
 		flags |= GUC_WA_RENDER_RST_RC6_EXIT;
 
-	if (XE_WA(gt, 14018913170)) {
-		if (GUC_VER(version->major, version->minor, version->patch) >= GUC_VER(70, 7, 0))
-			flags |= GUC_WA_ENABLE_TSC_CHECK_ON_RC6;
-		else
-			drm_dbg(&xe->drm, "Skip WA 14018913170: GUC version expected >= 70.7.0, found %u.%u.%u\n",
-				version->major, version->minor, version->patch);
-	}
+	if (XE_WA(gt, 14018913170))
+		flags |= GUC_WA_ENABLE_TSC_CHECK_ON_RC6;
 
 	return flags;
 }
diff --git a/drivers/gpu/drm/xe/xe_uc_fw.c b/drivers/gpu/drm/xe/xe_uc_fw.c
index 4714f2c8d2ba..e5bf59616f3d 100644
--- a/drivers/gpu/drm/xe/xe_uc_fw.c
+++ b/drivers/gpu/drm/xe/xe_uc_fw.c
@@ -296,36 +296,28 @@ static void uc_fw_fini(struct drm_device *drm, void *arg)
 	xe_uc_fw_change_status(uc_fw, XE_UC_FIRMWARE_SELECTED);
 }
 
-static void guc_read_css_info(struct xe_uc_fw *uc_fw, struct uc_css_header *css)
+static int guc_read_css_info(struct xe_uc_fw *uc_fw, struct uc_css_header *css)
 {
 	struct xe_gt *gt = uc_fw_to_gt(uc_fw);
 	struct xe_uc_fw_version *release = &uc_fw->versions.found[XE_UC_FW_VER_RELEASE];
 	struct xe_uc_fw_version *compatibility = &uc_fw->versions.found[XE_UC_FW_VER_COMPATIBILITY];
 
 	xe_gt_assert(gt, uc_fw->type == XE_UC_FW_TYPE_GUC);
-	xe_gt_assert(gt, release->major >= 70);
-
-	if (release->major > 70 || release->minor >= 6) {
-		/* v70.6.0 adds CSS header support */
-		compatibility->major = FIELD_GET(CSS_SW_VERSION_UC_MAJOR,
-						 css->submission_version);
-		compatibility->minor = FIELD_GET(CSS_SW_VERSION_UC_MINOR,
-						 css->submission_version);
-		compatibility->patch = FIELD_GET(CSS_SW_VERSION_UC_PATCH,
-						 css->submission_version);
-	} else if (release->minor >= 3) {
-		/* v70.3.0 introduced v1.1.0 */
-		compatibility->major = 1;
-		compatibility->minor = 1;
-		compatibility->patch = 0;
-	} else {
-		/* v70.0.0 introduced v1.0.0 */
-		compatibility->major = 1;
-		compatibility->minor = 0;
-		compatibility->patch = 0;
+
+	/* We don't support GuC releases older than 70.19 */
+	if (release->major < 70 || (release->major == 70 && release->minor < 19)) {
+		xe_gt_err(gt, "Unsupported GuC v%u.%u! v70.19 or newer is required\n",
+			  release->major, release->minor);
+		return -EINVAL;
 	}
 
+	compatibility->major = FIELD_GET(CSS_SW_VERSION_UC_MAJOR, css->submission_version);
+	compatibility->minor = FIELD_GET(CSS_SW_VERSION_UC_MINOR, css->submission_version);
+	compatibility->patch = FIELD_GET(CSS_SW_VERSION_UC_PATCH, css->submission_version);
+
 	uc_fw->private_data_size = css->private_data_size;
+
+	return 0;
 }
 
 int xe_uc_fw_check_version_requirements(struct xe_uc_fw *uc_fw)
@@ -424,7 +416,7 @@ static int parse_css_header(struct xe_uc_fw *uc_fw, const void *fw_data, size_t
 	release->patch = FIELD_GET(CSS_SW_VERSION_UC_PATCH, css->sw_version);
 
 	if (uc_fw->type == XE_UC_FW_TYPE_GUC)
-		guc_read_css_info(uc_fw, css);
+		return guc_read_css_info(uc_fw, css);
 
 	return 0;
 }
-- 
2.43.0