From: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

Revert to the original explicit approach and document the reasoning
behind it.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Cc: Matt Roper <matthew.d.ro...@intel.com>
Cc: Balasubramani Vivekanandan <balasubramani.vivekanan...@intel.com>
Cc: Andrzej Hajda <andrzej.ha...@intel.com>
---
 drivers/gpu/drm/i915/gt/intel_gt.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c 
b/drivers/gpu/drm/i915/gt/intel_gt.c
index 7eeee5a7cb33..854841a731cb 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt.c
@@ -1070,7 +1070,18 @@ static void mmio_invalidate_full(struct intel_gt *gt)
        unsigned int num = 0;
        unsigned long flags;
 
-       if (GRAPHICS_VER_FULL(i915) >= IP_VER(12, 50)) {
+       /*
+        * New platforms should not be added with catch-all-newer (>=)
+        * condition so that any later platform added triggers the below warning
+        * and in turn mandates a human cross-check of whether the invalidation
+        * flows have compatible semantics.
+        *
+        * For instance with the 11.00 -> 12.00 transition three out of five
+        * respective engine registers were moved to masked type. Then after the
+        * 12.00 -> 12.50 transition multi cast handling is required too.
+        */
+
+       if (GRAPHICS_VER_FULL(i915) == IP_VER(12, 50)) {
                regs = NULL;
                num = ARRAY_SIZE(xehp_regs);
        } else if (GRAPHICS_VER(i915) == 12) {
-- 
2.34.1

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