From: dw kim <dongwon.kim@xxxxxxxxx>
Correct bit mapping of EUs in 'eu_disable' fuse register
for each subslice is (each word represents one subslice),
bit # 7 6 5 4 3 2 1 0
EU # 11 10 9 8 3 2 1 0
In BXT, each subslice has 6 EUs at most, which are EU0~EU2
and EU8~EU10 (EU11 and EU3 don't exist). Therefore, correct
eu_mask should be 0x77 to cover all EUs in each subslice that
can be possibly enabled.
v2: fixed some whitespaces and added "drm/i915:" to the title
Cc: Matthew D Roper <matthew.d.roper@xxxxxxxxx>
Signed-off-by: dw kim <dongwon.kim@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_dma.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 066a0ef..3f34dd3 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -633,13 +633,21 @@ static void gen9_sseu_info_init(struct drm_device *dev)
/*
* BXT has a single slice. BXT also has at most 6 EU per subslice,
- * and therefore only the lowest 6 bits of the 8-bit EU disable
- * fields are valid.
- */
+ * and bit mappings vs EU # in eu_disable fuse value in one subslice
+ * is like this;
+ *
+ * Bit # 7 6 5 4 3 2 1 0
+ * EU # 11 10 9 8 3 2 1 0
+ *
+ * Since only EUs with number "0, 1, 2, 8, 9, 10" are available in
+ * each subslice in BXT, bits in eu_mask should also be set according
+ * to this mapping, therefore, eu_mask = 0x77.
+ */
+
if (IS_BROXTON(dev)) {
s_max = 1;
eu_max = 6;
- eu_mask = 0x3f;
+ eu_mask = 0x77;
}
info = (struct intel_device_info *)&dev_priv->info;
--
1.9.1
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