From: Ville Syrjälä <[email protected]>

The indexed write instruction doesn't support byte-enables, so
if the non-indexed write used those we must not convert it to
an indexed write.

Signed-off-by: Ville Syrjälä <[email protected]>
---
 drivers/gpu/drm/i915/display/intel_dsb.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c 
b/drivers/gpu/drm/i915/display/intel_dsb.c
index a20ae5313d23..22c716ee75e2 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -149,7 +149,7 @@ static bool intel_dsb_prev_ins_is_write(struct intel_dsb 
*dsb,
        if (dsb->free_pos == 0)
                return false;
 
-       prev_opcode = buf[dsb->ins_start_offset + 1] >> DSB_OPCODE_SHIFT;
+       prev_opcode = buf[dsb->ins_start_offset + 1] & ~DSB_REG_VALUE_MASK;
        prev_reg = buf[dsb->ins_start_offset + 1] & DSB_REG_VALUE_MASK;
 
        return prev_opcode == opcode && prev_reg == i915_mmio_reg_offset(reg);
@@ -157,12 +157,18 @@ static bool intel_dsb_prev_ins_is_write(struct intel_dsb 
*dsb,
 
 static bool intel_dsb_prev_ins_is_mmio_write(struct intel_dsb *dsb, i915_reg_t 
reg)
 {
-       return intel_dsb_prev_ins_is_write(dsb, DSB_OPCODE_MMIO_WRITE, reg);
+       /* only full byte-enables can be converted to indexed writes */
+       return intel_dsb_prev_ins_is_write(dsb,
+                                          DSB_OPCODE_MMIO_WRITE << 
DSB_OPCODE_SHIFT |
+                                          DSB_BYTE_EN << DSB_BYTE_EN_SHIFT,
+                                          reg);
 }
 
 static bool intel_dsb_prev_ins_is_indexed_write(struct intel_dsb *dsb, 
i915_reg_t reg)
 {
-       return intel_dsb_prev_ins_is_write(dsb, DSB_OPCODE_INDEXED_WRITE, reg);
+       return intel_dsb_prev_ins_is_write(dsb,
+                                          DSB_OPCODE_INDEXED_WRITE << 
DSB_OPCODE_SHIFT,
+                                          reg);
 }
 
 /**
-- 
2.39.3

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