drm/i915/dsb: Don't use indexed writes when byte enables are not all set

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 <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230606191504.18099-8-ville.syrjala@linux.intel.com
Reviewed-by: Animesh Manna <animesh.manna@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
index 3de0d572c511a729ca74a83fd05a534eff6f158c..9a507b9ad82cac753aa38168b29d933215b2fdb0 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -145,7 +145,7 @@ 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);
@@ -153,12 +153,18 @@ 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);
 }
 
 /**