[bug report] drm/msm/dpu: reserve cdm blocks for writeback in case of YUV output

[Dan Carpenter]

Hello Abhinav Kumar,

This is a semi-automatic email about new static checker warnings.

The patch 8b45a26f2ba9: "drm/msm/dpu: reserve cdm blocks for
writeback in case of YUV output" from Dec 12, 2023, leads to the
following Smatch complaint:

    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c:2084 dpu_encoder_helper_phys_cleanup()
    warn: variable dereferenced before check 'phys_enc->hw_pp' (see line 2075)

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
  2074		/* reset the merge 3D HW block */
  2075		if (phys_enc->hw_pp->merge_3d) {
                    ^^^^^^^^^^^^^^^
The existing code assumed that phys_enc->hw_pp is vald.

  2076			phys_enc->hw_pp->merge_3d->ops.setup_3d_mode(phys_enc->hw_pp->merge_3d,
  2077					BLEND_3D_NONE);
  2078			if (phys_enc->hw_ctl->ops.update_pending_flush_merge_3d)
  2079				phys_enc->hw_ctl->ops.update_pending_flush_merge_3d(ctl,
  2080						phys_enc->hw_pp->merge_3d->idx);
  2081		}
  2082	
  2083		if (phys_enc->hw_cdm) {
  2084			if (phys_enc->hw_cdm->ops.bind_pingpong_blk && phys_enc->hw_pp)
                                                                       ^^^^^^^^^^^^^^^
But the patch assumes it can be NULL.

  2085				phys_enc->hw_cdm->ops.bind_pingpong_blk(phys_enc->hw_cdm,
  2086									PINGPONG_NONE);

regards,
dan carpenter