diff options
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_dp_mst.c | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c index 6fd0511ab7dd..06fa0641f78f 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c @@ -207,6 +207,7 @@ static int intel_dp_mst_find_vcpi_slots_for_bpp(struct intel_encoder *encoder, int remote_bw_overhead; int link_bpp_x16; int remote_tu; + fixed20_12 pbn; drm_dbg_kms(&i915->drm, "Trying bpp %d\n", bpp); @@ -237,11 +238,29 @@ static int intel_dp_mst_find_vcpi_slots_for_bpp(struct intel_encoder *encoder, * crtc_state->dp_m_n.tu), provided that the driver doesn't * enable SSC on the corresponding link. */ - crtc_state->pbn = intel_dp_mst_calc_pbn(adjusted_mode->crtc_clock, - link_bpp_x16, - remote_bw_overhead); + pbn.full = dfixed_const(intel_dp_mst_calc_pbn(adjusted_mode->crtc_clock, + link_bpp_x16, + remote_bw_overhead)); + remote_tu = DIV_ROUND_UP(pbn.full, mst_state->pbn_div.full); - remote_tu = DIV_ROUND_UP(dfixed_const(crtc_state->pbn), mst_state->pbn_div.full); + /* + * Aligning the TUs ensures that symbols consisting of multiple + * (4) symbol cycles don't get split between two consecutive + * MTPs, as required by Bspec. + * TODO: remove the alignment restriction for 128b/132b links + * on some platforms, where Bspec allows this. + */ + remote_tu = ALIGN(remote_tu, 4 / crtc_state->lane_count); + + /* + * Also align PBNs accordingly, since MST core will derive its + * own copy of TU from the PBN in drm_dp_atomic_find_time_slots(). + * The above comment about the difference between the PBN + * allocated for the whole path and the TUs allocated for the + * first branch device's link also applies here. + */ + pbn.full = remote_tu * mst_state->pbn_div.full; + crtc_state->pbn = dfixed_trunc(pbn); drm_WARN_ON(&i915->drm, remote_tu < crtc_state->dp_m_n.tu); crtc_state->dp_m_n.tu = remote_tu; |