On Thu, Dec 16, 2021 at 04:05:48PM +0200, Jani Nikula wrote:
> 128b/132b supports using 64 slots starting from 0, while 8b/10b reserves
> slot 0 for metadata.
>
> Commit d6c6a76f80a1 ("drm: Update MST First Link Slot Information Based
> on Encoding Format") added support for updating the topology state
> accordingly, and commit 41724ea273cd ("drm/amd/display: Add DP 2.0 MST
> DM Support") started using it in the amd driver.
>
> This feels more than a little cumbersome, especially updating the
> information in atomic check. For i915, add the update to MST connector
> .atomic_check hook rather than iterating over all MST managers and
> connectors in global mode config .atomic_check. Fingers crossed.
>
> Cc: Bhawanpreet Lakha <bhawanpreet.la...@amd.com>
> Cc: Lyude Paul <ly...@redhat.com>
> Cc: Uma Shankar <uma.shan...@intel.com>
> Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nik...@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_dp_mst.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index b8bc7d397c81..d13c7952a8d6 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -302,6 +302,8 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
> if (!old_conn_state->crtc)
> return 0;
>
> + mgr =
> &enc_to_mst(to_intel_encoder(old_conn_state->best_encoder))->primary->dp.mst_mgr;
> +
> /* We only want to free VCPI if this state disables the CRTC on this
> * connector
> */
> @@ -309,6 +311,15 @@ intel_dp_mst_atomic_check(struct drm_connector
> *connector,
> struct intel_crtc *crtc = to_intel_crtc(new_crtc);
> struct intel_crtc_state *crtc_state =
> intel_atomic_get_new_crtc_state(state, crtc);
> + struct drm_dp_mst_topology_state *topology_state;
> + u8 link_coding_cap = intel_dp_is_uhbr(crtc_state) ?
> + DP_CAP_ANSI_128B132B : DP_CAP_ANSI_8B10B;
This is too early. We haven't determined the link rate yet.
So intel_dp_mst_compute_config() is the earliest we can do this.
> +
> + topology_state =
> drm_atomic_get_mst_topology_state(&state->base, mgr);
> + if (IS_ERR(topology_state))
> + return PTR_ERR(topology_state);
> +
> + drm_dp_mst_update_slots(topology_state, link_coding_cap);
>
> if (!crtc_state ||
> !drm_atomic_crtc_needs_modeset(&crtc_state->uapi) ||
> @@ -316,7 +327,6 @@ intel_dp_mst_atomic_check(struct drm_connector *connector,
> return 0;
> }
>
> - mgr =
> &enc_to_mst(to_intel_encoder(old_conn_state->best_encoder))->primary->dp.mst_mgr;
> ret = drm_dp_atomic_release_vcpi_slots(&state->base, mgr,
> intel_connector->port);
>
> @@ -357,6 +367,7 @@ static void intel_mst_disable_dp(struct
> intel_atomic_state *state,
> struct intel_connector *connector =
> to_intel_connector(old_conn_state->connector);
> struct drm_i915_private *i915 = to_i915(connector->base.qdev);
> + int start_slot = intel_dp_is_uhbr(old_crtc_state) ? 0 : 1;a
> int ret;
>
> drm_dbg_kms(&i915->drm, "active links %d\n",
> @@ -366,7 +377,7 @@ static void intel_mst_disable_dp(struct
> intel_atomic_state *state,
>
> drm_dp_mst_reset_vcpi_slots(&intel_dp->mst_mgr, connector->port);
>
> - ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, 1);
> + ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, start_slot);
I supoose what we should do in these places is grab the new/old
mst state and dig the slot info out from it. Or I guess even better
to just pass in the whole mst_state and let the mst code dig out what
it needs.
> if (ret) {
> drm_dbg_kms(&i915->drm, "failed to update payload %d\n", ret);
> }
> @@ -475,6 +486,7 @@ static void intel_mst_pre_enable_dp(struct
> intel_atomic_state *state,
> struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> struct intel_connector *connector =
> to_intel_connector(conn_state->connector);
> + int start_slot = intel_dp_is_uhbr(pipe_config) ? 0 : 1;
> int ret;
> bool first_mst_stream;
>
> @@ -509,7 +521,7 @@ static void intel_mst_pre_enable_dp(struct
> intel_atomic_state *state,
>
> intel_dp->active_mst_links++;
>
> - ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, 1);
> + ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, start_slot);
>
> /*
> * Before Gen 12 this is not done as part of
> --
> 2.30.2
--
Ville Syrjälä
Intel
