JFYI Jani and Ben: I will be pushing this patch to drm-misc-next sometime
today if there's no objections
On Wed, 2021-04-28 at 19:43 -0400, Nikola Cornij wrote:
> [why]
> DP 1.4a spec madates that if DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT is
> set, Extended Base Receiver Capability DPCD space must be used. Without
> doing that, the three DPCD values that differ will be wrong, leading to
> incorrect or limited functionality. MST link rate, for example, could
> have a lower value. Also, Synaptics quirk wouldn't work out well when
> Extended DPCD was not read, resulting in no DSC for such hubs.
>
> [how]
> Modify MST topology manager to use the values from Extended DPCD where
> applicable.
>
> To prevent regression on the sources that have a lower maximum link rate
> capability than MAX_LINK_RATE from Extended DPCD, have the drivers
> supply maximum lane count and rate at initialization time.
>
> This also reverts 'commit 2dcab875e763 ("Revert drm/dp_mst: Retrieve
> extended DPCD caps for topology manager")', brining the change back to
> the original 'commit ad44c03208e4 ("drm/dp_mst: Retrieve extended DPCD
> caps for topology manager")'.
>
> Signed-off-by: Nikola Cornij <nikola.cornij@xxxxxxx>
> ---
> .../display/amdgpu_dm/amdgpu_dm_mst_types.c | 5 +++
> .../gpu/drm/amd/display/dc/core/dc_link_dp.c | 18 ++++++++++
> drivers/gpu/drm/amd/display/dc/dc_link.h | 2 ++
> drivers/gpu/drm/drm_dp_mst_topology.c | 33 ++++++++++++-------
> drivers/gpu/drm/i915/display/intel_dp_mst.c | 6 +++-
> drivers/gpu/drm/nouveau/dispnv50/disp.c | 3 +-
> drivers/gpu/drm/radeon/radeon_dp_mst.c | 7 ++++
> include/drm/drm_dp_mst_helper.h | 12 ++++++-
> 8 files changed, 71 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> index 997567f6f0ba..b7e01b6fb328 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> @@ -429,6 +429,8 @@ void amdgpu_dm_initialize_dp_connector(struct
> amdgpu_display_manager *dm,
> struct amdgpu_dm_connector
> *aconnector,
> int link_index)
> {
> + struct dc_link_settings max_link_enc_cap = {0};
> +
> aconnector->dm_dp_aux.aux.name =
> kasprintf(GFP_KERNEL, "AMDGPU DM aux hw bus %d",
> link_index);
> @@ -443,6 +445,7 @@ void amdgpu_dm_initialize_dp_connector(struct
> amdgpu_display_manager *dm,
> if (aconnector->base.connector_type == DRM_MODE_CONNECTOR_eDP)
> return;
>
> + dc_link_dp_get_max_link_enc_cap(aconnector->dc_link,
> &max_link_enc_cap);
> aconnector->mst_mgr.cbs = &dm_mst_cbs;
> drm_dp_mst_topology_mgr_init(
> &aconnector->mst_mgr,
> @@ -450,6 +453,8 @@ void amdgpu_dm_initialize_dp_connector(struct
> amdgpu_display_manager *dm,
> &aconnector->dm_dp_aux.aux,
> 16,
> 4,
> + max_link_enc_cap.lane_count,
> + max_link_enc_cap.link_rate,
> aconnector->connector_id);
>
> drm_connector_attach_dp_subconnector_property(&aconnector->base);
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
> b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
> index 7d2e433c2275..6fe66b7ee53e 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
> @@ -1894,6 +1894,24 @@ bool dc_link_dp_sync_lt_end(struct dc_link *link,
> bool link_down)
> return true;
> }
>
> +bool dc_link_dp_get_max_link_enc_cap(const struct dc_link *link, struct
> dc_link_settings *max_link_enc_cap)
> +{
> + if (!max_link_enc_cap) {
> + DC_LOG_ERROR("%s: Could not return max link encoder caps",
> __func__);
> + return false;
> + }
> +
> + if (link->link_enc->funcs->get_max_link_cap) {
> + link->link_enc->funcs->get_max_link_cap(link->link_enc,
> max_link_enc_cap);
> + return true;
> + }
> +
> + DC_LOG_ERROR("%s: Max link encoder caps unknown", __func__);
> + max_link_enc_cap->lane_count = 1;
> + max_link_enc_cap->link_rate = 6;
> + return false;
> +}
> +
> static struct dc_link_settings get_max_link_cap(struct dc_link *link)
> {
> struct dc_link_settings max_link_cap = {0};
> diff --git a/drivers/gpu/drm/amd/display/dc/dc_link.h
> b/drivers/gpu/drm/amd/display/dc/dc_link.h
> index b0013e674864..cb6d0543d839 100644
> --- a/drivers/gpu/drm/amd/display/dc/dc_link.h
> +++ b/drivers/gpu/drm/amd/display/dc/dc_link.h
> @@ -346,6 +346,8 @@ bool dc_link_dp_set_test_pattern(
> const unsigned char *p_custom_pattern,
> unsigned int cust_pattern_size);
>
> +bool dc_link_dp_get_max_link_enc_cap(const struct dc_link *link, struct
> dc_link_settings *max_link_enc_cap);
> +
> void dc_link_enable_hpd_filter(struct dc_link *link, bool enable);
>
> bool dc_link_is_dp_sink_present(struct dc_link *link);
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 5539a91b4031..31d9f3ff0d39 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -3708,19 +3708,24 @@ int drm_dp_mst_topology_mgr_set_mst(struct
> drm_dp_mst_topology_mgr *mgr, bool ms
> /* set the device into MST mode */
> if (mst_state) {
> struct drm_dp_payload reset_pay;
> + int lane_count;
> + int link_rate;
>
> WARN_ON(mgr->mst_primary);
>
> /* get dpcd info */
> - ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd,
> DP_RECEIVER_CAP_SIZE);
> - if (ret != DP_RECEIVER_CAP_SIZE) {
> - drm_dbg_kms(mgr->dev, "failed to read DPCD\n");
> + ret = drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd);
> + if (ret < 0) {
> + drm_dbg_kms(mgr->dev, "%s: failed to read DPCD, ret
> %d\n",
> + mgr->aux->name, ret);
> goto out_unlock;
> }
>
> + lane_count = min_t(int, mgr->dpcd[2] &
> DP_MAX_LANE_COUNT_MASK, mgr->max_lane_count);
> + link_rate = min_t(int, mgr->dpcd[1], mgr->max_link_rate);
> mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr,
> -
> drm_dp_bw_code_to_link
> _rate(mgr->dpcd[1]),
> - mgr->dpcd[2] &
> DP_MAX_LANE_COUNT_MASK);
> + drm_dp_bw_code_to_li
> nk_rate(link_rate),
> + lane_count);
> if (mgr->pbn_div == 0) {
> ret = -EINVAL;
> goto out_unlock;
> @@ -5448,14 +5453,17 @@ EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
> * @aux: DP helper aux channel to talk to this device
> * @max_dpcd_transaction_bytes: hw specific DPCD transaction limit
> * @max_payloads: maximum number of payloads this GPU can source
> + * @max_lane_count: maximum number of lanes this GPU supports
> + * @max_link_rate: maximum link rate this GPU supports, units as in DPCD
> * @conn_base_id: the connector object ID the MST device is connected to.
> *
> * Return 0 for success, or negative error code on failure
> */
> int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
> struct drm_device *dev, struct drm_dp_aux
> *aux,
> - int max_dpcd_transaction_bytes,
> - int max_payloads, int conn_base_id)
> + int max_dpcd_transaction_bytes, int
> max_payloads,
> + int max_lane_count, int max_link_rate,
> + int conn_base_id)
> {
> struct drm_dp_mst_topology_state *mst_state;
>
> @@ -5490,6 +5498,8 @@ int drm_dp_mst_topology_mgr_init(struct
> drm_dp_mst_topology_mgr *mgr,
> mgr->aux = aux;
> mgr->max_dpcd_transaction_bytes = max_dpcd_transaction_bytes;
> mgr->max_payloads = max_payloads;
> + mgr->max_lane_count = max_lane_count;
> + mgr->max_link_rate = max_link_rate;
> mgr->conn_base_id = conn_base_id;
> if (max_payloads + 1 > sizeof(mgr->payload_mask) * 8 ||
> max_payloads + 1 > sizeof(mgr->vcpi_mask) * 8)
> @@ -5896,14 +5906,13 @@ struct drm_dp_aux
> *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
> if (drm_dp_has_quirk(&desc, DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD)
> &&
> port->mgr->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14 &&
> port->parent == port->mgr->mst_primary) {
> - u8 downstreamport;
> + u8 dpcd_ext[DP_RECEIVER_CAP_SIZE];
>
> - if (drm_dp_dpcd_read(&port->aux, DP_DOWNSTREAMPORT_PRESENT,
> - &downstreamport, 1) < 0)
> + if (drm_dp_read_dpcd_caps(port->mgr->aux, dpcd_ext) < 0)
> return NULL;
>
> - if ((downstreamport & DP_DWN_STRM_PORT_PRESENT) &&
> - ((downstreamport & DP_DWN_STRM_PORT_TYPE_MASK)
> + if ((dpcd_ext[DP_DOWNSTREAMPORT_PRESENT] &
> DP_DWN_STRM_PORT_PRESENT) &&
> + ((dpcd_ext[DP_DOWNSTREAMPORT_PRESENT] &
> DP_DWN_STRM_PORT_TYPE_MASK)
> != DP_DWN_STRM_PORT_TYPE_ANALOG))
> return port->mgr->aux;
> }
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 860381d68d9d..a4245eb48ef4 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -942,6 +942,7 @@ intel_dp_mst_encoder_init(struct intel_digital_port
> *dig_port, int conn_base_id)
> struct intel_dp *intel_dp = &dig_port->dp;
> enum port port = dig_port->base.port;
> int ret;
> + int bios_max_link_rate;
>
> if (!HAS_DP_MST(i915) || intel_dp_is_edp(intel_dp))
> return 0;
> @@ -956,8 +957,11 @@ intel_dp_mst_encoder_init(struct intel_digital_port
> *dig_port, int conn_base_id)
>
> /* create encoders */
> intel_dp_create_fake_mst_encoders(dig_port);
> + bios_max_link_rate = intel_bios_dp_max_link_rate(&dig_port->base);
> ret = drm_dp_mst_topology_mgr_init(&intel_dp->mst_mgr, &i915->drm,
> - &intel_dp->aux, 16, 3,
> conn_base_id);
> + &intel_dp->aux, 16, 3,
> + dig_port->max_lanes,
> + bios_max_link_rate / 27000,
> conn_base_id);
> if (ret)
> return ret;
>
> diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> index 1c9c0cdf85db..e02f9d2d74eb 100644
> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> @@ -1617,7 +1617,8 @@ nv50_mstm_new(struct nouveau_encoder *outp, struct
> drm_dp_aux *aux, int aux_max,
> mstm->mgr.cbs = &nv50_mstm;
>
> ret = drm_dp_mst_topology_mgr_init(&mstm->mgr, dev, aux, aux_max,
> - max_payloads, conn_base_id);
> + max_payloads, outp->dcb-
> >dpconf.link_nr,
> + outp->dcb->dpconf.link_bw,
> conn_base_id);
> if (ret)
> return ret;
>
> diff --git a/drivers/gpu/drm/radeon/radeon_dp_mst.c
> b/drivers/gpu/drm/radeon/radeon_dp_mst.c
> index 59cf1d288465..8f0b2dccd199 100644
> --- a/drivers/gpu/drm/radeon/radeon_dp_mst.c
> +++ b/drivers/gpu/drm/radeon/radeon_dp_mst.c
> @@ -629,13 +629,20 @@ int
> radeon_dp_mst_init(struct radeon_connector *radeon_connector)
> {
> struct drm_device *dev = radeon_connector->base.dev;
> + int max_link_rate;
>
> if (!radeon_connector->ddc_bus->has_aux)
> return 0;
>
> + if (radeon_connector_is_dp12_capable(&radeon_connector->base))
> + max_link_rate = 0x14;
> + else
> + max_link_rate = 0x0a;
> +
> radeon_connector->mst_mgr.cbs = &mst_cbs;
> return drm_dp_mst_topology_mgr_init(&radeon_connector->mst_mgr, dev,
> &radeon_connector->ddc_bus->aux,
> 16, 6,
> + 4, max_link_rate,
> radeon_connector->base.base.id);
> }
>
> diff --git a/include/drm/drm_dp_mst_helper.h
> b/include/drm/drm_dp_mst_helper.h
> index 20dc705642bd..b5b0bf37813b 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -593,6 +593,14 @@ struct drm_dp_mst_topology_mgr {
> * @max_payloads: maximum number of payloads the GPU can generate.
> */
> int max_payloads;
> + /**
> + * @max_lane_count: maximum number of lanes the GPU can drive.
> + */
> + int max_lane_count;
> + /**
> + * @max_link_rate: maximum link rate per lane GPU can output.
> + */
> + int max_link_rate;
> /**
> * @conn_base_id: DRM connector ID this mgr is connected to. Only
> used
> * to build the MST connector path value.
> @@ -765,7 +773,9 @@ struct drm_dp_mst_topology_mgr {
> int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
> struct drm_device *dev, struct drm_dp_aux
> *aux,
> int max_dpcd_transaction_bytes,
> - int max_payloads, int conn_base_id);
> + int max_payloads,
> + int max_lane_count, int max_link_rate,
> + int conn_base_id);
>
> void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr);
>
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
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