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drm/i915/mst: adapt intel_dp_mtp_tu_compute_config() for 128b/132b SST

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Handle 128b/132b SST in intel_dp_mtp_tu_compute_config(). The remote
bandwidth overhead and time slot allocation are only relevant for MST;
SST only needs the local bandwidth and a check that 64 slots isn't
exceeded.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b59c94b0aac2c073b0306c0a0040b26330f94260.1735912293.git.jani.nikula@intel.com
This commit is contained in:
Jani Nikula 2025-01-03 15:52:30 +02:00
parent 1ed21a66ec
commit f6971d7427
1 changed files with 58 additions and 45 deletions
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103
drivers/gpu/drm/i915/display/intel_dp_mst.c
View file

@ -257,10 +257,7 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp,
for (bpp = max_bpp; bpp >= min_bpp; bpp -= step) {
int local_bw_overhead;
int remote_bw_overhead;
int link_bpp_x16;
int remote_tu;
fixed20_12 pbn;
drm_dbg_kms(display->drm, "Trying bpp %d\n", bpp);
@ -269,57 +266,73 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp,
local_bw_overhead = intel_dp_mst_bw_overhead(crtc_state,
false, dsc_slice_count, link_bpp_x16);
remote_bw_overhead = intel_dp_mst_bw_overhead(crtc_state,
true, dsc_slice_count, link_bpp_x16);
intel_dp_mst_compute_m_n(crtc_state,
local_bw_overhead,
link_bpp_x16,
&crtc_state->dp_m_n);
/*
* The TU size programmed to the HW determines which slots in
* an MTP frame are used for this stream, which needs to match
* the payload size programmed to the first downstream branch
* device's payload table.
*
* Note that atm the payload's PBN value DRM core sends via
* the ALLOCATE_PAYLOAD side-band message matches the payload
* size (which it calculates from the PBN value) it programs
* to the first branch device's payload table. The allocation
* in the payload table could be reduced though (to
* crtc_state->dp_m_n.tu), provided that the driver doesn't
* enable SSC on the corresponding link.
*/
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, pbn_div.full);
if (intel_dp->is_mst) {
int remote_bw_overhead;
int remote_tu;
fixed20_12 pbn;
/*
* 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);
remote_bw_overhead = intel_dp_mst_bw_overhead(crtc_state,
true, dsc_slice_count, link_bpp_x16);
/*
* 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 * pbn_div.full;
/*
* The TU size programmed to the HW determines which slots in
* an MTP frame are used for this stream, which needs to match
* the payload size programmed to the first downstream branch
* device's payload table.
*
* Note that atm the payload's PBN value DRM core sends via
* the ALLOCATE_PAYLOAD side-band message matches the payload
* size (which it calculates from the PBN value) it programs
* to the first branch device's payload table. The allocation
* in the payload table could be reduced though (to
* crtc_state->dp_m_n.tu), provided that the driver doesn't
* enable SSC on the corresponding link.
*/
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, pbn_div.full);
drm_WARN_ON(display->drm, remote_tu < crtc_state->dp_m_n.tu);
crtc_state->dp_m_n.tu = remote_tu;
/*
* 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 * pbn_div.full;
drm_WARN_ON(display->drm, remote_tu < crtc_state->dp_m_n.tu);
crtc_state->dp_m_n.tu = remote_tu;
slots = drm_dp_atomic_find_time_slots(state, &intel_dp->mst_mgr,
connector->port,
dfixed_trunc(pbn));
} else {
/* Same as above for remote_tu */
crtc_state->dp_m_n.tu = ALIGN(crtc_state->dp_m_n.tu,
4 / crtc_state->lane_count);
if (crtc_state->dp_m_n.tu <= 64)
slots = crtc_state->dp_m_n.tu;
else
slots = -EINVAL;
}
slots = drm_dp_atomic_find_time_slots(state, &intel_dp->mst_mgr,
connector->port,
dfixed_trunc(pbn));
if (slots == -EDEADLK)
return slots;