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displayport: fix multiple dplib bugs found during exhaustive audit #2

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Merged
coleleavitt merged 3 commits into from
Feb 23, 2026
Merged

displayport: fix multiple dplib bugs found during exhaustive audit #2

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e54d510
displayport: remove redundant interlane alignment check in isLinkLost()
coleleavitt Feb 23, 2026
707526f
displayport: clamp tunnel bandwidth request to prevent NvU8 truncation
coleleavitt Feb 23, 2026
27567d7
displayport: detect RM link training fallback in MST optimized path
coleleavitt Feb 23, 2026
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29 changes: 22 additions & 7 deletions src/common/displayport/src/dp_connectorimpl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4416,7 +4416,11 @@ bool ConnectorImpl::allocateDpTunnelBw(NvU64 bandwidth)
// = DPCD Value / granularityMultiplier
// DPCD Value = bandwidth * granularityMultiplier
//
requestBw = (NvU8) divide_ceil(bandwidth * granularityMultiplier, 1000 * 1000 * 1000);
{
NvU64 rawBw = divide_ceil(bandwidth * (NvU64)granularityMultiplier,
(NvU64)1000 * 1000 * 1000);
requestBw = (rawBw > NV_U8_MAX) ? (NvU8)NV_U8_MAX : (NvU8)rawBw;
}

if (requestBw > estimatedBw)
{
Expand Down Expand Up @@ -5030,12 +5034,6 @@ bool ConnectorImpl::isLinkLost()
if (!hal->getLaneStatusChannelEqualizationDone(i))
return true;
}

if (!(hal->isDpInTunnelingSupported() && main->isDpTunnelingHwBugWarEnabled()))
{
if (!hal->getInterlaneAlignDone())
return true;
}
}
return false;
}
Expand Down Expand Up @@ -5545,6 +5543,23 @@ bool ConnectorImpl::trainLinkOptimized(LinkConfiguration lConfig)
};
}


//
// If RM fell back to a lower link config during training
// (main->train() can internally reduce lanes/rate), the DSC
// PPS parameters computed during compoundQuery for
// highestAssessedLC are now stale. Mark as failed so the
// caller does not proceed with mismatched DSC configuration.
//
if (highestAssessedLC.isValid() &&
highestAssessedLC != activeLinkConfig &&
activeLinkConfig.isValid())
{
DP_PRINTF(DP_WARNING,
"DPCONN> MST link trained at lower config than assessed;"
" DSC parameters may be stale.");
bLinkTrainingSuccessful = false;
}
lConfig = activeLinkConfig;

if (bEnteredFlushMode)
Expand Down