From 05877a83211aee64a47e227dde433ef19fec0b2e Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Thu, 28 Apr 2022 02:23:18 +0200
Subject: [PATCH] backends/drm: reduce "max bpc" to what is actually used

This prevents triggering a bug in the BenQ GW2765 monitor, and should
in theory have no downsides.

BUG: 449906
FIXED-IN: 5.24.5
---
 src/backends/drm/drm_pipeline.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/backends/drm/drm_pipeline.cpp b/src/backends/drm/drm_pipeline.cpp
index 8d3bc34200..afc3812dcb 100644
--- a/src/backends/drm/drm_pipeline.cpp
+++ b/src/backends/drm/drm_pipeline.cpp
@@ -231,7 +231,11 @@ void DrmPipeline::prepareAtomicModeset()
         m_connector->getProp(DrmConnector::PropertyIndex::Underscan_hborder)->setPending(hborder);
     }
     if (const auto bpc = m_connector->getProp(DrmConnector::PropertyIndex::MaxBpc)) {
-        bpc->setPending(bpc->maxValue());
+        uint64_t preferred = 8;
+        if (auto backend = dynamic_cast<EglGbmBackend *>(gpu()->platform()->renderBackend()); backend && backend->prefer10bpc()) {
+            preferred = 10;
+        }
+        bpc->setPending(std::min(bpc->maxValue(), preferred));
     }
 
     m_pending.crtc->setPending(DrmCrtc::PropertyIndex::Active, activePending());