The patch below does not apply to the 6.8-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Thanks, Sasha

------------------ original commit in Linus's tree ------------------

From 6061811d72e14f41f71b6a025510920b187bfcca Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= ville.syrjala@linux.intel.com Date: Thu, 8 Feb 2024 17:45:52 +0200 Subject: [PATCH] drm/i915/dp: Limit SST link rate to <=8.1Gbps MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

Limit the link rate to HBR3 or below (<=8.1Gbps) in SST mode. UHBR (10Gbps+) link rates require 128b/132b channel encoding which we have not yet hooked up into the SST/no-sideband codepaths.

Cc: stable@vger.kernel.org Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20240208154552.14545-1-ville.s... Reviewed-by: Jani Nikula jani.nikula@intel.com --- drivers/gpu/drm/i915/display/intel_dp.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c index ab415f41924d7..5045c34a16be1 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -2356,6 +2356,9 @@ intel_dp_compute_config_limits(struct intel_dp *intel_dp, limits->min_rate = intel_dp_common_rate(intel_dp, 0); limits->max_rate = intel_dp_max_link_rate(intel_dp);

+ /* FIXME 128b/132b SST support missing */ + limits->max_rate = min(limits->max_rate, 810000); + limits->min_lane_count = 1; limits->max_lane_count = intel_dp_max_lane_count(intel_dp);