arm64: dts: qcom: sm8550: correct MDSS interconnects

commit b8591df49cde459e3b84cdc0517d7bf92053d244 upstream.

SM8550 lists two interconnects for the display subsystem, mdp0-mem
(between MDP and LLCC) and mdp1-mem (between LLCC and EBI, memory).
The second interconnect is a misuse. mdpN-mem paths should be used for
several outboud MDP interconnects rather than the path between LLCC and
memory. This kind of misuse can result in bandwidth underflows, possibly
degrading picture quality as the required memory bandwidth is divided
between all mdpN-mem paths (and LLCC-EBI should not be a part of such
division).

Drop the second path and use direct MDP-EBI path for mdp0-mem until we
support separate MDP-LLCC and LLCC-EBI paths.

Fixes: d7da51db5b81 ("arm64: dts: qcom: sm8550: add display hardware devices")
Cc: stable@kernel.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20241026-fix-sm8x50-mdp-icc-v2-1-fd8ddf755acc@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm64/boot/dts/qcom/sm8550.dtsi b/arch/arm64/boot/dts/qcom/sm8550.dtsi
index bd0e927001af06a936dcebdfa779584e219cc6ca..9ecf4a7fc3287aec94f5a72f676bb10d25d8a734 100644 (file)
--- a/arch/arm64/boot/dts/qcom/sm8550.dtsi
+++ b/arch/arm64/boot/dts/qcom/sm8550.dtsi
@@ -3002,9 +3002,8 @@
 
                        power-domains = <&dispcc MDSS_GDSC>;
 
-                       interconnects = <&mmss_noc MASTER_MDP 0 &gem_noc SLAVE_LLCC 0>,
-                                       <&mc_virt MASTER_LLCC 0 &mc_virt SLAVE_EBI1 0>;
-                       interconnect-names = "mdp0-mem", "mdp1-mem";
+                       interconnects = <&mmss_noc MASTER_MDP 0 &mc_virt SLAVE_EBI1 0>;
+                       interconnect-names = "mdp0-mem";
 
                        iommus = <&apps_smmu 0x1c00 0x2>;