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Describe the bug
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Waveshare 13.3" DSI display in 4 lane mode ends up asking a CM4 for a PV timing with horizontal front porch of 320. The resulting timing appears to be an HFP of 64 (320 & 0xff).
PV feeding HDMI or DPI outputs are quite happy to take HFP > 255.
There are a couple of other PV register bits that are set differently for DSI to the others, but none immediately scream that they are a limitation.
Steps to reproduce the behaviour
dtoverlay=vc4-kms-dsi-waveshare-panel,13_3inch_4lane
kmstest --flip will report a refresh rate of 66.7Hz instead of 60Hz.
DSI analyser agrees.
Device (s)
Raspberry Pi CM4, Raspberry Pi CM4 Lite
System
Raspberry Pi OS with 6.12.33 kernel.
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