[PATCH v3 0/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Sudarshan Shetty]

Hi all,
 
This patch refines dual-link LVDS support in the SN65DSI83/84
DSI-to-LVDS bridge driver.
 
Recent upstream changes added support for dual-link LVDS timing
adjustments and related fixes:
 - Halving horizontal timing parameters
 - Test pattern handling adjustments
 - DSI clock range correction
 
However, during validation on our platform, LVDS output remained
unstable for certain panels due to the DSI mode configuration.
 
Specifically, the following flags were found to cause issues:
 
 - MIPI_DSI_MODE_VIDEO_NO_HFP
 - MIPI_DSI_MODE_VIDEO_NO_HBP
 
These disable transmission of horizontal front porch (HFP) and
back porch (HBP) timings over the DSI link. The SN65DSI bridge
relies on complete horizontal timing information to reconstruct
LVDS timings, and omitting these parameters results in incorrect
or unstable output.
 
Additionally:
 
 - MIPI_DSI_MODE_VIDEO_BURST
 
While supported by the hardware, burst mode operation depends on
continuous clocking from the DSI host. In practice, this may lead
to instability depending on the host controller implementation,
as the link may transition to LP mode between bursts.
 
Removing these flags ensures that:
 - Full timing information is transmitted
 - The bridge can correctly reconstruct LVDS timings
 - Output remains stable across tested panels
 
This patch updates the DSI mode configuration accordingly.
 
This patch is based on recent SN65DSI83 dual-link LVDS fixes:
 - https://lore.kernel.org/lkml/20260309-ti-sn65dsi83-dual-lvds-fixes-and-test-pattern-v2-1-e6aaa7e1d181@xxxxxxxxxxx/ 

Changes in v3:
 - Rebased on top of latest upstream changes
 - Dropped previously proposed dual-link DT property and related handling
   as equivalent functionality is now available upstream
 - Refined DSI mode flag configuration to ensure stable LVDS output
 - Added detailed justification for removing NO_HFP/NO_HBP and BURST mode
 
Changes in v2:
 - Introduced ti,dual-link-video-mode DT property
 - Added DT binding documentation for the new property
 - Update driver to read the DT property and apply dual-link
   configuration conditionally
 - Adjust DSI mode flags when dual-link video mode is enabled
 - Update commit messages 

Thanks,
Anusha

Sudarshan Shetty (1):
  drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

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2.34.1