[PATCH v1 0/9] drm/bridge: tc358768: various fixes on PLL calculation and DSI timings

From: Francesco Dolcini
Date: Thu Apr 27 2023 - 10:30:29 EST


From: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>

This series includes multiple fixes on the tc358768 parallel RGB to DSI driver.

With the following changes I am able to have a stable display output using a TI
SN65DSI83 (DSI-LVDS bridge) and a 1280 x 800 LVDS display panel and the
register values are coherent with Toshiba documentation and configuration
spreadsheet, I was not able to test any other display sink.

= DSI Video Mode =

The driver uses the MIPI_DSI_MODE_LPM flag not correctly, because of that no HS
Video is sent at all when this flag is set by the DSI slave.

= DSI Timing Parameters =

Multiple DSI timing parameters are not correct and this was leading to black or
not stable images on some display output. The new formulas were verified with
the datasheet and a configuration spread sheet from Toshiba.

I did split the change in multiple commits, I can squash all of them together
if this is considered better for any reason, including bisect-ability.

= PLL computation =

Two issues on the PLL computation, one is a required fix to have the bridge
working when the parallel RGB input width is not 24, the second one is just
following a prescription from the Toshiba documentation. In my test it was not
making any difference.

Francesco Dolcini (9):
drm/bridge: tc358768: always enable HS video mode
drm/bridge: tc358768: fix PLL parameters computation
drm/bridge: tc358768: fix PLL target frequency
drm/bridge: tc358768: fix TCLK_ZEROCNT computation
drm/bridge: tc358768: fix TCLK_TRAILCNT computation
drm/bridge: tc358768: fix THS_ZEROCNT computation
drm/bridge: tc358768: fix TXTAGOCNT computation
drm/bridge: tc358768: fix THS_TRAILCNT computation
drm/bridge: tc358768: remove unused variable

drivers/gpu/drm/bridge/tc358768.c | 53 +++++++++++++++++--------------
1 file changed, 30 insertions(+), 23 deletions(-)

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2.25.1