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

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Message-Id: <20230427142934.55435-1-francesco@dolcini.it>
Date:   Thu, 27 Apr 2023 16:29:25 +0200
From:   Francesco Dolcini <francesco@...cini.it>
To:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <rfoss@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        tomi.valkeinen@...asonboard.com, dri-devel@...ts.freedesktop.org
Cc:     Francesco Dolcini <francesco.dolcini@...adex.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org
Subject: [PATCH v1 0/9] drm/bridge: tc358768: various fixes on PLL calculation and DSI timings

From: Francesco Dolcini <francesco.dolcini@...adex.com>

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(-)

-- 
2.25.1