Re: [PATCH v1] drm/bridge: ti-sn65dsi86: Transition to LP mode on every video line

[Doug Anderson]

Hi,

On Tue, Sep 16, 2025 at 7:22 AM Emanuele Ghidoli
<ghidoliemanuele@xxxxxxxxx> wrote:
>
> From: Emanuele Ghidoli <emanuele.ghidoli@xxxxxxxxxxx>
>
> The component datasheet recommends, to reduce power consumption,
> transitioning to LP mode on every video line.
>
> Enable the MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP
> flags so that the bridge can enter LP mode during the horizontal front
> porch and back porch periods.
>
> Signed-off-by: Emanuele Ghidoli <emanuele.ghidoli@xxxxxxxxxxx>
> ---
> Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
> Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
> Cc: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
> Cc: Robert Foss <rfoss@xxxxxxxxxx>
> Cc: Laurent Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Jonas Karlman <jonas@xxxxxxxxx>
> Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Simona Vetter <simona@xxxxxxxx>
> Cc: Jayesh Choudhary <j-choudhary@xxxxxx>
> Cc: <dri-devel@xxxxxxxxxxxxxxxxxxxxx>
> Cc: <linux-kernel@xxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

I put this on a sc7180-trogdor based Chromebook and the display no
longer comes up. I don't personally know the MIPI side of the spec too
well so I have no idea why that would be.

-Doug