On 16/09/2025 16:45, Doug Anderson wrote:
> Hi,
>
> On Tue, Sep 16, 2025 at 7:22 AM Emanuele Ghidoli
> <[email protected]> wrote:
>>
>> From: Emanuele Ghidoli <[email protected]>
>>
>> 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 <[email protected]>
>> ---
>> Cc: Douglas Anderson <[email protected]>
>> Cc: Andrzej Hajda <[email protected]>
>> Cc: Neil Armstrong <[email protected]>
>> Cc: Robert Foss <[email protected]>
>> Cc: Laurent Pinchart <[email protected]>
>> Cc: Jonas Karlman <[email protected]>
>> Cc: Jernej Skrabec <[email protected]>
>> Cc: Maarten Lankhorst <[email protected]>
>> Cc: Maxime Ripard <[email protected]>
>> Cc: Thomas Zimmermann <[email protected]>
>> Cc: David Airlie <[email protected]>
>> Cc: Simona Vetter <[email protected]>
>> Cc: Jayesh Choudhary <[email protected]>
>> Cc: <[email protected]>
>> Cc: <[email protected]>
>> ---
>> 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
Hi Doug,
thanks for the test.
According to the datasheet, LP is recommended for the front porch and optional
for the back porch.
Could you please run another test by keeping only MIPI_DSI_MODE_VIDEO_NO_HFP
and removing MIPI_DSI_MODE_VIDEO_NO_HBP?
dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_NO_HFP;
Kind regards,
Emanuele
