Re: [PATCH v2 0/2] drm/bridge: tc358767: Fix DRM_BRIDGE_ATTACH_NO_CONNECTOR case

[Tomi Valkeinen]

On 08/11/2023 14:45, Alexander Stein wrote:
> Hi Tomi,
>
> Am Mittwoch, 8. November 2023, 12:27:21 CET schrieb Tomi Valkeinen:
> > These two patches are needed to make tc358767 work in the
> > DRM_BRIDGE_ATTACH_NO_CONNECTOR case, at least when using a DP connector.
> >
> > I have tested this with TI AM654 EVM with a tc358767 add-on card
> > connected to a DP monitor.
>
> Just a question regarding the usage of this DSI-DP bridge.
> What is the state of the DSI lanes after the DSI host has been initialized,
> but before calling atomic_pre_enable? AFAIK this bridge requires LP-11 on DSI
> at any time for accessing the AUX channel.

Good question. I don't know, as we use it in DPI mode (DPI-DP bridge). I 
guess the DSI state is undefined, as it might well be that the DSI host 
driver's (pre-)enable is the place where the DSI is powered up and 
initialized.

So you think in DSI mode this might fail, as AUX (possibly) won't work 
when calling tc_get_edid()? We could add a check there, and skip the 
tc_get_display_props() if in DSI mode. But tc_get_edid() surely won't 
work then.

It would be good if someone with a board where tc358767 is used in DSI 
mode could test this. But, of course, it'll only be testing that 
particular DSI host behavior...

 Tomi

> Best regards,
> Alexander
>
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> > ---
> > Changes in v2:
> > - Update the format negotiation patch as discussed in
> > https://lore.kernel.org/all/7ddf0edb-2925-4b7c-ad07-27c030dd0232@xxxxxx/ -
> > Link to v1:
> > https://lore.kernel.org/r/20231031-tc358767-v1-0-392081ad9f4b@ideasonboard.
> > com
> >
> > ---
> > Aradhya Bhatia (1):
> >        drm/bridge: tc358767: Add format negotiation hooks for DPI/DSI to
> > (e)DP
> >
> > Tomi Valkeinen (1):
> >        drm/bridge: tc358767: Fix link properties discovery
> >
> >   drivers/gpu/drm/bridge/tc358767.c | 32 ++++++++++++++++++++++++++++++++
> >   1 file changed, 32 insertions(+)
> > ---
> > base-commit: 9d7c8c066916f231ca0ed4e4fce6c4b58ca3e451
> > change-id: 20231031-tc358767-58e3ebdf95f0
> >
> > Best regards,