Re: [PATCH v4 4/8] drm/panel: sw43408: Add enable/disable and reset functions

[Dmitry Baryshkov]

On Mon, 23 Feb 2026 at 15:40, David Heidelberg <david@xxxxxxx> wrote:
>
> On 06/12/2025 05:25, Dmitry Baryshkov wrote:
> > On Tue, Nov 25, 2025 at 09:29:39PM +0100, David Heidelberg via B4 Relay wrote:
> >> From: David Heidelberg <david@xxxxxxx>
> >>
> >> Introduce enable(), disable() and reset() functions.
> >>
> >> The enable() and disable() callbacks keep the symmetry in the commands
> >> sent to the panel and also make a clearer distinction between panel
> >> initialization and configuration.
> >
> > This also makes those to to be executed after starting the DSI stream.
> > Is it fine?
> >
>
> Hello Dmitry,
>
> I was wondering how the exact workflow looks, does this snippet reflect
> real world?
>
> - The path ordering should be :
> - prepare()
> - (host/controller sets up link & starts sending video / enables bridge,
> etc.)
> - enable()
> - disable()
> - (host/controller stops video / disables bridge, etc.)
> - unprepare()
> -
> - So: prepare happens before the display pipeline is driving, and enable
> happens after the pipeline is ready and stable.
> I assume in case of poorly written host or bridge drive it may not work
> like this, but in general it should?
>
> If this workflow is correct, would it make sense I would incorporate the
> phases between into the prepare/unprepare kernel docs?

There is a very precise definition of the DSI host lifecycle. Please
take a look and notice that for DSI hosts there are two different
points:
- the DSI link is started in LP mode, letting the host send commands
to the DSI sink.
- the video / CMD stream is started

For multiple reasons those two stages are separate.

>
> Thanks
> David
>
> [...]



-- 
With best wishes
Dmitry