Re: [PATCH] drm/panel: visionox-rm69299: Make use of prepare_prev_first

[David Heidelberg]

On 17/04/2026 04:38, Doug Anderson wrote:
> Hi,
>
> On Wed, Apr 15, 2026 at 2:30 PM David Heidelberg via B4 Relay
> <devnull+david.ixit.cz@xxxxxxxxxx> wrote:
> > From: Guido Günther <agx@xxxxxxxxxxx>
> >
> > The DSI link must be powered up to let panel driver to talk to the panel
> > during prepare() callback execution. Set the prepare_prev_first flag to
> > guarantee this.
> >
> > Fixes: 9e15123eca79 ("drm/msm/dsi: Stop unconditionally powering up DSI hosts at modeset")
> > Signed-off-by: Guido Günther <agx@xxxxxxxxxxx>
> > Signed-off-by: David Heidelberg <david@xxxxxxx>
> > ---
> >   drivers/gpu/drm/panel/panel-visionox-rm69299.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/gpu/drm/panel/panel-visionox-rm69299.c b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
> > index e5e688cf98fdc..0e33454650d13 100644
> > --- a/drivers/gpu/drm/panel/panel-visionox-rm69299.c
> > +++ b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
> > @@ -387,6 +387,7 @@ static int visionox_rm69299_probe(struct mipi_dsi_device *dsi)
> >          dsi->format = MIPI_DSI_FMT_RGB888;
> >          dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_LPM |
> >                            MIPI_DSI_CLOCK_NON_CONTINUOUS;
> > +       ctx->panel.prepare_prev_first = true;
>
> Although it probably doesn't matter tons in practice, it seems like it
> would be good form to set this _before_ you call drm_panel_add(). Is
> there a reason you didn't do that?

Hello Doug,

no good reason, I'll send v2 with moved prepare_prev_first before drm_panel_add().

David>
> -Doug

--
David Heidelberg