Hi Laurent, Nikita,
Quoting Laurent Pinchart (2021-12-29 23:44:29)
> Hi Nikita,
>
> Thank you for the patch.
>
> On Sat, Dec 25, 2021 at 09:31:51AM +0300, Nikita Yushchenko wrote:
> > Hotplug events reported by bridge drivers over drm_bridge_hpd_notify()
> > get ignored unless somebody calls drm_bridge_hpd_enable(). When the
> > connector for the bridge is bridge_connector, such a call is done from
> > drm_bridge_connector_enable_hpd().
> >
> > However drm_bridge_connector_enable_hpd() is never called on init paths,
> > documentation suggests that it is intended for suspend/resume paths.
>
> Hmmmm... I'm in two minds about this. The problem description is
> correct, but I wonder if HPD should be enabled unconditionally here, or
> if this should be left to display drivers to control.
> drivers/gpu/drm/imx/dcss/dcss-kms.c enables HPD manually at init time,
> other drivers don't.
>
> It feels like this should be under control of the display controller
> driver, but I can't think of a use case for not enabling HPD at init
> time. Any second opinion from anyone ?
This patch solves an issue I have where I have recently enabled HPD on
the SN65DSI86, but without this, I do not get calls to my .hpd_enable or
.hpd_disable hooks that I have added to the ti_sn_bridge_funcs.
So it needs to be enabled somewhere, and this seems reasonable to me?
It's not directly related to the display controller - as it's a factor
of the bridge?
On Falcon-V3U with HPD additions to SN65DSI86:
Tested-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
> > In result, once encoders are switched to bridge_connector,
> > bridge-detected HPD stops working.
> >
> > This patch adds a call to that API on init path.
> >
> > This fixes HDMI HPD with rcar-du + adv7513 case when adv7513 reports HPD
> > events via interrupts.
> >
> > Fixes: c24110a8fd09 ("drm: rcar-du: Use drm_bridge_connector_init() helper")
> > Signed-off-by: Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/drm_bridge_connector.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/drm_bridge_connector.c b/drivers/gpu/drm/drm_bridge_connector.c
> > index 791379816837..4f20137ef21d 100644
> > --- a/drivers/gpu/drm/drm_bridge_connector.c
> > +++ b/drivers/gpu/drm/drm_bridge_connector.c
> > @@ -369,8 +369,10 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> > connector_type, ddc);
> > drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
> >
> > - if (bridge_connector->bridge_hpd)
> > + if (bridge_connector->bridge_hpd) {
> > connector->polled = DRM_CONNECTOR_POLL_HPD;
> > + drm_bridge_connector_enable_hpd(connector);
> > + }
> > else if (bridge_connector->bridge_detect)
> > connector->polled = DRM_CONNECTOR_POLL_CONNECT
> > | DRM_CONNECTOR_POLL_DISCONNECT;
>
> --
> Regards,
>
> Laurent Pinchart
