Re: [PATCH v3 drm-dp 7/8] drm/hisilicon/hibmc: Enable this hot plug detect of irq feature

[Yongbang Shi]

> On Tue, Feb 25, 2025 at 09:57:17PM +0800, Yongbang Shi wrote:
> > > On Mon, 24 Feb 2025 at 16:03, Yongbang Shi <shiyongbang@xxxxxxxxxx> wrote:
> > > > > On Sat, Feb 22, 2025 at 06:35:48PM +0800, Yongbang Shi wrote:
> > > > > > > > +static int hibmc_dp_hpd_event(struct drm_client_dev *client)
> > > > > > > > +{
> > > > > > > > +  struct hibmc_dp *dp = container_of(client, struct hibmc_dp, client);
> > > > > > > > +  struct hibmc_drm_private *priv = to_hibmc_drm_private(dp->drm_dev);
> > > > > > > > +  struct drm_display_mode *mode = &priv->crtc.state->adjusted_mode;
> > > > > > > > +  int ret;
> > > > > > > > +
> > > > > > > > +  if (dp->hpd_status) {
> > > > > > > > +          hibmc_dp_hpd_cfg(&priv->dp);
> > > > > > > > +          ret = hibmc_dp_prepare(dp, mode);
> > > > > > > > +          if (ret)
> > > > > > > > +                  return ret;
> > > > > > > > +
> > > > > > > > +          hibmc_dp_display_en(dp, true);
> > > > > > > > +  } else {
> > > > > > > > +          hibmc_dp_display_en(dp, false);
> > > > > > > > +          hibmc_dp_reset_link(&priv->dp);
> > > > > > > > +  }
> > > > > > > If I understand this correctly, you are using a separate drm_client to
> > > > > > > enable and disable the link & display. Why is it necessary? Existing
> > > > > > > drm_clients and userspace compositors use drm framework, they should be
> > > > > > > able to turn the display on and off as required.
> > > > > > Thanks for your asking, there are cfg/reset process when the connector 's pluging in/out.
> > > > > > We want to cfg DP registers again when the connector changes. Not only dp link training, but also cfg
> > > > > > the different video modes into DP registers.
> > > > > Why? The link training and mode programming should happen during
> > > > > pre_enable / enable stage (legacy or atomic).
> > > > Hi Dmitry,
> > > >
> > > > Right, that's what I'm curious about. It won't call encoder enble/disable functions when I triggered HPD.
> > > > And I'm sure the drm_connector_helper_hpd_irq_event() is called. So I add a drm_client for it.I
> > > It should be userspace, who triggers the enable/disable (or it should
> > > be the in-kernel fbdev / fbcon, which interface through the generic
> > > drm_fbdev client).
> > Right, I knew it. When I insmode my driver firstly (or restart display service), it will call disable, modeset and enable,
> > by user, but it won't call when HPD triggered .
> - Is HPD even properly delivered to userspace? What kind of compsitor
>    are you using? Is .detect working properly and reporting a correct
>    plug-in state?

Thanks for your answering. I'm not very good understanding about userspace in framework. In my opinion, when I call
this drm_connector_helper_hpd_irq_event(), the HPD will deliver to userspace.
I use Xorg, and the display service is GDM.
The .detect is called and the getting modes info is correct.
I find that it would only trigger(disable, modeset and enable), when I changed resolutions, restart display service and insmod driver.