linux-kernel - RE: [RFC PATCH 1/8] drm: writeback: Refactor drm_writeback

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Message-ID: <DM3PPF208195D8D0E55A761A3C16B87BAEEE32AA@DM3PPF208195D8D.namprd11.prod.outlook.com>
Date: Wed, 13 Aug 2025 10:04:22 +0000
From: "Kandpal, Suraj" <suraj.kandpal@...el.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, Laurent Pinchart
	<laurent.pinchart@...asonboard.com>
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Subject: RE: [RFC PATCH 1/8] drm: writeback: Refactor drm_writeback_connector
 structure

> > > };
> >
> > I still don't like that. This really doesn't belong here. If anything,
> > the drm_connector for writeback belongs to drm_crtc.
> 
> Why? We already have generic HDMI field inside drm_connector. I am really
> hoping to be able to land DP parts next to it. In theory we can have a DVI-
> specific entry there (e.g. with the subconnector type).
> The idea is not to limit how the drivers subclass those structures.
> 
> I don't see a good case why WB should deviate from that design.
> 
> > If the issue is that some drivers need a custom drm_connector
> > subclass, then I'd rather turn the connector field of
> > drm_writeback_connector into a pointer.
> 
> Having a pointer requires additional ops in order to get drm_connector from
> WB code and vice versa. Having drm_connector_wb inside drm_connector
> saves us from those ops (which don't manifest for any other kind of structure).
> Nor will it take any more space since union will reuse space already taken up by
> HDMI part.
> 
> >

Seems like this thread has died. We need to get a conclusion on the design.
Laurent do you have any issue with the design given Dmitry's explanation as to why this
Design is good for drm_writeback_connector.

Regards,
Suraj Kandpal

> > > I plan to add drm_connector_dp in a similar way, covering DP needs
> > > (currently WIP).
> 
> --
> With best wishes
> Dmitry