Re: [PATCH v3 08/10] drm/rockchip: dw_dp: Add runtime PM support

[Heiko Stuebner <heiko@sntech.de>]

Am Mittwoch, 15. Juli 2026, 21:00:12 Mitteleuropäische Sommerzeit schrieb Sebastian Reichel:
> Hello Andy,
> 
> On Tue, Jul 14, 2026 at 06:08:06PM +0800, Andy Yan wrote:
> > > @@ -58,6 +59,8 @@ static void dw_dp_rockchip_hpd_sw_sel(void *data, bool
> > > force_hpd_from_sw)
> > >
> > >         dp->hpd_sel = force_hpd_from_sw;
> > >
> > > +       ACQUIRE(pm_runtime_active_auto, pm)(dp->dev);
> > 
> > This can triger  HPD irq for USB-C DP AltMode, but for a standard
> > DP port, this is no way to acquire runtime, so there will no irq
> > when plug in.
> 
> Right. I don't have any RK3588 or RK3576 system exposing a DP
> connector directly. This this is non-trivial to test for me :/
> 
> I see the following options:
> 
> 1. Only enable runtime PM when running in USB-C mode
> 2. Mux the HPD pin as GPIO to support waking up with the controller
>    being suspended; either remux when the controller is awake or use
>    the same mechanism as USB-C to do software based HPD on top of the
>    GPIO (which would allow using any GPIO as HPD).
> 3. Have a poll function, which wakes up the controller regularly to
>    check the status
> 
> I consider going for option 1 for now, which allows option 2 to be
> implemented as a follow up. Mostly to avoid that the series becomes
> as big and messy as the USBDP PHY series became.

I'd agree with that solution.
I think we can all agree that option 3 is baaaad :-) .

So with 1, functionality keeps working, and then someone can put the
special HPD handling on top later - the Rock-5-ITX does expose the DP1
(on a hdmi port)


Heiko