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

[Sebastian Reichel <sebastian.reichel@collabora.com>]

[-- Attachment #1: Type: text/plain, Size: 1237 bytes --]

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.

Greetings,

-- Sebastian

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]