[PATCH v3 0/3] drm/rockchip: dw_hdmi: Add 4k at 30 support

[Sascha Hauer]

On Mon, Feb 06, 2023 at 03:04:48PM +0100, Sascha Hauer wrote:
> On Wed, Feb 01, 2023 at 09:23:56AM +0900, FUKAUMI Naoki wrote:
> > hi,
> > 
> > I'm trying this patch series with 6.1.x kernel. it works fine on rk356x
> > based boards (ROCK 3), but it has a problem on rk3399 boards (ROCK 4).
> > 
> > on rk3399 with this patch, I can see large noise area (about one third right
> > side of the screen) at 4k at 30. 1080p works fine as same as before.
> > 
> > can someone reproduce this problem on rk3399?
> 
> Ok, I could easily reproduce the problem here.
> 
> The RK3399 has two VOPs, vopb(ig) and vopl(ittle). Only the former can
> do 4k at 30 while the latter can only do 1080p. Unfortunately vopl is used
> by default. We can force using vopb by disabling vopl in the device tree
> and get a good 4k at 30 picture then. The other possibility I found is to
> use the other CRTC with modetest. I have no idea how we could set the
> default to vopb.
> 
> I guess a first step would be to limit the maximum resolution of vopl
> to what the hardware can do. We would likely end up with 1080p by
> default then for the applications.

I did that, but the result is not what I expected. Discarding a mode in
the connector means it won't show up in the connectors list of modes.
Discarding it in the CRTC though means the mode is still exposed by the
connector, but actually trying to use it then fails.

This means when discarding the mode in the CRTC the screen stays black.

I am not sure where I should go from here.

Sascha

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |