Re: [PATCH v6 21/23] drm: rockchip: Add VOP2 driver

[Sascha Hauer <s.hauer@pengutronix.de>]

Hi Andy,

Please trim the context in your answers to the relevant parts, it makes
it easier to find the things you said.

On Thu, Feb 17, 2022 at 08:00:11PM +0800, Andy Yan wrote:
> Hi Sascha:
> 
> > +
> > +	drm_for_each_encoder_mask(encoder, crtc->dev, crtc_state->encoder_mask) {
> > +		struct rockchip_encoder *rkencoder = to_rockchip_encoder(encoder);
> > +		struct device_node *node, *parent;
> > +
> > +		parent = of_get_parent(rkencoder->port);
> > +
> > +		for_each_endpoint_of_node(parent, node) {
> 
> Is there any hurt directly use our downstream vendor kernel method here: use
> vcstate->output_if set by encoder driver to get which interface we should
> enable here?

There is no vcstate->output_if in mainline currently. Ok, we could add
that. The other thing is that there are multiple HDMI interfaces and
the id of the HDMI encoder is encoded into output_if. Downstream kernel
adds OF aliases to the HDMI ports. I didn't want to go that route
because it doesn't seem to be very elegant to me.

> 
> You method is ok with device tree,  but it tied up this driver to device
> tree, we are now tring to extend vop2 driver work with ACPI, so we hope this
> driver can be much more flexible.

The current rockchip drm driver seems to be pretty much tied to device
tree. There are probably many other places that need parallel paths for
ACPI support, I think we can delay this particular part until we see the
whole picture. In the end we can still retrieve the output_if
information differently with ACPI while still retrieving the information
from the device tree the way we are doing currently.

Sascha


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