Re: [PATCH 3/5] drm/bridge: simple-bridge: Allow acquiring the next bridge with fwnode API

[Sui Jingfeng]

Hi,


On 2024/1/23 09:18, Laurent Pinchart wrote:
> On Tue, Jan 23, 2024 at 12:32:18AM +0800, Sui Jingfeng wrote:
> > Which make it possible to use this driver on non-DT based systems,
> > meanwhile, made no functional changes for DT based systems.
> >
> > Signed-off-by: Sui Jingfeng <sui.jingfeng@xxxxxxxxx>
> > ---
> >   drivers/gpu/drm/bridge/simple-bridge.c | 51 ++++++++++++++++++++++----
> >   1 file changed, 44 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c
> > index 595f672745b9..cfea5a67cc5b 100644
> > --- a/drivers/gpu/drm/bridge/simple-bridge.c
> > +++ b/drivers/gpu/drm/bridge/simple-bridge.c
> > @@ -184,6 +184,39 @@ static const void *simple_bridge_get_match_data(const struct device *dev)
> >   	return NULL;
> >   }
> >   
> > +static int simple_bridge_get_next_bridge_by_fwnode(struct device *dev,
> > +						   struct drm_bridge **next_bridge)
> > +{
> > +	struct drm_bridge *bridge;
> > +	struct fwnode_handle *ep;
> > +	struct fwnode_handle *remote;
> > +
> > +	ep = fwnode_graph_get_endpoint_by_id(dev->fwnode, 1, 0, 0);
> > +	if (!ep) {
> > +		dev_err(dev, "The endpoint is unconnected\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	remote = fwnode_graph_get_remote_port_parent(ep);
> > +	fwnode_handle_put(ep);
> > +	if (!remote) {
> > +		dev_err(dev, "No valid remote node\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	bridge = drm_bridge_find_by_fwnode(remote);
> > +	fwnode_handle_put(remote);
> > +
> > +	if (!bridge) {
> > +		dev_warn(dev, "Next bridge not found, deferring probe\n");
> > +		return -EPROBE_DEFER;
> > +	}
> > +
> > +	*next_bridge = bridge;
> > +
> > +	return 0;
> > +}
> > +
> Hmmmm yes, this convinces me further that we should switch to fwnode,
> not implement fwnode and OF side-by-side.

OK, I'm agree with you.


But this means that I have to make the drm_bridge_find_by_fwnode() function works
on both DT systems and non-DT systems. This is also means that we will no longer
need to call of_drm_find_bridge() function anymore. This will eventually lead to
completely remove of_drm_find_bridge()?


As far as I can see, if I follow you suggestion, drm/bridge subsystem will
encountering a *big* refactor. My 'side-by-side' approach allows co-exist.
It is not really meant to purge OF. I feel it is a little bit of aggressive.

hello Maxime, are you watching this? what do you think?


> >   static int simple_bridge_probe(struct platform_device *pdev)
> >   {
> >   	struct simple_bridge *sbridge;
> > @@ -199,14 +232,17 @@ static int simple_bridge_probe(struct platform_device *pdev)
> >   	else
> >   		sbridge->info = simple_bridge_get_match_data(&pdev->dev);
> >   
> > -	/* Get the next bridge in the pipeline. */
> > -	remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
> > -	if (!remote)
> > -		return -EINVAL;
> > -
> > -	sbridge->next_bridge = of_drm_find_bridge(remote);
> > -	of_node_put(remote);
> > +	if (pdev->dev.of_node) {
> > +		/* Get the next bridge in the pipeline. */
> > +		remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
> > +		if (!remote)
> > +			return -EINVAL;
> >   
> > +		sbridge->next_bridge = of_drm_find_bridge(remote);
> > +		of_node_put(remote);
> > +	} else {
> > +		simple_bridge_get_next_bridge_by_fwnode(&pdev->dev, &sbridge->next_bridge);
> > +	}
> >   	if (!sbridge->next_bridge) {
> >   		dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
> >   		return -EPROBE_DEFER;
> > @@ -231,6 +267,7 @@ static int simple_bridge_probe(struct platform_device *pdev)
> >   	/* Register the bridge. */
> >   	sbridge->bridge.funcs = &simple_bridge_bridge_funcs;
> >   	sbridge->bridge.of_node = pdev->dev.of_node;
> > +	sbridge->bridge.fwnode = pdev->dev.fwnode;
> >   	sbridge->bridge.timings = sbridge->info->timings;
> >   
> >   	drm_bridge_add(&sbridge->bridge);
> > --
> > 2.25.1