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

Sui Jingfeng
2024-01-23T12:18:29Z

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@linux.dev>
>> ---
>> 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
>>