On Wed, Aug 28, 2024 at 12:10 PM Maximilian Luz <luzmaximilian@xxxxxxxxx> wrote:
I thought I should provide some context:
Thank you, my reply below.
Am 26/08/2024 um 22:54 schrieb Andy Shevchenko:
Wed, Aug 14, 2024 at 12:27:27PM +0200, Konrad Dybcio kirjoitti:
From: Konrad Dybcio <quic_kdybcio@xxxxxxxxxxx>
[...]
nodes = (const struct software_node **)acpi_device_get_match_data(&pdev->dev);
Hmm... Why this doesn't use simple device_get_match_data()?
- if (!nodes)
- return -ENODEV;
+ if (!nodes) {
+ fdt_root = of_find_node_by_path("/");
+ if (!fdt_root)
+ return -ENODEV;
+
+ match = of_match_node(ssam_platform_hub_of_match, fdt_root);
+ of_node_put(fdt_root);
+ if (!match)
+ return -ENODEV;
+
+ nodes = (const struct software_node **)match->data;
This is quite strange! Where are they being defined?
Essentially, this whole module is a giant workaround because there
doesn't seem to be a way to auto-discover which functions or subdevices
the EC actually supports. So this module builds a registry of software
nodes and matches against a Surface-model-specific ACPI ID (in ACPI
mode). Based on that ID, we retrieve the tree of software nodes that
define the EC subdevices and register them using a (virtual) platform
hub device.
The snippet way above registers the platform hub device for DT,
because there we don't have an equivalent ACPI device that we can
use. The code here retrieves the respective nodes.
Yes, and software nodes for DT are quite strange things! Why can't you
simply fix the DT to begin with?
+ if (!nodes)
+ return -ENODEV;
+ }
...
+MODULE_ALIAS("platform:surface_aggregator_platform_hub");
Can it be platfrom device ID table instead? But do you really need it?
I think the explanation above already kind of answers this, but the
module is named differently than the driver (so that they reflect the
specific nature of each, registry vs hub device). And the platform hub
device added in the snippet I left above is named after the driver. So
for the registry module to load when the platform hub driver is
requested, it is needed.
So, I believe it warrants a platform device ID table to make it explicit.