On Mon, Jun 28, 2010 at 4:27 PM, Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> wrote: > Grant Likely <grant.likely@xxxxxxxxxxxx> writes: > > [...] > >> >>> This affects many aspects of all drivers, from register and probe (for >>> early devices/drivers too!) to all the plaform_get_resource() usage, all >>> of which assumes a platform_driver and platform_device. I didn't look >>> closely, but I didn't see if (or how) OF was handling early devices. >> >> You don't have to reimplement the entire platform bus. You could >> simply create a new bus type, but reuse all the existing platform bus >> code. All that changes is the bus type that the device and the driver >> gets registered on. Then you could easily replace only the functions >> that matter. (do a git grep platform_bus_type to see how few >> references there actually are. It looks like there are only 5 >> references to it in drivers/base/platform.c that you'd need to work >> around; in platform_device_add(), platform_driver_register(), 2 in >> platform_driver_probe(), and the register in platform_bus_init(). You >> may not even need to reimplement platform_driver_probe(). >> >> It might even be as simple as doing this: >> - pdev->dev.bus = &platform_bus_type; >> + if (!pdev->dev.bus) >> + pdev->dev.bus = &platform_bus_type; >> >> So that a different bus type can be selected at device registration >> time > > just FYI... > > as a quick proof of concept, I've done a quick hack just to prove to > myself that I could use platform_devices on a custom bus, and it indeed > works. The small patch below[1] shows the changes required to the > platform code. > > Next step was to hack up minimal custom bus code. The quickest (and > dirtiest) way was to simply memcpy platform_bus_type into my new > omap_bus_type and then override the few dev_pm_ops functions I needed[2]. > > So, with these in place, and using the dev_pm_ops functions from > $SUBJECT patch, I was able register a platform_device and > platform_driver onto my custom bus and see my custom dev_pm_ops > functions being used as expected. Nice! > While admittedly a bit hacky, at least this paves the way in my head > that this is indeed do-able, and I can take my vacation in peace without > this particular problem haunting me (too much.) indeed. It could be less hacky also by adding a platform_bus_type_init() function to the common platform code. Cheers, g. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
