On Wed, Oct 01, 2014 at 03:52:42PM +0200, Arnd Bergmann wrote: > On Wednesday 01 October 2014 14:59:01 Mika Westerberg wrote: > > On Wed, Oct 01, 2014 at 12:01:34PM +0200, Arnd Bergmann wrote: > > > On Wednesday 01 October 2014 12:13:09 Mika Westerberg wrote: > > > > > > > > > Regarding the MODULE_DEVICE_TABLE, I suspect the above won't work the > > > > > way you are hoping for, because once you get to dozens or hundreds of > > > > > drivers doing this, each device will show up with the same string, > > > > > so udev will try to load all the modules that list "PRP0001". That > > > > > doesn't look right. With the code from patch 3, you can probably drop > > > > > the acpi MODULE_DEVICE_TABLE() entirely and get the correct behavior. > > > > > > > > It actually works like this now: > > > > > > > > # cd /sys/bus/platform/devices/PRP0001\:00/ > > > > DRIVER=leds-gpio > > > > MODALIAS=of:Nprp0001TacpiCgpio-leds > > > > > > > > # cat modalias > > > > of:Nprp0001TacpiCgpio-leds > > > > > > > > In other words the modalias changes to be of:Nprp0001Tacpi, e.g > > > > name=prp0001, type=acpi and then list of compatible values. > > > > > > > > Udev then loads only module that matches the modalias so it should not > > > > load everything listing PRP0001 in their MODULE_DEVICE_TABLE(). > > > > > > I'm not completely following yet. I can see how this works now, but > > > how is this better than just using the existing modalias for OF? > > > > You mean using just what of_device_get_modalias() would create? In that > > case, what do we put to name and type fields? > > Sorry, I think we're still both misunderstanding one another. You were > talking about the modalias created by the device scanning above, while > I meant the one in the MODULE_DEVICE_TABLE. Right, got it now. > With the entry you create in create_modalias(), you will only ever > match against the MODULE_DEVICE_TABLE(of, of_gpio_leds_match) > line, not against the MODULE_DEVICE_TABLE(acpi, acpi_gpio_leds_match), > so I think you can just drop the latter. Indeed. > On the question what to put into the name and type fields, that is > unrelated. The type is supposed to be for the 'device_type' property > in DT, which we should never rely on in a driver that supports both > APCI and DT. In Linux we only use that for "pci", "cpu" and "memory", > all of which have their own way of getting probed in ACPI. > The "name" is normally ignored in DT as well, except for backwards > compatibility with old bindings, but I would argue that you should not > just put "prp0001" in there. Either leave it empty like type, or use > the name of the device as it appears in the ACPI tables, such as "DEV0" > or "PWM". OK, I think it makes sense to leave them empty. I remember I tried that at some point but it didn't work without N and T fields. Is there some example what to put there in case of empty? Something like "of:N*T*Cgpio-leds" perhaps? -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
