Hi Marcel, On Mon, Jun 11, 2018 at 5:52 PM Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote: > > Hi Ricardo, > > >>>> the commit message is misleading me. If I build something with ACPI or DT support, then modinfo will show all modalias information for ACPI and DT compatible strings. What else does udev/modprobe actually need? Is something broken with the modalias export? > >>> > >>> The main purpose is to autoload drivers for devices that have been > >>> created via sysfs or another module. > >>> > >>> Eg1: We have a serial port on a standard computer that has connected a > >>> GPS module. Since it is something that is not in the ACPI nor the DT > >>> table the user will run > >>> > >>> echo serdev_gps > /sys/bus/serial/devices/serial0/new_device > >>> > >>> Eg2 module: https://github.com/ribalda/linux/blob/415bb3f0076c2b846ebe5409589b8e1e3004f55a/drivers/tty/serdev/test_platform.c > >>> > >>> Modprobe does not know what module to load for that device unless > >>> there is a matching MODULE_DEVICE_TABLE > >>> Today, we have the same functionality for i2c devices > >>> https://www.kernel.org/doc/Documentation/i2c/instantiating-devices > >> > >> but why does this have to be the driver name? I would rather say, create a generic string that describes the hardware and then use that. I think you also want the special handling, as from USB for example, that lets you reference an existing .compatible or ACPI ID as reference so that the driver_data is copied. > > > > We can choose any name, but if there are no special variants (like the > > rave-sp driver) I would prefer using the module name. We can of course > > use more names, like the part number of the the device, but it is very > > convenient to also use the module name, and other subsystems also do > > that. > > > > If you want to add specific names for this device please let me know > > and I will add them to the list. You know much more about this module > > than myself. > > if we want to use the driver name, then why not build this into the new_device handling itself instead of duplicating that name in each serdev_device_id table. What is the reference here? For example platform device do matching on driver name if I recall this correctly. We do the matching also over driver name at serdev_device_match(): if (sdrv->id_table) return !!serdev_match_id(sdrv->id_table, sdev); return strcmp(sdev->modalias, drv->name) == 0; This is just for the module autoloading > > However what is most important is that device_get_match_data() actually works. There should be no difference between DT, ACPI or a dynamic device. Agree, will take a look to this tomorrow morning. > > Regards > > Marcel > -- Ricardo Ribalda -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
