On Thu, 05 Jun 2014, Grant Likely wrote: > On Thu, Jun 5, 2014 at 11:37 AM, Lee Jones <lee.jones@xxxxxxxxxx> wrote: > > On Thu, 05 Jun 2014, Grant Likely wrote: > > > >> On Wed, 4 Jun 2014 13:09:56 +0100, Lee Jones <lee.jones@xxxxxxxxxx> wrote: > >> > Currently this is a helper function for the I2C subsystem to aid the > >> > matching of non-standard compatible strings and devices which use DT > >> > and/or ACPI, but do not supply any nodes (see: [1] Method 4). However, > >> > it has been made more generic as it can be used to only make one call > >> > for drivers which support any mixture of OF, ACPI and/or I2C matching. > >> > > >> > The initial aim is for of_match_device() to be replaced by this call > >> > in all I2C device drivers. > >> > > >> > [1] Documentation/i2c/instantiating-devices > >> > > >> > Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx> > >> > >> I don't like this. It drops all type safety on the match entry > >> and the caller has no idea what it got back. > > > > Okay, so what's the best way forward? > > > > Introduce a i2c_of_match_device() call instead? > > I still think the way to do it is to emulate the missing i2c_device_id > when calling the drivers .probe() hook by having a temporary copy on > the stack and filling it with data from the OF or ACPI table.... That's the opposite of what I'm trying to achieve. I'm trying to get rid of unused i2c_device_id tables, rather than reinforce their mandatory existence. I think an i2c_of_match_device() with knowledge of how to match via pure DT principles (of_node/compatible) and a fall-back, which is able to match on a provided of_device_id table alone i.e. without the requirement of an existing of_node. I've also been mulling over the idea of removing the second probe() parameter, as suggested by Wolfram. However, this has quite deep ramifications which would require a great deal of driver adaptions. > Actually I would completely skip trying to get the data from ACPI. > Since all of this is to continue supporting instantiating devices from > sysfs, having a fallback to the OF table completely solves that use > case. > Anticipating an objection of: "what do we do with drivers that are > ACPI only?"... That will be an incredibly rare case. If that ever does > happen then we'll solve it by simply adding an of_device_id table. I'm fine with leaving out ACPI support for now. -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
