On Thursday, October 25, 2012 10:03 AM, Ian Abbott wrote: > On 2012-10-25 17:19, Greg Kroah-Hartman wrote: >> On Thu, Oct 25, 2012 at 03:02:37PM +0100, Ian Abbott wrote: >>> Okay, I'm just looking for a final decision before redoing the >>> patches (if necessary). >>> >>> (1) Should drivers calling comedi_auto_config() directly be able to >>> pass a context value and have the same context value passed back via >>> their auto_attach() method? >> >> Yes. >> >>> (2) If 1, what is the most useful type for that context value? >> >> I think you got it right with an unsigned long. >> >>> (3) If 1, should pre-defined wrappers around comedi_auto_config() >>> such as comedi_pci_auto_config() and comedi_usb_auto_config() pass >>> pre-defined, "magic" values (which the driver will probably ignore) >>> as the context value in the driver's auto_attach() method or just >>> pass some "null" value? >> >> That's trickier. I don't know enough about the comedi layer to answer >> this, but generally, I would stay away from having anyone except the >> driver that set the value, be the ones that can do anything with the >> value. In other words, no magic flags here. >> >> If you want a "magic" flag, use a new variable for it and make it an >> enumerated type. > > It's just that if comedi_pci_auto_config() ends up calling the driver's > auto_attach() method (and that will be the only option eventually), the >context parameter value of the driver's auto_attach() method either has > To be conjured out of thin air (i.e. it's something the driver never > really asked for in the first place and probably has no interest in > unless it handles multiple types of devices such as PCI and PCMCIA), or > we'd also have to add the context parameter to comedi_pci_auto_config() > and pass it through. > > Perhaps comedi_pci_auto_config() &co. should just set the context to 0 > for now (which is really just a _different_ context value the driver > never asked for!). Ian, At this point I think you should repost an updated patch. It looks like an unsigned long type is correct for the 'context'. But, only the driver should be using this 'context'. It's the only user that really knows what it is. If you still need to pass a "magic" value for drivers that could auto attach different types of drivers, I think you need to add an additional parameter to the auto_attach() and pass it as an enumerated type. Most drivers will simply ignore both the context and the flag. The drivers that need the flag can check it to see if they need to use one of the comedi_to_* helpers to get the context from the dev->hw_dev or if the 'context' passed is the drivers private context. Hmm.. make about as much sense to me as a mud milkshake.... Regards, Hartley _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
