On Sat, Feb 10, 2007 at 08:50:27PM +0100, Rafael J. Wysocki wrote: > On Saturday, 10 February 2007 18:52, Daniel Barkalow wrote: > > On Sat, 10 Feb 2007, Rafael J. Wysocki wrote: > > > > > On Saturday, 10 February 2007 11:02, Nigel Cunningham wrote: > > > > > > > Well, the original desire was to stop new drivers getting in without > > > > proper power management. > > > > > > I know, but I agree with the argument that having a driver without the > > > suspend/resume support is better than not having the driver at all. > > > > How about if "proper power management" is defined to include the driver > > explicitly preventing suspend? It seems to me like the current problem is > > that driver writers don't think about power management at all, and the > > result is that, after suspend/resume, the system doesn't come back. It > > would be better if driver writers had to think about power management just > > enough to realize that it's not going to work, and make this information > > available to the system. At that point, it's relatively easy for the > > system to do something useful about it. > > Actually, it is easy for the driver authors to do this right now. They can > just make the .suspend() routine always return an error. > > Well, I think this is a good idea: if the device in question requires specific > power management during the suspend/resume, but it is not implemented by the > driver, we should require the author of the driver to define the .suspend() > routine that returns -ENOSYS (preferably, with an explanatory warning in > dmesg). instead of modifying all drivers to explicitly state that they don't support it, we should start with a test of the NULL pointer for .suspend which should mean exactly the same without modifying the drivers. I find it obvious that a driver which does provide a suspend function will not support it. And if some drivers (eg /dev/null) can support it anyway, it's better to change *those* drivers to explicitly mark them as compatible. regards, Willy
