On Sat, 21 Feb 2009, Jean Delvare wrote: > On Sat, 21 Feb 2009 04:06:53 -0800 (PST), Trent Piepho wrote: > > The new i2c driver interface also supports a ->detect() method and a list > > of address_data to use it with. This is much more like the legacy model > > than using i2c_new_probed_device(). > > Correct. > > > I think a compatability layer than implements attach_adapter, > > detach_adapter, and detach_client using a new-style driver's detect, probe, > > remove, and address_data should not be that hard. > > Well, that's basically what Hans has been doing with > v4l2-i2c-drv-legacy.h for months now, isn't it? This is the easy part > (even though even this wasn't exactly trivial...) Last time I looked they didn't do this. They just allowed an i2c driver to provide both an old-style interface and a probe/remove interface (not detect, it wasn't around yet). I think it should be possible for a driver to provide a probe/remove/detect interface and work on old kernels with a compat layer than translates the old inform methods into the new methods. > The hard part is when you want to use pure new-style i2c binding (using > i2c_new_device() or i2c_new_probed_device()) in the upstream kernel. > There is simply no equivalent in pre-2.6.22 kernels. So no matter what Yes, that's the part that seems most difficult. But maybe it doesn't have to be such a problem? If someone writes a new driver and only wants to use i2c_new_device() style attachment, then they can just use the existing version system to mark it as 2.6.22+ or 2.6.26+ only. Don't provide backward compatibility for the driver and just avoid the problem. Just because some new embedded camera doesn't work on 2.6.18 doesn't mean everyone has to lose 2.6.18 support. Of course there are the existing drivers like tvaudio and bttv. In this case, regardless of compatibility concerns, maybe switching to entirely i2c_new_device() style attachment isn't the right thing to do? After all, if ->detect() should never be used, why is it there and why do sensor drivers use it? Don't the myriad versions of tvcards with their various i2c chips attached seemingly at random have a lot in common with motherboards and sensor chips? -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
