On Wed, Sep 24, 2014 at 07:59:34PM +0100, Frans Klaver wrote: > On Wed, Sep 24, 2014 at 04:34:32PM +0100, Mark Rutland wrote: > > On Wed, Sep 24, 2014 at 04:14:48PM +0100, Frans Klaver wrote: > > > On Wed, Sep 24, 2014 at 03:38:49PM +0100, Mark Rutland wrote: > > > > On Wed, Sep 24, 2014 at 03:22:22PM +0100, Frans Klaver wrote: > > > > You mention that there's a GPIO that can be used to detect the battery > > > > presence. Why can't the driver always probe and then on check for the > > > > presence of the battery dynamically using that GPIO? That should cover > > > > both cases. > > > > > > I would say that this was the case before [1] was done. The GPIO is > > > optional and if not configured, the presence or absence of the battery > > > is detected by checking a status register much like probe() currently > > > does. It seems all cases were covered before that patch. If you worry > > > about speed, you should use the GPIO. I wonder if we might be able to > > > revert [1] without doing much harm. > > > > But reverting that would re-introduce the lag on some systems, no? Given > > the wording of the original commit I would guess that the GPIO wasn't > > available. Perhaps Olof or Anton can enlighten us? > > It probably would yes. The battery_detect gpio was last touched in 2011, the > probe check was added somewhere in 2012. We can't revert it unless we know doing so won't reintroduce the problem. From the above it sounds like we can't revert it. > We could keep it as a compile option. Perhaps. > > In the cases where a GPIO is available, I think we should be able to be > > less pessimistic. Is a GPIO available in your case? > > We don't have the battery_detect pin available. Incidentally, a bit of > lag reading out the battery is not a problem for us. So now we're back at sqaure one. The hardware is likely identical in the your case and the care-about-lag case. Whether or not you care about lag is a property of the user rather than the HW, so I don't think that belongs in the dt. It would be interesting to know what the lag was adversely affecting. Perhaps there's another way around this. Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
