Olof, Anton, Care to pitch in? Thanks, Frans On Thu, Sep 25, 2014 at 11:32 AM, Frans Klaver <fransklaver@xxxxxxxxx> wrote: > On Thu, Sep 25, 2014 at 11:27 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote: >> 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. > > Exactly. I can imagine this really being a problem if the i2c bus > already has a lot of priority traffic. > > Frans -- 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
