On 09/03/2014 08:19 AM, Lee Jones wrote: > On Wed, 03 Sep 2014, Prarit Bhargava wrote: >> On 09/03/2014 07:35 AM, Lee Jones wrote: >>>>>> This occurs because there are two LPC devices on the system: >>>>>> >>>>>> 00:1f.0 ISA bridge: Intel Corporation 82801JIB (ICH10) LPC Interface >>>>>> Controller >>>>>> 80:1f.0 ISA bridge: Intel Corporation 82801JIB (ICH10) LPC Interface >>>>>> Controller >>>>>> >>>>>> which AFAICT is a hardware configuration error that can be resolved in >>>>>> firmware by hiding the second LPC device. Having two of these results in >>>>>> two GPIO mappings and two Watchdog Timers which doesn't make much sense. >>>>>> >>>>>> An end user has no idea what the splats mean. We should inform the user >>>>>> that >>>>>> the issue lies with the hardware and that they should contact their >>>>>> vendor >>>>>> for resolution. >>>>> >>>>> Why is it a problem for 2 of these devices to exist on a single system? >>>>> >>>>> Shouldn't the driver just be able to handle 2 devices? >>>>> >> >>>> >>>> You end up with two watchdogs on the same system (and more confusingly >>>> they use >>>> the same global interface). Additionally you end up with two sets of GPIOs >>>> which also use the same global interface ... not good. >>> >>> I understand the problem with the _driver_, but why is it a problem >>> that two of these _devices_ exist on one system? Bailing out of the >>> second .probe() sounds hacky to me. The driver should know that this >>> is possible and act accordingly, or the second devices shouldn't be >>> registered. >>> >>> Can these devices be controlled seperately? >> >> Let's just try and address this for now ... They can be controlled separately >> but that's not the issue here. >> >> Consider just the watchdog timer (because it is easier to explain). The way >> the >> watchdog timer works is that we write to it every 30 seconds (or so ... it >> depends on your setup obviously). If we don't write to it within 30 seconds >> the >> system will panic and reboot. >> >> Now ... suppose you have two on a system. To what end? It doesn't make >> sense to >> have two. Either you can write from userspace or you can't. Now you have >> two >> running with different timeouts -- why? That doesn't make sense either. It > > You only have 2 running if you start them both. > >> isn't like the one with the longer timeout is ever going to cause a reboot. >> >> Does that explain things better? It's a not a real-world scenario. > > On the h/w I'm currently working on, we have 3 Watchdogs.
"3": what are they? Are they all system-level watchdogs? I can understand the BMC having a watchdog, the system HW having a watchdog (which is what we're talking about here), and I'm sure we can think of other watchdogs ... but two that are EXACTLY the same? > >> You also asked ... >> >>> Then why do they [have two devices specified]? >> >> Because the vendor didn't/forgot to hide one from the kernel in BIOS -- hence >> FW_BUG. > > If only one is useful, why have the second one in the first place? That's just it -- it shouldn't have been exposed (again, according to Intel). > > If the devices are present and we can see them, why not have 2? Some > users might find a use for them. No one will. > > In the WARNING you submitted only sysfs was having a hard time. > Perhaps the real fix would be to allow the Watchdog and GPIO driver to > change their name when registering, so they can each have their own > sysfs entries. /me scratches head. How does that help having multiple devices which shouldn't be exposed? P. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
