Hi, > On Thu, Jan 21, 2016 at 12:33:11PM +0100, Lothar Waßmann wrote: > > > On Thu, Jan 21, 2016 at 11:26:11AM +0100, Lothar Waßmann wrote: > > > > > On Thu, Jan 21, 2016 at 08:05:24AM +0100, Lothar Waßmann wrote: > > > > > > > On Wed, Jan 20, 2016 at 01:29:51PM +0100, Lothar Waßmann wrote: > > > > > > > > > This pin is used as IRQ pin for the LTC3589 PMIC on the Ka-Ro > > > > > > > > electronics TX48 module. Make the IRQ optional in the driver > > > > > > > > and use a > > > > > > > > polling routine instead if no IRQ is specified in DT. > > > > > > > > Otherwise the driver will continuously generate interrupts and > > > > > > > > make > > > > > > > > the system unusable. > > > It won't. That's the whole purpose of this patch. > > I'm afraid, I don't quite understand what you want to say... > > Your commit message (quoted above) claims that without this patch if no > interrupt is supplied then the unsupplied interrupt will somehow be left > screaming and make the system unusable. This doesn't make sense, if > there is no interrupt there is nothing to scream. > "Otherwise" meant the case where the IRQ is specified in DT as is currently required to get the driver loaded at all.
> > Without this patch there will be a constantly active interrupt, which > > will stall the system because the nNMI interrupt (on the EXTINTn pin) is > > level triggered. > > Since the polarity of the interrupt input is fixed, there is no way to > > use it in our HW. > > So, contrary to what you've been saying, the interrupt is actually > connected (and worse, connected to a NMI) but apparently not described > in DT. Why is it sensible to make the driver poll (which will affect > all systems using this device, even those that don't care) and not just > describe the interrupt in DT so it can be handled promptly in the normal > fashion? Presumably this will run into serious problems if the > interrupt actually fires at runtime since the NMI will scream, it's not > clear to me how the poll will manage to run successfully in that case. > Currently the driver won't even load without an IRQ specified in DT. My patch makes it possible to use the driver without requiring an IRQ! Lothar Waßmann
