ARM: OMAP2+: hwmod: Rearm wake-up interrupts for DT when MUSB is idled

Looks like MUSB cable removal can cause wake-up interrupts to stop working for device tree based booting at least for UART3 even as nothing is dynamically remuxed. This can be fixed by calling reconfigure_io_chain() for device tree based booting in hwmod code.

Note that we already do that for legacy booting
if the legacy mux is configured.

My guess is that this is related to UART3 and MUSB ULPI hsusb0_data0 and hsusb0_data1 support for Carkit mode that somehow affect the configured IO chain for UART3 and require rearming the wake-up interrupts.

In general, for device tree based booting, pinctrl-single calls the rearm hook that in turn calls reconfigure_io_chain so calling reconfigure_io_chain should not be needed from the hwmod code for other events.

So let's limit the hwmod rearming of iochain only to HWMOD_FORCE_MSTANDBY where MUSB is currently the only user of it. If we see other devices needing similar changes we can add more checks for it.

Cc Paul Walmsley <[email protected]>

Signed-off-by Tony Lindgren <[email protected]>

arch/arm/mach-omap2/omap_hwmod.c +2 -0

@@ -2185,6 +2185,8 @@ static int _enable(struct omap_hwmod *oh)
 			 oh->mux->pads_dynamic))) {
 		omap_hwmod_mux(oh->mux, _HWMOD_STATE_ENABLED);
 		_reconfigure_io_chain();
+	} else if (oh->flags & HWMOD_FORCE_MSTANDBY) {
+		_reconfigure_io_chain();
 	}
 
 	_add_initiator_dep(oh, mpu_oh);

Quoted 5 lines · Tony Lindgren

Looks like MUSB cable removal can cause wake-up interrupts to stop working for device tree based booting at least for UART3 even as nothing is dynamically remuxed. This can be fixed by calling reconfigure_io_chain() for device tree based booting in hwmod code.

Weird, nice find. Do you know if this applies to all OMAPs, or just OMAP3?

Quoted 13 lines

Note that we already do that for legacy booting
if the legacy mux is configured.

My guess is that this is related to UART3 and MUSB ULPI hsusb0_data0 and hsusb0_data1 support for Carkit mode that somehow affect the configured IO chain for UART3 and require rearming the wake-up interrupts.

In general, for device tree based booting, pinctrl-single calls the rearm hook that in turn calls reconfigure_io_chain so calling reconfigure_io_chain should not be needed from the hwmod code for other events.

Quoted 4 lines

So let's limit the hwmod rearming of iochain only to HWMOD_FORCE_MSTANDBY where MUSB is currently the only user of it. If we see other devices needing similar changes we can add more checks for it.

Could you please add a new hwmod flag for this case? Maybe something like HWMOD_RECONFIG_IO_CHAIN? I think that would make the code easier to read and more maintainable, since the workaround would then be explicitly connected with that particular workaround's flag. Looks like we have several flag bits left. Plus if we wind up having to set HWMOD_FORCE_MSTANDBY for other devices that might not need the I/O chain reconfiguration, we won't have to reimplement this flag workaround.