On Mon, Mar 16, 2015 at 05:12:32PM +0000, Mark Brown wrote: > On Mon, Mar 16, 2015 at 04:58:42PM +0000, Charles Keepax wrote: > > > On the first boot of the wm5110 it is important the reset line is held > > for slightly longer to ensure the device starts up well. This patch adds > > a 5mS delay for this. > > How can we tell what first boot is - what happens if the device is fully > powered off during system suspend for example? I'd expect to see this > done for system resume as well if we don't know power was maintained (or > whatever else the distinction is).
Internally the device has some state, so effectively we define the first boot as the first time DCVDD is applied since either the last physical reset or time the core_supplies were missing. I think your suspend example is pretty tricky, we enable the regulators for the core_supplies at boot, so I guess we have requested that the system never removes those so if it does so anyway perhaps that is a system problem? There isn't really anyway to tell if they were removed, since we can't talk to the CODEC without DCVDD (even if we could I don't think we can find out) and we need to know before we power it up. Also presumably if the system removed the regulator when we told it not to it won't report anything through the regulator framework. That would leave the only possible solution being a hard reset during every runtime resume but that makes me very nervous about the AoD interrupts as state for those would be lost upon that reset. All in all, I really struggle to see what more the driver could do here. Thanks, Charles -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
