On 03/05/2015 12:49 PM, Tony Lindgren wrote: > * Paul Walmsley <paul@xxxxxxxxx> [150305 10:16]: >> On Thu, 5 Mar 2015, Dave Gerlach wrote: >> >>> Introduce a dt property, ti,no-init, that prevents hwmod initialization. >>> Even if a dt node is marked as disabled, hwmod still at least enables >>> the hwmod and programs the sysconfig before attempting to idle it at >>> boot. If an IP has been disabled by the hardware configuration on a >>> platform, this will cause a hang due to writing to inactive registers. >>> This property prevents that from happening by marking the hwmod as >>> _HWMOD_STATE_DISABLED during init. >> >> I'm kind of wondering if hwmod should even touch a device if it's marked >> as disabled in the DT. Tony, what do you think? > > Well nothing happens if a device is status = "disabled". No dev entry > gets created for it at all and hwmod won't have any data for the device > populated. The only way hwmod code could see that device if the device > gets it's data from the legacy omap_hwmod_*_data.c instead of DT. > We still need this for the sysconfig programming, correct? hwmod programs that regardless of dt status and then idles the IP, which is why I needed the ti,no-init for the epos evm. It isn't just a matter of we shouldnt write to it because we don't want to use it; we can't write to it because the module is held off so it causes an external abort if we do. Regards, Dave > So maybe the comments in the $subject patch are incorrect for that? > > What we really should have is also status = "incomplete" where the > dev entry gets created, but the driver never probes. This would be for > devices that are still there within the SoC, but not pinned out for > the board in question. > > We still may need also ti,no-init too for devices that we don't want > hwmod to do anything with, for example in secure mode if some blocks > are not available to Linux at all. I believe that's what's going on with > n900 crypto accelerators for example. > > Regards, > > Tony > -- 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
