>>-----Original Message----- >>From: Kevin Hilman [mailto:[email protected]] >>Sent: Thursday, September 16, 2010 8:52 PM >>To: Gopinath, Thara >>Cc: [email protected]; [email protected]; Sripathy, Vishwanath; Sawant, >>Anand; Cousson, Benoit >>Subject: Re: [PATCH 04/13] OMAP: Introduce API to return a device list >>associated with a voltage >>domain >> >>"Gopinath, Thara" <[email protected]> writes: >> >>[...] >> >>>>>> +struct device **opp_init_voltage_params(struct voltagedomain *voltdm, >>>>>> + int *dev_count) >>>>>> +{ >>>>>> + struct device_opp *dev_opp; >>>>>> + struct device **dev_list; >>>>>> + int count = 0, i = 0; >>>>>> + >>>>>> + list_for_each_entry(dev_opp, &dev_opp_list, node) { >>>>>> + if (!dev_opp->oh->vdd_name) >>>>>> + continue; >>>>>> + >>>>>> + if (!strcmp(dev_opp->oh->vdd_name, voltdm->name)) { >>>>>> + dev_opp->oh->voltdm = voltdm; >>>>> >>>>>Couldn't we assign the voltdm at opp_add() time since you added it as >>>>>part of the hwmod? >>> >>> We cannot as the voltage layer is not initialized at the point of opp_add. >>> Having said this, today voltage layer is dependent on opp layer only to >>> figure out >>> the current nominal voltage from the opp table. If that can be some how >>> decoupled we >>> can initialize voltage layer early on and implement this. >> >>We could decouple the voltage init into and early init and late init to >>handle this.
Hello Kevin, Yes we could. In fact I do not like the idea of voltage layer dependent on opp layer itself. So here is my proposal. Maintain a variable in the main per vdd structure omap_vdd_info curr_volt which will get updated each time a voltage scale is attempted. Now the only issue is during boot up how does the voltage layer know what voltage each vdd should be put into ? A piece of code can be implemented in pm34xx.c/pm44xx.c init functions to read the clock rate associated with each vdd , call into the opp layer to get the corresponding voltage ( basically the sequence we do today everytime in voltage layer when the API to get nominal voltage is called) and call omap_voltage_scale_vdd with the corresponding voltage. This way we can fully decouple voltage laye from opp layer and make voltage init an early_initcall. We might still need a late_initcall to register debugfs entries though. What is your take on this ? Regards Thara >> >>Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
