On Tue, Oct 8, 2013 at 3:43 PM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote: > On 10/08/2013 11:33 AM, Nishanth Menon wrote: >> On 10/08/2013 12:08 PM, Stephen Warren wrote: >>> On 10/08/2013 10:14 AM, Nishanth Menon wrote: >>>> On 10/08/2013 09:39 AM, Laxman Dewangan wrote: >>>>> Thanks Nishanth for review. >>>>> >>>>> On Tuesday 08 October 2013 06:59 PM, Nishanth Menon wrote: >>>>>> On 10/08/2013 08:21 AM, Laxman Dewangan wrote: >>>>>>> Palmas devices has two clock output CLK32K_KG and CLK32K_KG_AUDIO >>>>>> not all palmas devices have 2 clocks - example: tps659038 >>>>> >>>>> This is for generic palmas and I have seen it for TPS65913, TPS65914, >>>>> TPS80036. If the generic one is not compatible then it need to add >>>>> device specific and at that time, it is require to update the binding >>>>> document accordingly. >>>> >>>> ?? you do have two clocks inside the device they should be represented >>>> as two compatible entities - that simplifies everyone's life. >>> >>> I think the terminology you're using here is quite confusing. >>> >>> Are you talking about having two different compatible values for two >>> different HW designs, where those different designs implement different >>> sets of clocks (which makes sense), or two different DT nodes for two >>> different clocks (which IMHO doesn't always, unless those different >>> clocks *truly* are separate IP blocks with completely independent >>> register regions, and where those IP blocks are likely to be re-used >>> as-is in other chips). >> >> clk32k and clk32k_audio are two different resources and since these >> are two different resource instances - a "compatible" matching an >> actual device is my suggestion. > > The fact that two clocks are two different resources isn't at all > relevant to DT structure. HW module design is what's relevant. > >> clk32k and clk32k_audio are two different resources because they have >> their specific set of controls registers and may even be independently >> present in a Palmas variant. > > That's a better argument, assuming that: The registers for those two > clocks aren't randomly interleaved with other registers within the HW > module. That would imply that the clock registers aren't independant HW > blocks. You would be unpleasantly surprised if register offsets is a standard to determine if IP blocks are independent instances or not. it is just integration level decision, and unfortunately, not all h/w integration guys care a lot about s/w :(. > >> To highlight this: The example of tps659038 where clk32k is not >> present, but clk32k_audio is present (and happens to be disabled by >> default - thanks to an OTP on the chip - on platform like DRA7-evm, it >> is used to for 32k clk for wlan -currently hacked in u-boot using >> plain i2c writes[1] - yes it is yucky). > > That can easily be handled by having separate compatible values for a > monolithic overall Palmas or Palmas-clock node/HW-block. The fact that > different chips are different doesn't, in and of itself, need to > influence whether the different clocks are represented as different DT > nodes. So, the fact that a clock does not exist on a variation of palmas is not sufficient proof that the blocks are independent. I am not sure, given the lack of public documentation, short of sharing rtl (which I cant ;) ), i might let this debate flame out.. > >> Obviously, there are many ways to implement this. based on the current >> implementation, it indicates that if i create a node with >> "ti,palmas-clk" -i'd create two clocks - that is wrong for tps659038. >> >> Now (with the current approach), if I have to create a one clock for >> tps659038, i have to fix the for adding clock providers, add up >> "ti,tps659038-clk" etc.. it is doable - but IMHO, I dont need to do it >> with only the relevant nodes in dts. >> >> Further, it has no way to indicate that device X uses clock Y using >> clocks =<&xyz> either. > > Sorry, I just don't understand that. > > If a clock provider provides two clocks, it could number then e.g. 0 and > 1. Clock consumers would reference those IDs. If a different chip that > uses the same binding only supports one of those two clocks, just have > the driver return an error if the DT attempts to use/reference the > invalid clock ID; nothign could be simpler. fair enough. Regards, Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
