On Mar 6, 2015, at 4:03 PM, Kenneth Westfield <kwestfie@xxxxxxxxxxxxxx> wrote: > On Fri, Mar 06, 2015 at 10:07:01AM -0600, Kumar Gala wrote: >> On Mar 5, 2015, at 7:51 PM, Kenneth Westfield <kwestfie@xxxxxxxxxxxxxx> wrote: >>> On Thu, Mar 05, 2015 at 12:52:30PM -0600, Kumar Gala wrote: >>>> On Mar 3, 2015, at 6:21 PM, Kenneth Westfield <kwestfie@xxxxxxxxxxxxxx> wrote: >>>> >>>>> +++ b/Documentation/devicetree/bindings/sound/qcom,lpass-cpu.txt >>>>> @@ -0,0 +1,49 @@ >>>>> +* Qualcomm Technologies LPASS CPU DAI >>>>> + >>>>> +Required subnodes: >>>>> + >>>>> +- qcom,adsp : Audio DSP sub-node >>>>> + >>>>> +Optional Audio DSP subnode properties: >>>>> + >>>>> +- status : "disabled" indicates the adsp is not available. >>>>> + >>>> >>>> What is the intent of this subnode? >>>> >>> >>> From the cover letter: >>> Even though the ipq806x LPASS does not contain an audio DSP, other SOCs >>> do have one. For those SOCs, the audio DSP typically controls the >>> hardware blocks in the LPASS. Hence, different CPU DAI driver(s) would >>> need to be used in order to facilitate audio with the DSP. As such, the >>> LPASS DT contains an adsp subnode, which is disabled for this SOC. The >>> same subnode should be enabled and populated for other SOCs that do >>> contain an audio DSP. Not using the audio DSP would require different >>> CPU DAI driver(s), in addition to possible bootloader and/or firmware >>> changes. >>> >>> This was the result of a request from Mark. See here: >>> http://thread.gmane.org/gmane.linux.drivers.devicetree/109331/focus=11633 >> >> Two quick comments before I read Mark?s comments. >> >> 1. Its not normal practice to put something into a DT that does not exist. Having a node, but marking it disabled implies existence. > > Will change the DT definition to optional. > >> 2. How would one normally address the audio DSP if it did exist. I?m just wondering if having a subnode is the proper solution vs maybe a phandle > > The audio DSP is, in fact, contained within the audio subsystem. The > representation of that relationship in the DT, I believe, would be a subnode. > OTOH, if there is a strong sentiment towards using a phandle, that would be > fine with me. Just depends on how we communicate with the DSP. If its mostly via MMIO access than a sub node makes sense. If its via some other RPC/communication mechanism than possibly a phandle. Trying to understand a bit more to than see what I’d recommend. - k -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project -- 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
