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. -- Kenneth Westfield 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
