Re: [PATCH 00/53] icc-rpmh multi-RSC voting groundwork

[Mike Tipton <quic_mdtipton@quicinc.com>]

On Wed, Sep 13, 2023 at 10:31:49AM +0200, Konrad Dybcio wrote:
> > The applicable voters should likely be defined in the target-specific
> > headers, rather than the common qcom,icc.h. The bit range used for them
> > could be common, but each target may only support a small subset of the
> > total set of possible voters across all targets.
> I'm not sure how client drivers would then choose the
> correct path other than
> 
> switch (soc) {
> case 8450:
> 	tag = QCOM_ICC_TAG_VOTER_8450_HLOS;
> 	break;
> case 8550:
> 	tag = QCOM_ICC_TAG_VOTER_8550_HLOS;
> 	break;
> ...
> }
> 
> which would be unacceptable.

The same general way it's handled for the endpoint bindings, which are
already target-specific. 

Any client drivers hardcoding the endpoint bindings in their driver
would have to include the appropriate, target-specific binding header
(e.g. qcom,sm8550-rpmh.h). That would only be possible if their driver
file is itself target-specific. Otherwise, it would have to pull the
endpoint bindings from devicetree. Or just use the recommended
of_icc_get() and let devicetree do everything for them. Same for the
target-specific voter tag bindings.

Clients can also specify their tags in devicetree. They don't actually
have to call icc_set_tag() directly. For example:

    #include <dt-bindings/interconnect/qcom,sm8450.h>

    interconnects = <&mmss_noc MASTER_MDP QCOM_ICC_TAG_VOTER_DISP
                     &mc_virt SLAVE_EBI1 QCOM_ICC_TAG_VOTER_DISP>;

Then when they call of_icc_get() for this path it'll automatically have
QCOM_ICC_TAG_VOTER_DISP set for them.