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SubjectRe: [PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects
On 26-07-19, 16:15, Saravana Kannan wrote:
> Interconnects and interconnect paths quantify their performance levels in
> terms of bandwidth and not in terms of frequency. So similar to how we have
> frequency based OPP tables in DT and in the OPP framework, we need
> bandwidth OPP table support in DT and in the OPP framework.
>
> So with the DT bindings added in this patch series, the DT for a GPU
> that does bandwidth voting from GPU to Cache and GPU to DDR would look
> something like this:
>
> gpu_cache_opp_table: gpu_cache_opp_table {
> compatible = "operating-points-v2";
>
> gpu_cache_3000: opp-3000 {
> opp-peak-KBps = <3000000>;
> opp-avg-KBps = <1000000>;
> };
> gpu_cache_6000: opp-6000 {
> opp-peak-KBps = <6000000>;
> opp-avg-KBps = <2000000>;
> };
> gpu_cache_9000: opp-9000 {
> opp-peak-KBps = <9000000>;
> opp-avg-KBps = <9000000>;
> };
> };
>
> gpu_ddr_opp_table: gpu_ddr_opp_table {
> compatible = "operating-points-v2";
>
> gpu_ddr_1525: opp-1525 {
> opp-peak-KBps = <1525000>;
> opp-avg-KBps = <452000>;
> };
> gpu_ddr_3051: opp-3051 {
> opp-peak-KBps = <3051000>;
> opp-avg-KBps = <915000>;
> };
> gpu_ddr_7500: opp-7500 {
> opp-peak-KBps = <7500000>;
> opp-avg-KBps = <3000000>;
> };
> };
>
> gpu_opp_table: gpu_opp_table {
> compatible = "operating-points-v2";
> opp-shared;
>
> opp-200000000 {
> opp-hz = /bits/ 64 <200000000>;
> };
> opp-400000000 {
> opp-hz = /bits/ 64 <400000000>;
> };
> };
>
> gpu@7864000 {
> ...
> operating-points-v2 = <&gpu_opp_table>, <&gpu_cache_opp_table>, <&gpu_ddr_opp_table>;
> ...
> };

One feedback I missed giving earlier. Will it be possible to get some
user code merged along with this ? I want to make sure anything we add
ends up getting used.

That also helps understanding the problems you are facing in a better
way, i.e. with real examples.

--
viresh

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