[PATCH v3 0/6] Introduce Bandwidth OPPs for interconnect paths

Saravana Kannan
2019-07-03T01:10:28Z

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 the OPP framework and in DT. Since there can
be more than one interconnect path used by a device, we also need a way to
assign a bandwidth OPP table to an interconnect path.

This patch series:
- Adds opp-peak-KBps and opp-avg-KBps properties to OPP DT bindings
- Adds interconnect-opp-table property to interconnect DT bindings
- Adds OPP helper functions for bandwidth OPP tables
- Adds icc_get_opp_table() to get the OPP table for an interconnect path

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 = <3000>;
opp-avg-KBps = <1000>;
};
gpu_cache_6000: opp-6000 {
opp-peak-KBps = <6000>;
opp-avg-KBps = <2000>;
};
gpu_cache_9000: opp-9000 {
opp-peak-KBps = <9000>;
opp-avg-KBps = <9000>;
};
};

gpu_ddr_opp_table: gpu_ddr_opp_table {
compatible = "operating-points-v2";

gpu_ddr_1525: opp-1525 {
opp-peak-KBps = <1525>;
opp-avg-KBps = <452>;
};
gpu_ddr_3051: opp-3051 {
opp-peak-KBps = <3051>;
opp-avg-KBps = <915>;
};
gpu_ddr_7500: opp-7500 {
opp-peak-KBps = <7500>;
opp-avg-KBps = <3000>;
};
};

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>;
interconnects = <&mmnoc MASTER_GPU_1 &bimc SLAVE_SYSTEM_CACHE>,
<&mmnoc MASTER_GPU_1 &bimc SLAVE_DDR>;
interconnect-names = "gpu-cache", "gpu-mem";
interconnect-opp-table = <&gpu_cache_opp_table>, <&gpu_ddr_opp_table>
};

Cheers,
Saravana

Saravana Kannan (6):
dt-bindings: opp: Introduce opp-peak-KBps and opp-avg-KBps bindings
OPP: Add support for bandwidth OPP tables
OPP: Add helper function for bandwidth OPP tables
OPP: Add API to find an OPP table from its DT node
dt-bindings: interconnect: Add interconnect-opp-table property
interconnect: Add OPP table support for interconnects

.../bindings/interconnect/interconnect.txt | 8 ++
Documentation/devicetree/bindings/opp/opp.txt | 15 +++-
drivers/interconnect/core.c | 27 ++++++-
drivers/opp/core.c | 51 +++++++++++++
drivers/opp/of.c | 76 ++++++++++++++++---
drivers/opp/opp.h | 4 +-
include/linux/interconnect.h | 7 ++
include/linux/pm_opp.h | 26 +++++++
8 files changed, 199 insertions(+), 15 deletions(-)

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2.22.0.410.gd8fdbe21b5-goog