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>;
...
};
v1 -> v3:
- Lots of patch additions that were later dropped
v3 -> v4:
- Fixed typo bugs pointed out by Sibi.
- Fixed bug that incorrectly reset rate to 0 all the time
- Added units documentation
- Dropped interconnect-opp-table property and related changes
Cheers,
Saravana
Saravana Kannan (3):
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
Documentation/devicetree/bindings/opp/opp.txt | 15 ++++--
.../devicetree/bindings/property-units.txt | 4 ++
drivers/opp/core.c | 51 +++++++++++++++++++
drivers/opp/of.c | 41 +++++++++++----
drivers/opp/opp.h | 4 +-
include/linux/pm_opp.h | 19 +++++++
6 files changed, 121 insertions(+), 13 deletions(-)
--
2.22.0.709.g102302147b-goog
