| Message ID | 20170612141359.26117-1-georgi.djakov@linaro.org |
|---|---|
| Headers | show |
| Series | Introduce on-chip interconnect API | expand |
On 06/13/2017 04:42 PM, Greg KH wrote: > On Mon, Jun 12, 2017 at 05:13:57PM +0300, Georgi Djakov wrote: >> This patch introduce a new API to get the requirement and configure the >> interconnect buses across the entire chipset to fit with the current demand. >> >> The API is using a consumer/provider-based model, where the providers are >> the interconnect controllers and the consumers could be various drivers. >> The consumers request interconnect resources (path) to an endpoint and set >> the desired constraints on this data flow path. The provider(s) receive >> requests from consumers and aggregate these requests for all master-slave >> pairs on that path. Then the providers configure each participating in the >> topology node according to the requested data flow path, physical links and >> constraints. The topology could be complicated and multi-tiered and is SoC >> specific. >> >> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org> >> --- >> Documentation/interconnect/interconnect.txt | 65 +++++ >> drivers/Kconfig | 2 + >> drivers/Makefile | 1 + >> drivers/interconnect/Kconfig | 10 + >> drivers/interconnect/Makefile | 1 + >> drivers/interconnect/interconnect.c | 376 ++++++++++++++++++++++++++++ >> include/linux/interconnect-consumer.h | 72 ++++++ >> include/linux/interconnect-provider.h | 120 +++++++++ >> 8 files changed, 647 insertions(+) >> create mode 100644 Documentation/interconnect/interconnect.txt >> create mode 100644 drivers/interconnect/Kconfig >> create mode 100644 drivers/interconnect/Makefile >> create mode 100644 drivers/interconnect/interconnect.c >> create mode 100644 include/linux/interconnect-consumer.h >> create mode 100644 include/linux/interconnect-provider.h >> >> diff --git a/Documentation/interconnect/interconnect.txt b/Documentation/interconnect/interconnect.txt >> new file mode 100644 >> index 000000000000..f761a2fb553c >> --- /dev/null >> +++ b/Documentation/interconnect/interconnect.txt > > .rst for new Documenation files please, and hook it up to the larger > documentation build process at the same time. Ah right, will convert it to rst! > > And why are these RFC patches? Don't you feel they are ready to be > reviewed? I know I ignore RFC patches for the most part as obviously > the author does not think they are ready :) I'm trying to raise a discussion around this topic and get more comments whether this is moving into the right direction and are there any big concerns left. Its RFC because its not ready to be applied yet, but sure i will make it a "patch" next time. Reviewing is very welcome! Thanks, Georgi
Modern SoCs have multiple processors and various dedicated cores (video, gpu, graphics, modem). These cores are talking to each other and can generate a lot of data flowing through the on-chip interconnects. These interconnect buses could form different topologies such as crossbar, point to point buses, hierarchical buses or use the network-on-chip concept. These buses have been sized usually to handle use cases with high data throughput but it is not necessary all the time and consume a lot of power. Furthermore, the priority between masters can vary depending on the running use case like video playback or cpu intensive tasks. Having an API to control the requirement of the system in term of bandwidth and QoS, so we can adapt the interconnect configuration to match those by scaling the frequencies, setting link priority and tuning QoS parameters. This configuration can be a static, one-time operation done at boot for some platforms or a dynamic set of operations that happen at run-time. This patchset introduce a new API to get the requirement and configure the interconnect buses across the entire chipset to fit with the current demand. The API is NOT for changing the performance of the endpoint devices, but only the interconnect path in between them. The API is using a consumer/provider-based model, where the providers are the interconnect controllers and the consumers could be various drivers. The consumers request interconnect resources (path) to an endpoint and set the desired constraints on this data flow path. The provider(s) receive requests from consumers and aggregate these requests for all master-slave pairs on that path. Then the providers configure each participating in the topology node according to the requested data flow path, physical links and constraints. The topology could be complicated and multi-tiered and is SoC specific. Below is a simplified diagram of a real-world SoC topology. The interconnect providers are the memory front-end and the NoCs. +----------------+ +----------------+ | HW Accelerator |--->| M NoC |<---------------+ +----------------+ +----------------+ | | | +------------+ +-------------+ V +------+ | | | +--------+ | PCIe | | | | | Slaves | +------+ | | | +--------+ | | C NoC | V V | | +------------------+ +------------------------+ | | +-----+ | |-->| |-->| |-->| CPU | | |-->| |<--| | +-----+ | Memory | | S NoC | +------------+ | |<--| |---------+ | | |<--| |<------+ | | +--------+ +------------------+ +------------------------+ | | +-->| Slaves | ^ ^ ^ ^ | | +--------+ | | | | | V +-----+ | +-----+ +-----+ +---------+ +----------------+ +--------+ | CPU | | | GPU | | DSP | | Masters |-->| P NoC |-->| Slaves | +-----+ | +-----+ +-----+ +---------+ +----------------+ +--------+ | +-------+ | Modem | +-------+ This RFC does not implement all features but only main skeleton to check the validity of the proposal. TODO: * Constraints are currently stored in internal data structure. Should PM QoS be used instead? * Extend interconect_set() to handle parameters such as latency and other QoS values. * Cache the path between the nodes instead of walking the graph on each get(). * Sync interconnect requests with the idle state of the device. Summary of the patches: Patch 1 introduces the interconnect API. Patch 2 creates the first vendor specific interconnect controller driver. Patch 3 is a proposal for DT bindings Changes since RFC v1 (https://lkml.org/lkml/2017/5/15/605) * Refactored code into shorter functions. * Added a new aggregate() API function. * Rearranged some structs to reduce padding bytes. Changes since RFC v0 (https://lkml.org/lkml/2017/3/1/599) * Removed DT support and added optional Patch 3 with new bindings proposal. * Converted the topology into internal driver data. * Made the framework modular. * interconnect_get() now takes (src and dst ports as arguments). * Removed public declarations of some structs. * Now passing prev/next nodes to the vendor driver. * Properly remove requests on _put(). * Added refcounting. * Updated documentation. * Changed struct interconnect_path to use array instead of linked list. Georgi Djakov (3): interconnect: Add generic interconnect controller API interconnect: Add Qualcomm msm8916 interconnect provider driver dt-binding: Interconnect device-tree bindings draft .../bindings/interconnect/interconnect.txt | 75 ++++ Documentation/interconnect/interconnect.txt | 65 ++++ drivers/Kconfig | 2 + drivers/Makefile | 1 + drivers/interconnect/Kconfig | 15 + drivers/interconnect/Makefile | 2 + drivers/interconnect/interconnect.c | 376 +++++++++++++++++++ drivers/interconnect/qcom/Kconfig | 12 + drivers/interconnect/qcom/Makefile | 2 + drivers/interconnect/qcom/interconnect_msm8916.c | 417 +++++++++++++++++++++ include/dt-bindings/interconnect/qcom,msm8916.h | 87 +++++ include/linux/interconnect-consumer.h | 72 ++++ include/linux/interconnect-provider.h | 120 ++++++ 13 files changed, 1246 insertions(+) create mode 100644 Documentation/devicetree/bindings/interconnect/interconnect.txt create mode 100644 Documentation/interconnect/interconnect.txt create mode 100644 drivers/interconnect/Kconfig create mode 100644 drivers/interconnect/Makefile create mode 100644 drivers/interconnect/interconnect.c create mode 100644 drivers/interconnect/qcom/Kconfig create mode 100644 drivers/interconnect/qcom/Makefile create mode 100644 drivers/interconnect/qcom/interconnect_msm8916.c create mode 100644 include/dt-bindings/interconnect/qcom,msm8916.h create mode 100644 include/linux/interconnect-consumer.h create mode 100644 include/linux/interconnect-provider.h