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{ "id": 811694, "url": "http://patchwork.ozlabs.org/api/covers/811694/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-imx/cover/20170908171830.13813-1-georgi.djakov@linaro.org/", "project": { "id": 19, "url": "http://patchwork.ozlabs.org/api/projects/19/?format=api", "name": "Linux IMX development", "link_name": "linux-imx", "list_id": "linux-imx-kernel.lists.patchwork.ozlabs.org", "list_email": "linux-imx-kernel@lists.patchwork.ozlabs.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20170908171830.13813-1-georgi.djakov@linaro.org>", "list_archive_url": null, "date": "2017-09-08T17:18:27", "name": "[v3,0/3] Introduce on-chip interconnect API", "submitter": { "id": 70295, "url": "http://patchwork.ozlabs.org/api/people/70295/?format=api", "name": "Georgi Djakov", "email": "georgi.djakov@linaro.org" }, "mbox": "http://patchwork.ozlabs.org/project/linux-imx/cover/20170908171830.13813-1-georgi.djakov@linaro.org/mbox/", "series": [ { "id": 2254, "url": "http://patchwork.ozlabs.org/api/series/2254/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-imx/list/?series=2254", "date": "2017-09-08T17:18:27", "name": "Introduce on-chip interconnect API", "version": 3, "mbox": "http://patchwork.ozlabs.org/series/2254/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/811694/comments/", "headers": { "Return-Path": "<linux-arm-kernel-bounces+incoming-imx=patchwork.ozlabs.org@lists.infradead.org>", "X-Original-To": "incoming-imx@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming-imx@bilbo.ozlabs.org", "Authentication-Results": [ "ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=lists.infradead.org\n\t(client-ip=65.50.211.133; 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charset=\"us-ascii\"", "Content-Transfer-Encoding": "7bit", "Sender": "\"linux-arm-kernel\" <linux-arm-kernel-bounces@lists.infradead.org>", "Errors-To": "linux-arm-kernel-bounces+incoming-imx=patchwork.ozlabs.org@lists.infradead.org", "List-Id": "linux-imx-kernel.lists.patchwork.ozlabs.org" }, "content": "Modern SoCs have multiple processors and various dedicated cores (video, gpu,\ngraphics, modem). These cores are talking to each other and can generate a lot\nof data flowing through the on-chip interconnects. These interconnect buses\ncould form different topologies such as crossbar, point to point buses,\nhierarchical buses or use the network-on-chip concept.\n\nThese buses have been sized usually to handle use cases with high data\nthroughput but it is not necessary all the time and consume a lot of power.\nFurthermore, the priority between masters can vary depending on the running\nuse case like video playback or cpu intensive tasks.\n\nHaving an API to control the requirement of the system in term of bandwidth\nand QoS, so we can adapt the interconnect configuration to match those by\nscaling the frequencies, setting link priority and tuning QoS parameters.\nThis configuration can be a static, one-time operation done at boot for some\nplatforms or a dynamic set of operations that happen at run-time.\n\nThis patchset introduce a new API to get the requirement and configure the\ninterconnect buses across the entire chipset to fit with the current demand.\nThe API is NOT for changing the performance of the endpoint devices, but only\nthe interconnect path in between them.\n\nThe API is using a consumer/provider-based model, where the providers are\nthe interconnect buses and the consumers could be various drivers.\nThe consumers request interconnect resources (path) to an endpoint and set\nthe desired constraints on this data flow path. The provider(s) receive\nrequests from consumers and aggregate these requests for all master-slave\npairs on that path. Then the providers configure each participating in the\ntopology node according to the requested data flow path, physical links and\nconstraints. The topology could be complicated and multi-tiered and is SoC\nspecific.\n\nBelow is a simplified diagram of a real-world SoC topology. The interconnect\nproviders are the NoCs.\n\n +----------------+ +----------------+\n | HW Accelerator |--->| M NoC |<---------------+\n +----------------+ +----------------+ |\n | | +------------+\n +-----+ +-------------+ V +------+ | |\n | DDR | | +--------+ | PCIe | | |\n +-----+ | | Slaves | +------+ | |\n ^ ^ | +--------+ | | C NoC |\n | | V V | |\n +------------------+ +------------------------+ | | +-----+\n | |-->| |-->| |-->| CPU |\n | |-->| |<--| | +-----+\n | Mem NoC | | S NoC | +------------+\n | |<--| |---------+ |\n | |<--| |<------+ | | +--------+\n +------------------+ +------------------------+ | | +-->| Slaves |\n ^ ^ ^ ^ ^ | | +--------+\n | | | | | | V\n +------+ | +-----+ +-----+ +---------+ +----------------+ +--------+\n | CPUs | | | GPU | | DSP | | Masters |-->| P NoC |-->| Slaves |\n +------+ | +-----+ +-----+ +---------+ +----------------+ +--------+\n |\n +-------+ \n | Modem |\n +-------+\n\nThis patchset does not implement all features but only main skeleton to check\nthe validity of the proposal.\n\nTODO:\n * Constraints are currently stored in internal data structure. Should PM QoS\n be used instead?\n * Extend interconect_set() to handle parameters such as latency and other QoS\n values.\n * Cache the path between the nodes instead of walking the graph on each get().\n * Sync interconnect requests with the idle state of the device.\n * Replace dev_id string names resource lookups with integer ids.\n\nSummary of the patches:\nPatch 1 introduces the interconnect API.\nPatch 2 add basic support for tracepoints\nPatch 3 creates the first vendor specific interconnect bus driver.\n\nChanges since patchset v2 (https://lkml.org/lkml/2017/7/20/825)\n* Split the aggregation into per node and per provider. Cache the\n aggregated values.\n* Various small refactorings and cleanups in the framework.\n* Added a patch introducing basic tracepoint support for monitoring\n the time required to update the interconnect nodes.\n\nChanges since patchset v1 (https://lkml.org/lkml/2017/6/27/890)\n* Updates in the documentation.\n* Changes in request aggregation, locking.\n* Dropped the aggregate() callback and use the default as it currently\n sufficient for the single vendor driver. Will add it later when needed.\n* Dropped the dt-bindings draft patch for now.\n\nChanges since RFC v2 (https://lkml.org/lkml/2017/6/12/316)\n* Converted documentation to rst format.\n* Fixed an incorrect call to mutex_lock. Renamed max_bw to peak_bw.\n\nChanges since RFC v1 (https://lkml.org/lkml/2017/5/15/605)\n* Refactored code into shorter functions.\n* Added a new aggregate() API function.\n* Rearranged some structs to reduce padding bytes.\n\nChanges since RFC v0 (https://lkml.org/lkml/2017/3/1/599)\n* Removed DT support and added optional Patch 3 with new bindings proposal.\n* Converted the topology into internal driver data.\n* Made the framework modular.\n* interconnect_get() now takes (src and dst ports as arguments).\n* Removed public declarations of some structs.\n* Now passing prev/next nodes to the vendor driver.\n* Properly remove requests on _put().\n* Added refcounting.\n* Updated documentation.\n* Changed struct interconnect_path to use array instead of linked list.\n\n\nGeorgi Djakov (3):\n interconnect: Add generic on-chip interconnect API\n interconnect: Add basic event tracing\n interconnect: Add Qualcomm msm8916 interconnect provider driver\n\n Documentation/interconnect/interconnect.rst | 93 ++++++\n drivers/Kconfig | 2 +\n drivers/Makefile | 1 +\n drivers/interconnect/Kconfig | 15 +\n drivers/interconnect/Makefile | 2 +\n drivers/interconnect/interconnect.c | 389 +++++++++++++++++++++++\n drivers/interconnect/qcom/Kconfig | 11 +\n drivers/interconnect/qcom/Makefile | 1 +\n drivers/interconnect/qcom/interconnect_msm8916.c | 375 ++++++++++++++++++++++\n include/linux/interconnect-consumer.h | 73 +++++\n include/linux/interconnect-provider.h | 119 +++++++\n include/linux/interconnect/qcom-msm8916.h | 92 ++++++\n include/trace/events/interconnect.h | 45 +++\n 13 files changed, 1218 insertions(+)\n create mode 100644 Documentation/interconnect/interconnect.rst\n create mode 100644 drivers/interconnect/Kconfig\n create mode 100644 drivers/interconnect/Makefile\n create mode 100644 drivers/interconnect/interconnect.c\n create mode 100644 drivers/interconnect/qcom/Kconfig\n create mode 100644 drivers/interconnect/qcom/Makefile\n create mode 100644 drivers/interconnect/qcom/interconnect_msm8916.c\n create mode 100644 include/linux/interconnect-consumer.h\n create mode 100644 include/linux/interconnect-provider.h\n create mode 100644 include/linux/interconnect/qcom-msm8916.h\n create mode 100644 include/trace/events/interconnect.h" }