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Thu, 23 Aug 2018 06:00:19 -0700 (PDT) From: Georgi Djakov Subject: Re: [PATCH v3 2/2] PM / devfreq: Add devfreq driver for interconnect bandwidth voting To: Saravana Kannan Cc: MyungJoo Ham , Kyungmin Park , Chanwoo Choi , Rob Herring , Mark Rutland , vincent.guittot@linaro.org, daidavid1@codeaurora.org, bjorn.andersson@linaro.org, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <1533171465-25508-2-git-send-email-skannan@codeaurora.org> Openpgp: preference=signencrypt Autocrypt: addr=georgi.djakov@linaro.org; prefer-encrypt=mutual; keydata= xsFNBFjTuRcBEACyAOVzghvyN19Sa/Nit4LPBWkICi5W20p6bwiZvdjhtuh50H5q4ktyxJtp 1+s8dMSa/j58hAWhrc2SNL3fttOCo+MM1bQWwe8uMBQJP4swgXf5ZUYkSssQlXxGKqBSbWLB uFHOOBTzaQBaNgsdXo+mQ1h8UCgM0zQOmbs2ort8aHnH2i65oLs5/Xgv/Qivde/FcFtvEFaL 0TZ7odM67u+M32VetH5nBVPESmnEDjRBPw/DOPhFBPXtal53ZFiiRr6Bm1qKVu3dOEYXHHDt nF13gB+vBZ6x5pjl02NUEucSHQiuCc2Aaavo6xnuBc3lnd4z/xk6GLBqFP3P/eJ56eJv4d0B 0LLgQ7c1T3fU4/5NDRRCnyk6HJ5+HSxD4KVuluj0jnXW4CKzFkKaTxOp7jE6ZD/9Sh74DM8v etN8uwDjtYsM07I3Szlh/I+iThxe/4zVtUQsvgXjwuoOOBWWc4m4KKg+W4zm8bSCqrd1DUgL f67WiEZgvN7tPXEzi84zT1PiUOM98dOnmREIamSpKOKFereIrKX2IcnZn8jyycE12zMkk+Sc ASMfXhfywB0tXRNmzsywdxQFcJ6jblPNxscnGMh2VlY2rezmqJdcK4G4Lprkc0jOHotV/6oJ mj9h95Ouvbq5TDHx+ERn8uytPygDBR67kNHs18LkvrEex/Z1cQARAQABzShHZW9yZ2kgRGph a292IDxnZW9yZ2kuZGpha292QGxpbmFyby5vcmc+wsF+BBMBAgAoBQJY07kXAhsDBQkHhM4A BgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRCyi/eZcnWWUuvsD/4miikUeAO6fU2Xy3fT l7RUCeb2Uuh1/nxYoE1vtXcow6SyAvIVTD32kHXucJJfYy2zFzptWpvD6Sa0Sc58qe4iLY4j M54ugOYK7XeRKkQHFqqR2T3g/toVG1BOLS2atooXEU+8OFbpLkBXbIdItqJ1M1SEw8YgKmmr JlLAaKMq3hMb5bDQx9erq7PqEKOB/Va0nNu17IL58q+Q5Om7S1x54Oj6LiG/9kNOxQTklOQZ t61oW1Ewjbl325fW0/Lk0QzmfLCrmGXXiedFEMRLCJbVImXVKdIt/Ubk6SAAUrA5dFVNBzm2 L8r+HxJcfDeEpdOZJzuwRyFnH96u1Xz+7X2V26zMU6Wl2+lhvr2Tj7spxjppR+nuFiybQq7k MIwyEF0mb75RLhW33sdGStCZ/nBsXIGAUS7OBj+a5fm47vQKv6ekg60oRTHWysFSJm1mlRyq exhI6GwUo5GM/vE36rIPSJFRRgkt6nynoba/1c4VXxfhok2rkP0x3CApJ5RimbvITTnINY0o CU6f1ng1I0A1UTi2YcLjFq/gmCdOHExT4huywfu1DDf0p1xDyPA1FJaii/gJ32bBP3zK53hM dj5S7miqN7F6ZpvGSGXgahQzkGyYpBR5pda0m0k8drV2IQn+0W8Qwh4XZ6/YdfI81+xyFlXc CJjljqsMCJW6PdgEH87BTQRY07kXARAAvupGd4Jdd8zRRiF+jMpv6ZGz8L55Di1fl1YRth6m lIxYTLwGf0/p0oDLIRldKswena3fbWh5bbTMkJmRiOQ/hffhPSNSyyh+WQeLY2kzl6geiHxD zbw37e2hd3rWAEfVFEXOLnmenaUeJFyhA3Wd8OLdRMuoV+RaLhNfeHctiEn1YGy2gLCq4VNb 4Wj5hEzABGO7+LZ14hdw3hJIEGKtQC65Jh/vTayGD+qdwedhINnIqslk9tCQ33a+jPrCjXLW X29rcgqigzsLHH7iVHWA9R5Aq7pCy5hSFsl4NBn1uV6UHlyOBUuiHBDVwTIAUnZ4S8EQiwgv WQxEkXEWLM850V+G6R593yZndTr3yydPgYv0xEDACd6GcNLR/x8mawmHKzNmnRJoOh6Rkfw2 fSiVGesGo83+iYq0NZASrXHAjWgtZXO1YwjW9gCQ2jYu9RGuQM8zIPY1VDpQ6wJtjO/KaOLm NehSR2R6tgBJK7XD9it79LdbPKDKoFSqxaAvXwWgXBj0Oz+Y0BqfClnAbxx3kYlSwfPHDFYc R/ppSgnbR5j0Rjz/N6Lua3S42MDhQGoTlVkgAi1btbdV3qpFE6jglJsJUDlqnEnwf03EgjdJ 6KEh0z57lyVcy5F/EUKfTAMZweBnkPo+BF2LBYn3Qd+CS6haZAWaG7vzVJu4W/mPQzsAEQEA AcLBZQQYAQIADwUCWNO5FwIbDAUJB4TOAAAKCRCyi/eZcnWWUhlHD/0VE/2x6lKh2FGP+QHH UTKmiiwtMurYKJsSJlQx0T+j/1f+zYkY3MDX+gXa0d0xb4eFv8WNlEjkcpSPFr+pQ7CiAI33 99kAVMQEip/MwoTYvM9NXSMTpyRJ/asnLeqa0WU6l6Z9mQ41lLzPFBAJ21/ddT4xeBDv0dxM GqaH2C6bSnJkhSfSja9OxBe+F6LIAZgCFzlogbmSWmUdLBg+sh3K6aiBDAdZPUMvGHzHK3fj gHK4GqGCFK76bFrHQYgiBOrcR4GDklj4Gk9osIfdXIAkBvRGw8zg1zzUYwMYk+A6v40gBn00 OOB13qJe9zyKpReWMAhg7BYPBKIm/qSr82aIQc4+FlDX2Ot6T/4tGUDr9MAHaBKFtVyIqXBO xOf0vQEokkUGRKWBE0uA3zFVRfLiT6NUjDQ0vdphTnsdA7h01MliZLQ2lLL2Mt5lsqU+6sup Tfql1omgEpjnFsPsyFebzcKGbdEr6vySGa3Cof+miX06hQXKe99a5+eHNhtZJcMAIO89wZmj 7ayYJIXFqjl/X0KBcCbiAl4vbdBw1bqFnO4zd1lMXKVoa29UHqby4MPbQhjWNVv9kqp8A39+ E9xw890l1xdERkjVKX6IEJu2hf7X3MMl9tOjBK6MvdOUxvh1bNNmXh7OlBL1MpJYY/ydIm3B KEmKjLDvB0pePJkdTw== Message-ID: <4fcac639-cba9-1a71-9b78-326ebb9242da@linaro.org> Date: Thu, 23 Aug 2018 16:00:18 +0300 MIME-Version: 1.0 In-Reply-To: <1533171465-25508-2-git-send-email-skannan@codeaurora.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Saravana, On 08/02/2018 03:57 AM, Saravana Kannan wrote: > This driver registers itself as a devfreq device that allows devfreq > governors to make bandwidth votes for an interconnect path. This allows > applying various policies for different interconnect paths using devfreq > governors. > > Example uses: > * Use the devfreq performance governor to set the CPU to DDR interconnect > path for maximum performance. > * Use the devfreq performance governor to set the GPU to DDR interconnect > path for maximum performance. > * Use the CPU frequency to device frequency mapping governor to scale the > DDR frequency based on the needs of the CPUs' current frequency. Usually CPUs and GPUs have dedicated cpufreq/devfreq drivers and i was wondering if the interconnect support could be put into these drivers directly? > > Signed-off-by: Saravana Kannan > --- > Documentation/devicetree/bindings/devfreq/icbw.txt | 21 ++++ > drivers/devfreq/Kconfig | 13 +++ > drivers/devfreq/Makefile | 1 + > drivers/devfreq/devfreq_icbw.c | 116 +++++++++++++++++++++ > 4 files changed, 151 insertions(+) > create mode 100644 Documentation/devicetree/bindings/devfreq/icbw.txt > create mode 100644 drivers/devfreq/devfreq_icbw.c > > diff --git a/Documentation/devicetree/bindings/devfreq/icbw.txt b/Documentation/devicetree/bindings/devfreq/icbw.txt > new file mode 100644 > index 0000000..36cf045 > --- /dev/null > +++ b/Documentation/devicetree/bindings/devfreq/icbw.txt > @@ -0,0 +1,21 @@ > +Interconnect bandwidth device > + > +icbw is a device that represents an interconnect path that connects two > +devices. This device is typically used to vote for BW requirements between > +two devices. Eg: CPU to DDR, GPU to DDR, etc > + > +Required properties: > +- compatible: Must be "devfreq-icbw" > +- interconnects: Pairs of phandles and interconnect provider specifier > + to denote the edge source and destination ports of > + the interconnect path. See also: > + Documentation/devicetree/bindings/interconnect/interconnect.txt > +- interconnect-names: Must have one entry with the name "path". > + > +Example: > + > + qcom,cpubw { > + compatible = "devfreq-icbw"; > + interconnects = <&snoc MASTER_APSS_1 &bimc SLAVE_EBI_CH0>; > + interconnect-names = "path"; interconnect-names is optional when there is only a single path. > + }; > diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig > index 3d9ae68..590370e 100644 > --- a/drivers/devfreq/Kconfig > +++ b/drivers/devfreq/Kconfig > @@ -121,6 +121,19 @@ config ARM_RK3399_DMC_DEVFREQ > It sets the frequency for the memory controller and reads the usage counts > from hardware. > > +config DEVFREQ_ICBW > + bool "DEVFREQ device for making bandwidth votes on interconnect paths" Can this be a module? > + select DEVFREQ_GOV_PERFORMANCE > + select DEVFREQ_GOV_POWERSAVE > + select DEVFREQ_GOV_USERSPACE > + default n There's no need to specify this default. It is 'n' by default anyway. Also maybe you want to add something like: depends on INTERCONNECT=y Thanks, Georgi > + help > + Different devfreq governors use this devfreq device to make > + bandwidth votes for interconnect paths between different devices > + (Eg: CPU to DDR, GPU to DDR, etc). This driver provides a generic > + interface so that the devfreq governors can be shared across SoCs > + and architectures. > + > source "drivers/devfreq/event/Kconfig"