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Mon, 6 Jan 2020 10:31:22 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20200106013122epsmtip1d1087755a7ebce07ebc8ba09f1acd44f~nKBkfaiSH1136211362epsmtip1c; Mon, 6 Jan 2020 01:31:22 +0000 (GMT) Subject: Re: [PATCH 4/9] PM / devfreq: exynos-bus: Replace deprecated 'devfreq' property From: Chanwoo Choi To: Rob Herring Cc: krzk@kernel.org, mark.rutland@arm.com, heiko@sntech.de, leonard.crestez@nxp.com, lukasz.luba@arm.com, a.swigon@samsung.com, m.szyprowski@samsung.com, kgene@kernel.org, myungjoo.ham@samsung.com, kyungmin.park@samsung.com, linux-pm@vger.kernel.org, linux-samsung-soc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org Organization: Samsung Electronics Message-ID: <76616499-7c19-06b1-461a-28ae17a76c60@samsung.com> Date: Mon, 6 Jan 2020 10:38:29 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Thunderbird/59.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrPJsWRmVeSWpSXmKPExsWy7bCmge7rXqE4g6cf1Szuz2tltJh/5Byr xf9Hr1kt+h+/ZrY4f34Du8XZpjfsFivufmS12PT4GqvF5V1z2Cw+9x5htPj04D+zxYzz+5gs Fja1sFusPXKX3WLp9YtMFrcbV7BZ/N+zg91B0GPNvDWMHptWdbJ5bF5S77Hx3Q4mj74tqxg9 tl+bx+zxeZNcAHtUtk1GamJKapFCal5yfkpmXrqtkndwvHO8qZmBoa6hpYW5kkJeYm6qrZKL T4CuW2YO0AdKCmWJOaVAoYDE4mIlfTubovzSklSFjPziElul1IKUnALLAr3ixNzi0rx0veT8 XCtDAwMjU6DChOyMl3+vMBacEqtoWdzC1sC4SKiLkZNDQsBE4uTixcwgtpDADkaJ/4vCuxi5 gOxPjBKPp/9jhXC+MUq8+t/HBtMxrXk6C0RiL6PE7fO/2SCc94wSm5beYgWpEhaIkth2YBGY zSagJbH/xQ2wbhEBRYnfbdPAxjILrGGWaJvymwUkwQ+UuPrjMSOIzStgJ7F1/xmgIg4OFgEV idvNFSBhUYEwiZPbWqBKBCVOznzCAlLCKWAvceWUPUiYWUBc4taT+UwQtrzE9rdzmEFWSQic YpeYdnITE8QHLhIt++ZBfSMs8er4FnYIW0riZX8blF0tsfLkETaI5g5GiS37L7BCJIwl9i+d zASymFlAU2L9Ln2IsKLEzt9zGSEW80m8+9oDdr6EAK9ERxs0qJUlLj+4C3WCpMTi9k62CYxK s5B8MwvJC7OQvDALYdkCRpZVjGKpBcW56anFhgVGyJG9iRGcuLXMdjAuOudziFGAg1GJh5ch WChOiDWxrLgy9xCjBAezkghvo5tgnBBvSmJlVWpRfnxRaU5q8SFGU2BYT2SWEk3OB2aVvJJ4 Q1MjY2NjCxNDM1NDQyVxXo4fF2OFBNITS1KzU1MLUotg+pg4OKUaGFXm7eLaacTF9XOK68Lr +Xonv0Q8Wfp6rcZW4euJuQbMZlon2qtkfVfqbT3wM/xmeMHE+OjZry+nR39zTfiv+ObgrvRX z3WsDbZnWDVaxW5ebdi5f+F5qz2ePwL+bq3bzfBeu/X2hwf7gxeKvlm43n6tRnhUM4ONlzJ7 PkcYC3PG1HyFE9PidymxFGckGmoxFxUnAgCG0r0r8gMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrJIsWRmVeSWpSXmKPExsWy7bCSnO6rXqE4g7edNhb357UyWsw/co7V 4v+j16wW/Y9fM1ucP7+B3eJs0xt2ixV3P7JabHp8jdXi8q45bBafe48wWnx68J/ZYsb5fUwW C5ta2C3WHrnLbrH0+kUmi9uNK9gs/u/Zwe4g6LFm3hpGj02rOtk8Ni+p99j4bgeTR9+WVYwe 26/NY/b4vEkugD2KyyYlNSezLLVI3y6BK+Pl3yuMBafEKloWt7A1MC4S6mLk5JAQMJGY1jyd pYuRi0NIYDejRO/Kn0wQCUmJaRePMncxcgDZwhKHDxeDhIUE3jJK/G8PBLGFBaIkth1YxApi swloSex/cYMNxBYRUJT43TaNFWQms8AaZonzPd1QCyYxSax8sxGsih+o6uqPx4wgNq+AncTW /WdYQZaxCKhI3G6uAAmLCoRJ7FzymAmiRFDi5MwnLCAlnAL2EldO2YOEmQXUJf7Mu8QMYYtL 3HoynwnClpfY/nYO8wRG4VlIumchaZmFpGUWkpYFjCyrGCVTC4pz03OLDQsM81LL9YoTc4tL 89L1kvNzNzGCI1hLcwfj5SXxhxgFOBiVeHhXBAjFCbEmlhVX5h5ilOBgVhLhbXQTjBPiTUms rEotyo8vKs1JLT7EKM3BoiTO+zTvWKSQQHpiSWp2ampBahFMlomDU6qBUavr0C3B4Cn8z4zv Nd+p0fP4fuhobP/17esrHpvwHk+ZPJPVevKKd5oN2reCPDUfzOdvapjLKdlcvTJV4BFba03k BRun6aKfbI0+mgWbfWZ4a5v2uzyaeTPbX8fIg/89a132rm5cn+B2xcLpcprVYsdq35x0XkbJ QE6m3Q9vRU8VqdnzO3uLEktxRqKhFnNRcSIAgoO6E9wCAAA= X-CMS-MailID: 20200106013123epcas1p49edbebd5bf248f8814d56240ef670218 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20191217055106epcas1p11f2bc81d6bb2db3fc4bc257d78c337b9 References: <20191217055738.28445-1-cw00.choi@samsung.com> <20191217055738.28445-5-cw00.choi@samsung.com> <20191226210119.GA8706@bogus> Sender: linux-samsung-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org Hi Rob, Gently Ping. On 12/27/19 9:09 AM, Chanwoo Choi wrote: > On 12/27/19 6:01 AM, Rob Herring wrote: >> On Tue, Dec 17, 2019 at 02:57:33PM +0900, Chanwoo Choi wrote: >>> In order to remove the deprecated 'devfreq' property, replace with >>> new 'exynos,parent-bus' property in order to get the parent devfreq device >>> in devicetree file instead of 'devfreq' property. But, to guarantee the >>> backward-compatibility, keep the support 'devfreq' property. >>> >>> Signed-off-by: Chanwoo Choi >>> --- >>> .../bindings/devfreq/exynos-bus.txt | 16 +++++++-------- >>> drivers/devfreq/exynos-bus.c | 20 ++++++++++++------- >>> 2 files changed, 21 insertions(+), 15 deletions(-) >>> >>> diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt >>> index e71f752cc18f..c948cee01124 100644 >>> --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt >>> +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt >>> @@ -45,7 +45,7 @@ Required properties only for parent bus device: >>> of buses. >>> >>> Required properties only for passive bus device: >>> -- devfreq: the parent bus device. >>> +- exynos,parent-bus: the parent bus device. >> >> If you are going to do something new, why not use the interconnect >> binding here? > > As I knew, interconnect make the data path among multiple nodes > and set the average and peak bandwidth to the specific data path. > > It means that some data will be flowed from node_a to node_d > or the reverse way because each node has the tightly coupled > dependency for data flow. > > node_a <-> node_b <-> node_c <-> node_d > > > On the other hand, exynos-bus.c driver is not related to 'data path'. > Each bus just need to control the their own frequency and voltage. > But, share the power line (regulator) between exynos-bus device > even if there are no any dependency of data flow. > > 'exynos,parent-bus' property just indicate the specific > devfreq device(parent bus device) which controls > the shared power line(regulator) in order to prevent > the h/w problem due to the wrong pair of frequency and voltage. > > 'exynos,parent-bus' property is only used to catch > the change timing of shared power line. > > > And, > as you commented, there are some data path among the exynos-bus > devices for the display h/w as following: > > bus_display -> bus_leftbus -> bus_dmc > > In order to make the data path between bus devices, > interconnect binding is required. This approach[1] was posted. > [1] https://patchwork.kernel.org/cover/11305265/ > - [RFC,v3,0/7] PM / devfreq: Simple QoS for exynos-bus using interconnect > Are there any other commentss? -- Best Regards, Chanwoo Choi Samsung Electronics