From: Chanwoo Choi <chanwoo@kernel.org>
To: Chanwoo Choi <cw00.choi@samsung.com>
Cc: "Rob Herring" <robh@kernel.org>,
"Krzysztof Kozlowski" <krzk@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Heiko Stübner" <heiko@sntech.de>,
"Leonard Crestez" <leonard.crestez@nxp.com>,
lukasz.luba@arm.com, "Artur Świgoń" <a.swigon@samsung.com>,
"Marek Szyprowski" <m.szyprowski@samsung.com>,
"Kukjin Kim" <kgene@kernel.org>,
"MyungJoo Ham" <myungjoo.ham@samsung.com>,
"Kyungmin Park" <kyungmin.park@samsung.com>,
"Linux PM list" <linux-pm@vger.kernel.org>,
linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
devicetree <devicetree@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
"open list:ARM/Rockchip SoC..."
<linux-rockchip@lists.infradead.org>
Subject: Re: [PATCH 4/9] PM / devfreq: exynos-bus: Replace deprecated 'devfreq' property
Date: Wed, 15 Jan 2020 03:57:30 +0900 [thread overview]
Message-ID: <CAGTfZH0K65ON0FQGUjQbr71_9VWJXTmRbih1gko6Pcuy+PL63Q@mail.gmail.com> (raw)
In-Reply-To: <76616499-7c19-06b1-461a-28ae17a76c60@samsung.com>
Hi Rob,
On Mon, Jan 6, 2020 at 10:32 AM Chanwoo Choi <cw00.choi@samsung.com> wrote:
>
> Hi Rob,
>
> Gently Ping.
Once again, ping. Could you please review?
On v2[1], made separate patches for dt-binding.
[1] https://patchwork.kernel.org/cover/11304545/
>
> 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 <cw00.choi@samsung.com>
> >>> ---
> >>> .../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
--
Best Regards,
Chanwoo Choi
next prev parent reply other threads:[~2020-01-14 18:58 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20191217055105epcas1p365e306f27fd53852b793155c929ee634@epcas1p3.samsung.com>
2019-12-17 5:57 ` [PATCH 0/9] PM / devfreq: Remove deprecated 'devfreq' and 'devfreq-events' properties Chanwoo Choi
[not found] ` <CGME20191217055105epcas1p3bacbf54550c52979fe819ab33bb21d30@epcas1p3.samsung.com>
2019-12-17 5:57 ` [PATCH 1/9] PM / devfreq: Add devfreq_get_devfreq_by_node function Chanwoo Choi
[not found] ` <CGME20191217055105epcas1p2d2930402a559e381a7854f515a683d15@epcas1p2.samsung.com>
2019-12-17 5:57 ` [PATCH 2/9] PM / devfreq: Remove devfreq_get_devfreq_by_phandle function Chanwoo Choi
2019-12-17 14:33 ` Leonard Crestez
2019-12-18 2:59 ` Chanwoo Choi
2019-12-18 3:20 ` Chanwoo Choi
[not found] ` <CGME20191217055106epcas1p3e77268d200006921dfa736b2c7550a04@epcas1p3.samsung.com>
2019-12-17 5:57 ` [PATCH 3/9] PM / devfreq: event: Add devfreq_event_get_edev_by_node function Chanwoo Choi
[not found] ` <CGME20191217055106epcas1p11f2bc81d6bb2db3fc4bc257d78c337b9@epcas1p1.samsung.com>
2019-12-17 5:57 ` [PATCH 4/9] PM / devfreq: exynos-bus: Replace deprecated 'devfreq' property Chanwoo Choi
2019-12-26 21:01 ` Rob Herring
2019-12-27 0:09 ` Chanwoo Choi
2020-01-06 1:38 ` Chanwoo Choi
2020-01-14 18:57 ` Chanwoo Choi [this message]
[not found] ` <CGME20191217055106epcas1p4b50ca647af9b54465e5c0a0bebb165b8@epcas1p4.samsung.com>
2019-12-17 5:57 ` [PATCH 5/9] PM / devfreq: exynos-bus: Replace deprecated 'devfreq-events' property Chanwoo Choi
[not found] ` <CGME20191217055106epcas1p156b1323f4ec9f7c35fed825d56e577ff@epcas1p1.samsung.com>
2019-12-17 5:57 ` [PATCH 6/9] PM / devfreq: rk3399_dmc: " Chanwoo Choi
[not found] ` <CGME20191217055106epcas1p2c43a45e34983c1b3e60cc6fd842dd33e@epcas1p2.samsung.com>
2019-12-17 5:57 ` [PATCH 7/9] memory: samsung: exynos5422-dmc: " Chanwoo Choi
2019-12-17 11:03 ` Lukasz Luba
2019-12-19 20:19 ` Krzysztof Kozlowski
[not found] ` <CGME20191217055106epcas1p4c0f65bec74e53b38d95e984e146bf8b6@epcas1p4.samsung.com>
2019-12-17 5:57 ` [PATCH 8/9] ARM: dts: exynos: Replace deprecated property for Exynos bus and DMC Chanwoo Choi
2019-12-19 20:21 ` Krzysztof Kozlowski
[not found] ` <CGME20191217055107epcas1p44d46bdea7b326b86689f326742f5444a@epcas1p4.samsung.com>
2019-12-17 5:57 ` [PATCH 9/9] arm64: dts: exynos: Replace deprecated property for Exynos bus Chanwoo Choi
2019-12-19 20:22 ` Krzysztof Kozlowski
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