LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Viresh Kumar <viresh.kumar@linaro.org>
To: Rajendra Nayak <rnayak@codeaurora.org>
Cc: Georgi Djakov <georgi.djakov@linaro.org>,
	vireshk@kernel.org, sboyd@kernel.org, nm@ti.com,
	robh+dt@kernel.org, mark.rutland@arm.com, rjw@rjwysocki.net,
	jcrouse@codeaurora.org, vincent.guittot@linaro.org,
	bjorn.andersson@linaro.org, amit.kucheria@linaro.org,
	seansw@qti.qualcomm.com, daidavid1@codeaurora.org,
	evgreen@chromium.org, sibis@codeaurora.org,
	linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH v2 1/5] dt-bindings: opp: Introduce bandwidth-MBps bindings
Date: Wed, 24 Apr 2019 12:19:42 +0530
Message-ID: <20190424064942.v5g6jr5l3xy5z3xv@vireshk-i7> (raw)
In-Reply-To: <e35223d0-80ac-5236-2b8d-7f46cd3a1581@codeaurora.org>

On 24-04-19, 12:16, Rajendra Nayak wrote:
> 
> 
> On 4/23/2019 6:58 PM, Georgi Djakov wrote:
> > In addition to frequency and voltage, some devices may have bandwidth
> > requirements for their interconnect throughput - for example a CPU
> > or GPU may also need to increase or decrease their bandwidth to DDR
> > memory based on the current operating performance point.
> > 
> > Extend the OPP tables with additional property to describe the bandwidth
> > needs of a device. The average and peak bandwidth values depend on the
> > hardware and its properties.
> > 
> > Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
> > ---
> >   Documentation/devicetree/bindings/opp/opp.txt | 38 +++++++++++++++++++
> >   .../devicetree/bindings/property-units.txt    |  4 ++
> >   2 files changed, 42 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> > index 76b6c79604a5..830f0206aea7 100644
> > --- a/Documentation/devicetree/bindings/opp/opp.txt
> > +++ b/Documentation/devicetree/bindings/opp/opp.txt
> > @@ -132,6 +132,9 @@ Optional properties:
> >   - opp-level: A value representing the performance level of the device,
> >     expressed as a 32-bit integer.
> > +- bandwidth-MBps: The interconnect bandwidth is specified with an array containing
> > +  the two integer values for average and peak bandwidth in megabytes per second.
> > +
> >   - clock-latency-ns: Specifies the maximum possible transition latency (in
> >     nanoseconds) for switching to this OPP from any other OPP.
> > @@ -546,3 +549,38 @@ Example 6: opp-microvolt-<name>, opp-microamp-<name>:
> >   		};
> >   	};
> >   };
> > +
> > +Example 7: bandwidth-MBps:
> > +Average and peak bandwidth values for the interconnects between CPU and DDR
> > +memory and also between CPU and L3 are defined per each OPP. Bandwidth of both
> > +interconnects is scaled together with CPU frequency.
> > +
> > +/ {
> > +	cpus {
> > +		CPU0: cpu@0 {
> > +			compatible = "arm,cortex-a53", "arm,armv8";
> > +			...
> > +			operating-points-v2 = <&cpu_opp_table>;
> > +			/* path between CPU and DDR memory and CPU and L3 */
> > +			interconnects = <&noc MASTER_CPU &noc SLAVE_DDR>,
> > +					<&noc MASTER_CPU &noc SLAVE_L3>;
> > +		};
> > +	};
> > +
> > +	cpu_opp_table: cpu_opp_table {
> > +		compatible = "operating-points-v2";
> > +		opp-shared;
> > +
> > +		opp-200000000 {
> > +			opp-hz = /bits/ 64 <200000000>;
> > +			/* CPU<->DDR bandwidth: 457 MB/s average, 1525 MB/s peak */
> > +			 * CPU<->L3 bandwidth: 914 MB/s average, 3050 MB/s peak */
> > +			bandwidth-MBps = <457 1525>, <914 3050>;
> 
> Should this also have a bandwidth-MBps-name perhaps? Without that I guess we assume
> the order in which we specify the interconnects is the same as the order here?

Right, so I suggested not to add the -name property and to rely on the
order. Though I missed that he hasn't mentioned the order thing here.

@Georgi: Please mention above in the binding that the order is same as
interconnects binding.

-- 
viresh

  reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-23 13:28 [PATCH v2 0/5] Introduce OPP bandwidth bindings Georgi Djakov
2019-04-23 13:28 ` [PATCH v2 1/5] dt-bindings: opp: Introduce bandwidth-MBps bindings Georgi Djakov
2019-04-24  5:33   ` Viresh Kumar
2019-04-24  6:46   ` Rajendra Nayak
2019-04-24  6:49     ` Viresh Kumar [this message]
2019-04-24  9:00       ` Sibi Sankar
2019-04-24  9:05         ` Viresh Kumar
2019-04-25  4:24         ` Bjorn Andersson
2019-04-24  8:44   ` Sibi Sankar
2019-04-23 13:28 ` [PATCH v2 2/5] interconnect: Add of_icc_get_by_index() helper function Georgi Djakov
2019-05-07 11:59   ` Sibi Sankar
2019-06-27  5:56     ` Sibi Sankar
2019-04-23 13:28 ` [PATCH v2 3/5] OPP: Add support for parsing the interconnect bandwidth Georgi Djakov
2019-04-24  5:52   ` Viresh Kumar
2019-06-27  6:27     ` Sibi Sankar
2019-04-23 13:28 ` [PATCH v2 4/5] OPP: Update the bandwidth on OPP frequency changes Georgi Djakov
2019-04-24  5:55   ` Viresh Kumar
2019-04-24 10:05   ` Sibi Sankar
2019-04-23 13:28 ` [PATCH v2 5/5] cpufreq: dt: Add support for interconnect bandwidth scaling Georgi Djakov
2019-06-01  2:12 ` [PATCH v2 0/5] Introduce OPP bandwidth bindings Saravana Kannan
2019-06-03 15:56   ` Jordan Crouse
2019-06-03 19:12     ` Saravana Kannan

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190424064942.v5g6jr5l3xy5z3xv@vireshk-i7 \
    --to=viresh.kumar@linaro.org \
    --cc=amit.kucheria@linaro.org \
    --cc=bjorn.andersson@linaro.org \
    --cc=daidavid1@codeaurora.org \
    --cc=devicetree@vger.kernel.org \
    --cc=evgreen@chromium.org \
    --cc=georgi.djakov@linaro.org \
    --cc=jcrouse@codeaurora.org \
    --cc=linux-arm-msm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=nm@ti.com \
    --cc=rjw@rjwysocki.net \
    --cc=rnayak@codeaurora.org \
    --cc=robh+dt@kernel.org \
    --cc=sboyd@kernel.org \
    --cc=seansw@qti.qualcomm.com \
    --cc=sibis@codeaurora.org \
    --cc=vincent.guittot@linaro.org \
    --cc=vireshk@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org linux-kernel@archiver.kernel.org
	public-inbox-index lkml


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox