From: Georgi Djakov <georgi.djakov@linaro.org>
To: Rob Herring <robh@kernel.org>
Cc: vireshk@kernel.org, sboyd@kernel.org, nm@ti.com,
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 1/4] dt-bindings: opp: Introduce opp-bw-MBs bindings
Date: Tue, 9 Apr 2019 17:39:08 +0300 [thread overview]
Message-ID: <6d918bd9-489c-89fa-733e-90a5dabdaa0c@linaro.org> (raw)
In-Reply-To: <20190328151255.GA5262@bogus>
Hi Rob,
On 3/28/19 17:12, Rob Herring wrote:
> On Wed, Mar 13, 2019 at 11:00:07AM +0200, 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.
>
> How would this work if you have 1 OPP (for the bus/interconnect/ddr) and
> 2 devices with variable bandwidth needs? Or 'device' here means the
> interconnect?
This is a property of the consumer devices and not of the bus. It's fine
for devices to have different bandwidth needs and to be connected to a
shared bus. In this case the framework knows the topology and can
determine which parts of the bus are shared and aggregate the traffic
accordingly.
>>
>> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
>> ---
>> Documentation/devicetree/bindings/opp/opp.txt | 45 +++++++++++++++++++
>> 1 file changed, 45 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
>> index 76b6c79604a5..fa598264615f 100644
>> --- a/Documentation/devicetree/bindings/opp/opp.txt
>> +++ b/Documentation/devicetree/bindings/opp/opp.txt
>> @@ -129,6 +129,9 @@ Optional properties:
>> - opp-microamp-<name>: Named opp-microamp property. Similar to
>> opp-microvolt-<name> property, but for microamp instead.
>>
>> +- opp-bw-MBs: The interconnect bandwidth is specified with an array containing
>> + the two integer values for average and peak bandwidth in megabytes per second.
>
> -MBps would be better IMO. Either way, units should be documented in
> property-units.txt.
Agree! Of course!
Thanks,
Georgi
next prev parent reply other threads:[~2019-04-09 14:39 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-13 9:00 [PATCH 0/4] Introduce OPP bandwidth bindings Georgi Djakov
2019-03-13 9:00 ` [PATCH 1/4] dt-bindings: opp: Introduce opp-bw-MBs bindings Georgi Djakov
2019-03-14 6:23 ` Viresh Kumar
2019-04-09 14:36 ` Georgi Djakov
2019-04-10 4:05 ` Viresh Kumar
2019-04-10 9:52 ` Georgi Djakov
2019-03-28 15:12 ` Rob Herring
2019-04-09 14:39 ` Georgi Djakov [this message]
2019-03-13 9:00 ` [PATCH 2/4] OPP: Add support for parsing the interconnect bandwidth Georgi Djakov
2019-03-14 6:30 ` Viresh Kumar
2019-04-09 14:37 ` Georgi Djakov
2019-04-10 3:53 ` Viresh Kumar
2019-03-13 9:00 ` [PATCH 3/4] OPP: Update the bandwidth on OPP frequency changes Georgi Djakov
2019-03-13 9:00 ` [PATCH 4/4] cpufreq: dt: Add support for interconnect bandwidth scaling Georgi Djakov
2019-03-15 19:02 ` [PATCH 0/4] Introduce OPP bandwidth bindings Sibi Sankar
2019-03-28 15:16 ` Rob Herring
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