From: Viresh Kumar <viresh.kumar@linaro.org>
To: Saravana Kannan <saravanak@google.com>
Cc: Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
Stephen Boyd <sboyd@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Georgi Djakov <georgi.djakov@linaro.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
"Sweeney, Sean" <seansw@qti.qualcomm.com>,
David Dai <daidavid1@codeaurora.org>,
adharmap@codeaurora.org, Rajendra Nayak <rnayak@codeaurora.org>,
Sibi Sankar <sibis@codeaurora.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Evan Green <evgreen@chromium.org>,
Android Kernel Team <kernel-team@android.com>,
Linux PM <linux-pm@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 2/3] OPP: Add support for bandwidth OPP tables
Date: Fri, 10 Jan 2020 12:24:20 +0530 [thread overview]
Message-ID: <20200110065420.3bp4fjj2wbezoyrc@vireshk-i7> (raw)
In-Reply-To: <CAGETcx_1B8AfxBuJ9Mbq8BNx-fYyP8pOnF6caN=ooyPARaaJ3A@mail.gmail.com>
On 09-01-20, 10:35, Saravana Kannan wrote:
> Agreed for the example you are giving where PM domains/voltages are
> dropped automatically when dropping the device freq to suspend freq.
> I'm just wondering about a different scenario where if some power
> domain needed to be at say 0.5v when it's suspended (no consumer using
> it)
The domain should be powered off in this case I think.
> to not lose state, or to come back up without brownouts, etc then
> suspend OPP for PM domains might be useful. But I don't know enough
> about that to speak with authority, so I'll leave it at this.
>
> I see this suspend-opp as a way to mark to what level the bandwidth
> needs to be dropped to/brought back up from during suspend/resume by
> the driver making interconnect bandwidth requests. For example, what
> if the CPU -> DDR needed to be at some level to avoid suspend/resume
> issues (say CPU bug with respect to timing/latencies)? In this
> example, the CPU driver would be the one making bandwidth requests for
> CPU -> DDR bandwidth during normal operation and during
> suspend/resume. So it's basically exactly the same way it would treat
> CPU freq OPP.
I understand your concerns but to me it all looks hypothetical right
now. I am not saying we won't support suspend-opp for interconnect or
domains, but that we should do it only if it is required.
> Btw, I don't have a strong opinion on this. But, even if we do only a
> rate comparison, what does it even mean to compare rates for genpd or
> BW opp tables?
We will never do the comparison because those tables will never have
the suspend OPP in the respective tables.
--
viresh
next prev parent reply other threads:[~2020-01-10 6:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-07 0:24 [PATCH v6 0/3] Introduce Bandwidth OPPs for interconnects Saravana Kannan
2019-12-07 0:24 ` [PATCH v6 1/3] dt-bindings: opp: Introduce opp-peak-kBps and opp-avg-kBps bindings Saravana Kannan
2020-01-08 10:32 ` Viresh Kumar
2020-01-09 0:32 ` Saravana Kannan
2019-12-07 0:24 ` [PATCH v6 2/3] OPP: Add support for bandwidth OPP tables Saravana Kannan
2020-01-07 19:28 ` Sibi Sankar
2020-01-08 6:16 ` Saravana Kannan
2020-01-29 13:40 ` Sibi Sankar
2020-01-08 10:53 ` Viresh Kumar
2020-01-09 0:58 ` Saravana Kannan
2020-01-09 4:31 ` Viresh Kumar
2020-01-09 18:35 ` Saravana Kannan
2020-01-10 6:54 ` Viresh Kumar [this message]
2019-12-07 0:24 ` [PATCH v6 3/3] OPP: Add helper function " Saravana Kannan
2020-01-08 11:19 ` Viresh Kumar
2020-01-09 0:58 ` Saravana Kannan
2020-01-09 3:36 ` Saravana Kannan
2020-01-09 4:41 ` Viresh Kumar
2020-01-09 4:40 ` Viresh Kumar
2020-01-09 18:44 ` Saravana Kannan
2020-01-10 7:01 ` Viresh Kumar
2020-01-14 10:34 ` [PATCH v6 0/3] Introduce Bandwidth OPPs for interconnects Viresh Kumar
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