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Message-ID: <20240219102834.x22ggazkmzppsdxc@vireshk-i7>
Date: Mon, 19 Feb 2024 15:58:34 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: Manivannan Sadhasivam <mani@...nel.org>,
Krishna chaitanya chundru <quic_krichai@...cinc.com>,
Bjorn Andersson <andersson@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof WilczyĆski <kw@...ux.com>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Johan Hovold <johan+linaro@...nel.org>,
Brian Masney <bmasney@...hat.com>,
Georgi Djakov <djakov@...nel.org>, linux-arm-msm@...r.kernel.org,
vireshk@...nel.org, quic_vbadigan@...cinc.com,
quic_skananth@...cinc.com, quic_nitegupt@...cinc.com,
linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 5/6] arm64: dts: qcom: sm8450: Add opp table support
to PCIe
On 09-02-24, 22:14, Konrad Dybcio wrote:
> On 2.02.2024 08:33, Viresh Kumar wrote:
> > On 01-02-24, 15:45, Konrad Dybcio wrote:
> >> I'm lukewarm on this.
> >>
> >> A *lot* of hardware has more complex requirements than "x MBps at y MHz",
> >> especially when performance counters come into the picture for dynamic
> >> bw management.
> >>
> >> OPP tables can't really handle this properly.
> >
> > There was a similar concern for voltages earlier on and we added the capability
> > of adjusting the voltage for OPPs in the OPP core. Maybe something similar can
> > be done here ?
> >
> I really don't think it's fitting.. At any moment the device may require any
> bandwidth value between 0 and MAX_BW_PER_LINK_GEN * LINK_WIDTH..
Okay, I leave it up to you guys to decide on how you want to do it. I still
believe getting the information via DT is the right thing, but maybe I still
don't understand the problem fully.
Thanks.
--
viresh
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