From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
To: "Ramón Jesús Miranda" <ramonjesusmiranda@gmail.com>,
"Bjorn Andersson" <andersson@kernel.org>,
"Konrad Dybcio" <konradybcio@kernel.org>,
"Krzysztof Kozlowski" <krzk@kernel.org>
Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] soc: qcom: icc-bwmon: drop the bandwidth vote across system suspend
Date: Mon, 19 Oct 2026 10:40:15 +0200 [thread overview]
Message-ID: <73ab680a-ad47-4270-a7e9-48df70e86fed@oss.qualcomm.com> (raw)
In-Reply-To: <20261018155424.1299645-1-ramonjesusmiranda@gmail.com>
On 10/18/26 5:54 PM, Ramón Jesús Miranda wrote:
> icc-bwmon has no PM ops: the interconnect vote derived from the last
> sample stays in place while the system is suspended. On X1E80100 the CPU
> bwmon was left voting 800 MB/s peak on the DDR path during s2idle, which
> keeps DDR out of its low power modes (the qcom_stats "ddr" counter never
> advances).
>
> Disable the monitor, drop the OPP vote on suspend and restart monitoring
> on resume. With this change DDR reaches its low power mode for >99% of
> s2idle on a Microsoft Surface Pro 11 (X1E80100).
Have you done a negative test (does reverting this patch alone break
ddr collapse for you)? The DT uses ACTIVE_ONLY icc votes for BWMON,
so as the CPU subsystem goes to sleep, these votes are removed in
hardware.
Konrad
prev parent reply other threads:[~2026-10-19 8:40 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-18 15:54 Ramón Jesús Miranda
2026-10-19 8:40 ` Konrad Dybcio [this message]
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