Re: [PATCH 06/10] usb: chipidea: msm: keep the glue device runtime-active

From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>,
	Bartosz Golaszewski <brgl@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Linus Walleij <linusw@kernel.org>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Xu Yang <xu.yang_2@nxp.com>, Peng Fan <peng.fan@nxp.com>,
	Vinod Koul <vkoul@kernel.org>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Peter Chen <peter.chen@kernel.org>,
	Pavankumar Kondeti <quic_pkondeti@quicinc.com>,
	Stephen Boyd <stephen.boyd@linaro.org>,
	Konrad Dybcio <konradybcio@kernel.org>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-gpio@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-usb@vger.kernel.org, linux-phy@lists.infradead.org,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Peter Chen <peter.chen@nxp.com>
Subject: Re: [PATCH 06/10] usb: chipidea: msm: keep the glue device runtime-active
Date: Tue, 18 Aug 2026 12:02:14 +0200	[thread overview]
Message-ID: <c72378dd-edde-49c9-833f-d107f6573989@oss.qualcomm.com> (raw)
In-Reply-To: <20260810-msm8974-usb-hsic-v1-6-e5f93ea76ffa@oss.qualcomm.com>

On 8/10/26 5:42 PM, Dmitry Baryshkov wrote:
> The msm chipidea glue enables runtime PM with pm_runtime_no_callbacks()
> and nothing pinning it active. Right after a successful probe the
> driver core's pm_request_idle() runtime-suspends the glue (the ci core
> child has runtime PM disabled, so it does not hold its parent), and
> when the glue sits in a power domain - the HSIC instances live in the
> USB_HS_HSIC GDSC on msm8974 - genpd then powers the domain off
> underneath the running controller. The EHCI register file reads back
> zeroes, an onboard hub's connect is never seen, and subsequent bus
> accesses into the unpowered block wedge the interconnect, eventually
> taking the whole SoC down.
> 
> Pin the glue runtime-active so the domain stays powered for the
> lifetime of the controller. Proper low-power handling can later be
> built on the child's runtime PM together with the HSIC wakeup
> interrupt.
> 
> Fixes: 2d0cdcc5a0e4 ("USB: gadget: Implement runtime PM for MSM bus glue driver")
> Assisted-by: Claude:claude-fable-5
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> ---

FWIW downstream seems to implement "real" runpm, so perhaps your
agent can have some fun with that

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad

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