linux-kernel - Re: [PATCH 4/5] PCI/pwrctrl: Add APIs to power on/off the pwrctrl devices

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Message-ID: <CAMRc=Mf=dwXNY-1oy9mv7GcqSjrjfcJLmKbVDtBYzqqzvahKng@mail.gmail.com>
Date: Tue, 25 Nov 2025 05:40:28 -0800
From: Bartosz Golaszewski <brgl@...ev.pl>
To: manivannan.sadhasivam@....qualcomm.com
Cc: Manivannan Sadhasivam via B4 Relay <devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org>, 
	linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Chen-Yu Tsai <wens@...nel.org>, 
	Brian Norris <briannorris@...omium.org>, 
	Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>, Niklas Cassel <cassel@...nel.org>, 
	Alex Elder <elder@...cstar.com>, Manivannan Sadhasivam <mani@...nel.org>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kwilczynski@...nel.org>, 
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>, 
	Bartosz Golaszewski <brgl@...ev.pl>
Subject: Re: [PATCH 4/5] PCI/pwrctrl: Add APIs to power on/off the pwrctrl devices

On Mon, 24 Nov 2025 17:20:47 +0100, Manivannan Sadhasivam via B4 Relay
<devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org> said:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
>
> To fix PCIe bridge resource allocation issues when powering PCIe
> switches with the pwrctrl driver, introduce APIs to explicitly power
> on and off all related devices simultaneously.
>
> Previously, the individual pwrctrl drivers powered on/off the PCIe devices
> autonomously, without any control from the controller drivers. But to
> enforce ordering w.r.t powering on the devices, these APIs will power
> on/off all the devices at the same time.
>
> The pci_pwrctrl_power_on_devices() API recursively scans the PCI child
> nodes, makes sure that pwrctrl drivers are bind to devices, and calls their
> power_on() callbacks.
>
> Similarly, pci_pwrctrl_power_off_devices() API powers off devices
> recursively via their power_off() callbacks.
>
> These APIs are expected to be called during the controller probe and
> suspend/resume time to power on/off the devices. But before calling these
> APIs, the pwrctrl devices should've been created beforehand using the
> pci_pwrctrl_{create/destroy}_devices() APIs.
>
> Co-developed-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> ---

Makes sense.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>