linux-kernel - Re: (subset) [PATCH v3 0/4] PCI/pwrctrl: Allow pwrctrl framework to control PERST# if available

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Message-Id: <175810383525.37722.6338178642788441926.b4-ty@kernel.org>
Date: Wed, 17 Sep 2025 15:40:35 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: 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>, Saravana Kannan <saravanak@...gle.com>, 
 Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
Cc: linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>, 
 Brian Norris <briannorris@...omium.org>, Bjorn Helgaas <helgaas@...nel.org>
Subject: Re: (subset) [PATCH v3 0/4] PCI/pwrctrl: Allow pwrctrl framework
 to control PERST# if available


On Fri, 12 Sep 2025 14:05:00 +0530, Manivannan Sadhasivam wrote:
> This series is the proper version for toggling PERST# from the pwrctrl
> framework after the initial RFC posted earlier [1].
> 
> Problem statement
> =================
> 
> Pwrctrl framework is intented to control the supplies to the components on the
> PCI bus. However, if the platform supports the PERST# signal, it should be
> toggled as per the requirements in the electromechanical specifications like
> PCIe CEM, Mini, and M.2. Since the pwrctrl framework is controlling the power
> supplies, it should also toggle PERST# as per the requirements in the above
> mentioned specifications. Right now, it is just controlling the power to the
> components and rely on controller drivers to toggle PERST#, which goes against
> the specs. For instance, controller drivers will deassert PERST# even before the
> pwrctrl driver enables the supplies. This causes the device to see PERST#
> deassert immediately after power on, thereby violating the delay requirements in
> the PCI Electromechanical specs.
> 
> [...]

Applied, thanks!

[2/4] PCI: qcom: Move host bridge 'phy' and 'reset' pointers to struct qcom_pcie_port
      commit: af8df709bf365f5583d31091280354e1ef0b201f

Best regards,
-- 
Manivannan Sadhasivam <mani@...nel.org>