linux-kernel - Re: [PATCH v5 7/9] PCI: PCI: Add pcie_link_is_active() to determine if the PCIe link is active

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Message-ID: <20250412181151.GA1417992-robh@kernel.org>
Date: Sat, 12 Apr 2025 13:11:51 -0500
From: Rob Herring <robh@...nel.org>
To: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	chaitanya chundru <quic_krichai@...cinc.com>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	cros-qcom-dts-watchers@...omium.org,
	Jingoo Han <jingoohan1@...il.com>,
	Bartosz Golaszewski <brgl@...ev.pl>, quic_vbadigan@...cnic.com,
	amitk@...nel.org, linux-pci@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, jorge.ramirez@....qualcomm.com,
	Dmitry Baryshkov <lumag@...nel.org>
Subject: Re: [PATCH v5 7/9] PCI: PCI: Add pcie_link_is_active() to determine
 if the PCIe link is active

On Sat, Apr 12, 2025 at 07:19:56AM +0530, Krishna Chaitanya Chundru wrote:
> Introduce a common API to check if the PCIe link is active, replacing
> duplicate code in multiple locations.
> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> ---
>  drivers/pci/hotplug/pciehp.h      |  1 -
>  drivers/pci/hotplug/pciehp_ctrl.c |  7 ++++---
>  drivers/pci/hotplug/pciehp_hpc.c  | 33 +++------------------------------
>  drivers/pci/pci.c                 | 26 +++++++++++++++++++++++---
>  include/linux/pci.h               |  4 ++++
>  5 files changed, 34 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
> index 273dd8c66f4eff8b62ab065cebf97db3c343977d..acef728530e36d6ea4d7db3afe97ed31b85be064 100644
> --- a/drivers/pci/hotplug/pciehp.h
> +++ b/drivers/pci/hotplug/pciehp.h
> @@ -186,7 +186,6 @@ int pciehp_query_power_fault(struct controller *ctrl);
>  int pciehp_card_present(struct controller *ctrl);
>  int pciehp_card_present_or_link_active(struct controller *ctrl);
>  int pciehp_check_link_status(struct controller *ctrl);
> -int pciehp_check_link_active(struct controller *ctrl);
>  void pciehp_release_ctrl(struct controller *ctrl);
>  
>  int pciehp_sysfs_enable_slot(struct hotplug_slot *hotplug_slot);
> diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
> index d603a7aa74838c748f6ac2d22ffb8b8cfe64e469..36468a9c31d669ec916e867ecfb7a8220cfab157 100644
> --- a/drivers/pci/hotplug/pciehp_ctrl.c
> +++ b/drivers/pci/hotplug/pciehp_ctrl.c
> @@ -230,7 +230,8 @@ void pciehp_handle_disable_request(struct controller *ctrl)
>  
>  void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
>  {
> -	int present, link_active;
> +	bool link_active;
> +	int present;
>  
>  	/*
>  	 * If the slot is on and presence or link has changed, turn it off.
> @@ -260,8 +261,8 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
>  	/* Turn the slot on if it's occupied or link is up */
>  	mutex_lock(&ctrl->state_lock);
>  	present = pciehp_card_present(ctrl);
> -	link_active = pciehp_check_link_active(ctrl);
> -	if (present <= 0 && link_active <= 0) {
> +	link_active = pcie_link_is_active(ctrl->pcie->port);
> +	if (present <= 0 && !link_active) {
>  		if (ctrl->state == BLINKINGON_STATE) {
>  			ctrl->state = OFF_STATE;
>  			cancel_delayed_work(&ctrl->button_work);
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 8a09fb6083e27669a12f1a3bb2a550369d471d16..278bc21d531dd20a38e06e5d33f5ccd18131c2c3 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -221,33 +221,6 @@ static void pcie_write_cmd_nowait(struct controller *ctrl, u16 cmd, u16 mask)
>  	pcie_do_write_cmd(ctrl, cmd, mask, false);
>  }
>  
> -/**
> - * pciehp_check_link_active() - Is the link active
> - * @ctrl: PCIe hotplug controller
> - *
> - * Check whether the downstream link is currently active. Note it is
> - * possible that the card is removed immediately after this so the
> - * caller may need to take it into account.

You've lost this somewhat important comment that still exists after this 
patch.

Rob