linux-kernel - Re: [PATCH v4 5/6] PCI: host-common: Add an API to check for any device under the Root Ports

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Message-ID: <6f2a59ee-8e0c-4dbe-8007-bbe7686d46ac@rock-chips.com>
Date: Wed, 7 Jan 2026 16:39:24 +0800
From: Shawn Lin <shawn.lin@...k-chips.com>
To: manivannan.sadhasivam@....qualcomm.com, Jingoo Han
 <jingoohan1@...il.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>
Cc: shawn.lin@...k-chips.com, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org, vincent.guittot@...aro.org,
 zhangsenchuan@...incomputing.com, Richard Zhu <hongxing.zhu@....com>,
 Frank Li <Frank.Li@....com>
Subject: Re: [PATCH v4 5/6] PCI: host-common: Add an API to check for any
 device under the Root Ports


在 2026/01/07 星期三 16:11, Manivannan Sadhasivam via B4 Relay 写道:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> 
> Some controller drivers need to check if there is any device available
> under the Root Ports. So add an API that returns 'true' if a device is
> found under any of the Root Ports, 'false' otherwise.

Reviewed-by: Shawn Lin <shawn.lin@...k-chips.com>

> 
> Reviewed-by: Frank Li <Frank.Li@....com>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> ---
>   drivers/pci/controller/pci-host-common.c | 21 +++++++++++++++++++++
>   drivers/pci/controller/pci-host-common.h |  2 ++
>   2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
> index c473e7c03bac..a88622203227 100644
> --- a/drivers/pci/controller/pci-host-common.c
> +++ b/drivers/pci/controller/pci-host-common.c
> @@ -17,6 +17,27 @@
>   
>   #include "pci-host-common.h"
>   
> +/**
> + * pci_root_ports_have_device - Check if the Root Ports under the Root bus have
> + *				any device underneath
> + * @root_bus: Root bus to check for
> + *
> + * Return: true if a device is found, false otherwise
> + */
> +bool pci_root_ports_have_device(struct pci_bus *root_bus)
> +{
> +	struct pci_bus *child;
> +
> +	/* Iterate over the Root Port busses and look for any device */
> +	list_for_each_entry(child, &root_bus->children, node) {
> +		if (!list_empty(&child->devices))
> +			return true;
> +	}
> +
> +	return false;
> +}
> +EXPORT_SYMBOL_GPL(pci_root_ports_have_device);
> +
>   static void gen_pci_unmap_cfg(void *ptr)
>   {
>   	pci_ecam_free((struct pci_config_window *)ptr);
> diff --git a/drivers/pci/controller/pci-host-common.h b/drivers/pci/controller/pci-host-common.h
> index b5075d4bd7eb..8088faf94282 100644
> --- a/drivers/pci/controller/pci-host-common.h
> +++ b/drivers/pci/controller/pci-host-common.h
> @@ -20,4 +20,6 @@ void pci_host_common_remove(struct platform_device *pdev);
>   
>   struct pci_config_window *pci_host_common_ecam_create(struct device *dev,
>   	struct pci_host_bridge *bridge, const struct pci_ecam_ops *ops);
> +
> +bool pci_root_ports_have_device(struct pci_bus *root_bus);
>   #endif
>