Re: [PATCH v3] PCI: Use pcie_find_root_port() to get root port of both PCI/PCIe device

[Bjorn Helgaas <helgaas@kernel.org>]

On Sat, May 09, 2020 at 06:19:28PM +0800, Yicong Yang wrote:
> Previously we use pcie_find_root_port() to get root port from a pcie
> device, use pci_find_pcie_root_port() to get root port from a pci
> device, which increase the complexity.
> 
> Unify the two functions and use pcie_find_root_port() to get root
> port from both pci device and pcie device. Then there is no need to
> distinguish the type of the device.
> 
> The callers of the function list below, they'll get no functional
> change:
> - iwl_trans_pcie_dump_regs()
> - pcie_root_rcb_set()
> - aer_inject()
> - acpi_pci_bridge_d3()
> - pci_configure_relaxed_ordering()
> 
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> Acked-by: Kalle Valo <kvalo@codeaurora.org> // for wireless
> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> // for thunderbolt

Applied to pci/misc for v5.8, thanks!

> ---
> Change since v2:
> - archive the callers in the commit message
> - rename pci_pcie_find_root_port() as pcie_find_root_port()
> - use pci_upstream_bridge() to traverse the chain
> Link: https://lore.kernel.org/linux-pci/1588768976-4852-1-git-send-email-yangyicong@hisilicon.com/
> 
> Change since v1:
> - Add Mika's Ack for thunderbolt part
> - Add description for pci_pcie_find_root_port()
> 
>  drivers/pci/pci-acpi.c       |  2 +-
>  drivers/pci/pci.c            | 24 ------------------------
>  drivers/pci/probe.c          |  2 +-
>  drivers/pci/quirks.c         |  2 +-
>  drivers/thunderbolt/switch.c |  4 ++--
>  include/linux/pci.h          | 23 ++++++++++++++---------
>  6 files changed, 19 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index 0c02d50..d401370 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -948,7 +948,7 @@ static bool acpi_pci_bridge_d3(struct pci_dev *dev)
>  	 * Look for a special _DSD property for the root port and if it
>  	 * is set we know the hierarchy behind it supports D3 just fine.
>  	 */
> -	root = pci_find_pcie_root_port(dev);
> +	root = pcie_find_root_port(dev);
>  	if (!root)
>  		return false;
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index d828ca8..fc5e7b6 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -695,30 +695,6 @@ struct resource *pci_find_resource(struct pci_dev *dev, struct resource *res)
>  EXPORT_SYMBOL(pci_find_resource);
> 
>  /**
> - * pci_find_pcie_root_port - return PCIe Root Port
> - * @dev: PCI device to query
> - *
> - * Traverse up the parent chain and return the PCIe Root Port PCI Device
> - * for a given PCI Device.
> - */
> -struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
> -{
> -	struct pci_dev *bridge, *highest_pcie_bridge = dev;
> -
> -	bridge = pci_upstream_bridge(dev);
> -	while (bridge && pci_is_pcie(bridge)) {
> -		highest_pcie_bridge = bridge;
> -		bridge = pci_upstream_bridge(bridge);
> -	}
> -
> -	if (pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT)
> -		return NULL;
> -
> -	return highest_pcie_bridge;
> -}
> -EXPORT_SYMBOL(pci_find_pcie_root_port);
> -
> -/**
>   * pci_wait_for_pending - wait for @mask bit(s) to clear in status word @pos
>   * @dev: the PCI device to operate on
>   * @pos: config space offset of status word
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 512cb43..554cdca 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2015,7 +2015,7 @@ static void pci_configure_relaxed_ordering(struct pci_dev *dev)
>  	 * For now, we only deal with Relaxed Ordering issues with Root
>  	 * Ports. Peer-to-Peer DMA is another can of worms.
>  	 */
> -	root = pci_find_pcie_root_port(dev);
> +	root = pcie_find_root_port(dev);
>  	if (!root)
>  		return;
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 29f473e..7aeeda5 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4253,7 +4253,7 @@ DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_AMD, 0x1a02, PCI_CLASS_NOT_DEFINED,
>   */
>  static void quirk_disable_root_port_attributes(struct pci_dev *pdev)
>  {
> -	struct pci_dev *root_port = pci_find_pcie_root_port(pdev);
> +	struct pci_dev *root_port = pcie_find_root_port(pdev);
> 
>  	if (!root_port) {
>  		pci_warn(pdev, "PCIe Completion erratum may cause device errors\n");
> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> index a2ce990..d92c755 100644
> --- a/drivers/thunderbolt/switch.c
> +++ b/drivers/thunderbolt/switch.c
> @@ -263,7 +263,7 @@ static void nvm_authenticate_start_dma_port(struct tb_switch *sw)
>  	 * itself. To be on the safe side keep the root port in D0 during
>  	 * the whole upgrade process.
>  	 */
> -	root_port = pci_find_pcie_root_port(sw->tb->nhi->pdev);
> +	root_port = pcie_find_root_port(sw->tb->nhi->pdev);
>  	if (root_port)
>  		pm_runtime_get_noresume(&root_port->dev);
>  }
> @@ -272,7 +272,7 @@ static void nvm_authenticate_complete_dma_port(struct tb_switch *sw)
>  {
>  	struct pci_dev *root_port;
> 
> -	root_port = pci_find_pcie_root_port(sw->tb->nhi->pdev);
> +	root_port = pcie_find_root_port(sw->tb->nhi->pdev);
>  	if (root_port)
>  		pm_runtime_put(&root_port->dev);
>  }
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 3840a54..98fb495 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1011,7 +1011,6 @@ void pci_bus_add_device(struct pci_dev *dev);
>  void pci_read_bridge_bases(struct pci_bus *child);
>  struct resource *pci_find_parent_resource(const struct pci_dev *dev,
>  					  struct resource *res);
> -struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev);
>  u8 pci_swizzle_interrupt_pin(const struct pci_dev *dev, u8 pin);
>  int pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge);
>  u8 pci_common_swizzle(struct pci_dev *dev, u8 *pinp);
> @@ -2124,17 +2123,23 @@ static inline int pci_pcie_type(const struct pci_dev *dev)
>  	return (pcie_caps_reg(dev) & PCI_EXP_FLAGS_TYPE) >> 4;
>  }
> 
> +/**
> + * pcie_find_root_port - Get the PCIe root port device
> + * @dev: PCI device
> + *
> + * Traverse up the parent chain and return the PCIe Root Port PCI Device
> + * for a given PCI/PCIe Device.
> + */
>  static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev)
>  {
> -	while (1) {
> -		if (!pci_is_pcie(dev))
> -			break;
> -		if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
> -			return dev;
> -		if (!dev->bus->self)
> -			break;
> -		dev = dev->bus->self;
> +	struct pci_dev *root_port = pci_upstream_bridge(dev);
> +
> +	while (root_port) {
> +		if (pci_pcie_type(root_port) == PCI_EXP_TYPE_ROOT_PORT)
> +			return root_port;
> +		root_port = pci_upstream_bridge(root_port);
>  	}
> +
>  	return NULL;
>  }
> 
> --
> 2.8.1
>