Re: [PATCH] PCI: host-generic: Move bridge allocation outside of pci_host_common_init()

From: Radu Rendec

Date: Thu Nov 20 2025 - 12:58:47 EST

On Thu, 2025-11-20 at 11:36 +0000, Marc Zyngier wrote:
> Having the host bridge allocation inside pci_host_common_init() results
> in a lot of complexity in the pcie-apple driver (the only direct user
> of this function outside of code PCI code).
^^^^
nit: s/code/core :)

> It forces the allocation of driver-specific tracking structures outside
> of the bridge allocation, which in turns requires it to use inneficient
> data structures to match the bridge and the private structre as needed.
>
> Instead, let the bridge structure be passed to pci_host_common_init(),
> allowing the driver to allocate it together with the private data,
> as it is usually intended. The driver can then retrieve the bridge
> via the owning device attached to the PCI config window structure.
> This allows the pcie-apple driver to be significantly simplified.
>
> Both core and driver code are changed in one go to avoid going via
> a transitional interface.
>
> Link: https://lore.kernel.org/r/86jyzms036.wl-maz@xxxxxxxxxx
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: Radu Rendec <rrendec@xxxxxxxxxx>
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: Manivannan Sadhasivam <mani@xxxxxxxxxx>
> Cc: Rob Herring <robh@xxxxxxxxxx>
> Cc: Krzysztof Wilczyński <kwilczynski@xxxxxxxxxx>
> Cc: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>
> ---
> drivers/pci/controller/pci-host-common.c | 13 ++++----
> drivers/pci/controller/pci-host-common.h | 1 +
> drivers/pci/controller/pcie-apple.c | 42 ++++--------------------
> 3 files changed, 14 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
> index 810d1c8de24e9..c473e7c03baca 100644
> --- a/drivers/pci/controller/pci-host-common.c
> +++ b/drivers/pci/controller/pci-host-common.c
> @@ -53,16 +53,12 @@ struct pci_config_window *pci_host_common_ecam_create(struct device *dev,
> EXPORT_SYMBOL_GPL(pci_host_common_ecam_create);
>
> int pci_host_common_init(struct platform_device *pdev,
> + struct pci_host_bridge *bridge,
> const struct pci_ecam_ops *ops)
> {
> struct device *dev = &pdev->dev;
> - struct pci_host_bridge *bridge;
> struct pci_config_window *cfg;
>
> - bridge = devm_pci_alloc_host_bridge(dev, 0);
> - if (!bridge)
> - return -ENOMEM;
> -
> of_pci_check_probe_only();
>
> platform_set_drvdata(pdev, bridge);
> @@ -85,12 +81,17 @@ EXPORT_SYMBOL_GPL(pci_host_common_init);
> int pci_host_common_probe(struct platform_device *pdev)
> {
> const struct pci_ecam_ops *ops;
> + struct pci_host_bridge *bridge;
>
> ops = of_device_get_match_data(&pdev->dev);
> if (!ops)
> return -ENODEV;
>
> - return pci_host_common_init(pdev, ops);
> + bridge = devm_pci_alloc_host_bridge(&pdev->dev, 0);
> + if (!bridge)
> + return -ENOMEM;
> +
> + return pci_host_common_init(pdev, bridge, ops);
> }
> EXPORT_SYMBOL_GPL(pci_host_common_probe);
>
> diff --git a/drivers/pci/controller/pci-host-common.h b/drivers/pci/controller/pci-host-common.h
> index 51c35ec0cf37d..b5075d4bd7eb3 100644
> --- a/drivers/pci/controller/pci-host-common.h
> +++ b/drivers/pci/controller/pci-host-common.h
> @@ -14,6 +14,7 @@ struct pci_ecam_ops;
>
> int pci_host_common_probe(struct platform_device *pdev);
> int pci_host_common_init(struct platform_device *pdev,
> + struct pci_host_bridge *bridge,
> const struct pci_ecam_ops *ops);
> void pci_host_common_remove(struct platform_device *pdev);
>
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index 0380d300adca6..a902aa81a497e 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -206,9 +206,6 @@ struct apple_pcie_port {
> int idx;
> };
>
> -static LIST_HEAD(pcie_list);
> -static DEFINE_MUTEX(pcie_list_lock);
> -
> static void rmw_set(u32 set, void __iomem *addr)
> {
> writel_relaxed(readl_relaxed(addr) | set, addr);
> @@ -724,32 +721,9 @@ static int apple_msi_init(struct apple_pcie *pcie)
> return 0;
> }
>
> -static void apple_pcie_register(struct apple_pcie *pcie)
> -{
> - guard(mutex)(&pcie_list_lock);
> -
> - list_add_tail(&pcie->entry, &pcie_list);
> -}
> -
> -static void apple_pcie_unregister(struct apple_pcie *pcie)
> -{
> - guard(mutex)(&pcie_list_lock);
> -
> - list_del(&pcie->entry);
> -}
> -
> static struct apple_pcie *apple_pcie_lookup(struct device *dev)
> {
> - struct apple_pcie *pcie;
> -
> - guard(mutex)(&pcie_list_lock);
> -
> - list_for_each_entry(pcie, &pcie_list, entry) {
> - if (pcie->dev == dev)
> - return pcie;
> - }
> -
> - return NULL;
> + return pci_host_bridge_priv(dev_get_drvdata(dev));
> }
>
>

You forgot to remove the `entry` field from struct apple_pcie. It's no
longer needed now that pcie_list is gone.

>
> static struct apple_pcie_port *apple_pcie_get_port(struct pci_dev *pdev)
> @@ -875,13 +849,15 @@ static const struct pci_ecam_ops apple_pcie_cfg_ecam_ops = {
> static int apple_pcie_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> + struct pci_host_bridge *bridge;
> struct apple_pcie *pcie;
> int ret;
>
> - pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> - if (!pcie)
> + bridge = devm_pci_alloc_host_bridge(dev, sizeof(*pcie));
> + if (!bridge)
> return -ENOMEM;
>
> + pcie = pci_host_bridge_priv(bridge);
> pcie->dev = dev;
> pcie->hw = of_device_get_match_data(dev);
> if (!pcie->hw)
> @@ -897,13 +873,7 @@ static int apple_pcie_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> - apple_pcie_register(pcie);
> -
> - ret = pci_host_common_init(pdev, &apple_pcie_cfg_ecam_ops);
> - if (ret)
> - apple_pcie_unregister(pcie);
> -
> - return ret;
> + return pci_host_common_init(pdev, bridge, &apple_pcie_cfg_ecam_ops);
> }
>
> static const struct of_device_id apple_pcie_of_match[] = {

With those two nitpicks addressed,

Reviewed-by: Radu Rendec <rrendec@xxxxxxxxxx>

And thanks again for spending time on this and creating the patch.

--
Radu