Re: [PATCH v9 06/30] PCI: Separate pci_host_bridge creation out of pci_create_root_bus()

Bjorn Helgaas
2015-04-07T21:38:48Z

On Fri, Apr 03, 2015 at 05:25:40PM +0800, Yijing Wang wrote:
> This patch separate pci_host_bridge creation out
> of pci_create_root_bus(), and try to make a generic
> pci_host_bridge, then we could make it hold host
> bridge specific operations like
> pcibios_root_bridge_prepare(). The changes are
> transparent to platform host bridge drivers.
>
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> ---
> drivers/pci/host-bridge.c | 52 +++++++++++++++++++++
> drivers/pci/pci.h | 3 +
> drivers/pci/probe.c | 113 +++++++++++++++++++++------------------------
> 3 files changed, 108 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index 39b2dbe..7d52a0a 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -8,6 +8,58 @@
>
> #include "pci.h"
>
> +static void pci_release_host_bridge_dev(struct device *dev)
> +{
> + struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
> +
> + if (bridge->release_fn)
> + bridge->release_fn(bridge);
> +
> + pci_free_resource_list(&bridge->windows);
> + kfree(bridge);
> +}
> +
> +struct pci_host_bridge *pci_create_host_bridge(
> + struct device *parent, int domain, int bus,
> + struct list_head *resources)
> +{
> + int error;
> + struct pci_host_bridge *host;
> + struct resource_entry *window, *n;
> +
> + host = kzalloc(sizeof(*host), GFP_KERNEL);
> + if (!host)
> + return NULL;
> +
> + host->dev.parent = parent;
> + INIT_LIST_HEAD(&host->windows);
> + resource_list_for_each_entry_safe(window, n, resources)
> + list_move_tail(&window->node, &host->windows);
> + /*
> + * If support CONFIG_PCI_DOMAINS_GENERIC, use
> + * pci_host_assign_domain_nr() to update domain
> + * number.
> + */
> + host->domain = domain;
> + pci_host_assign_domain_nr(host);

I think it's a bit confusing that there's another "host->domain ="
assignment buried inside pci_host_assign_domain_nr(), so the first
assignment is overwritten when CONFIG_PCI_DOMAINS_GENERIC is set.

Can you do something like this instead:

int pci_host_assign_domain_nr(struct pci_host_bridge *host, int domain)
{
#ifdef CONFIG_PCI_DOMAINS_GENERIC
host->domain = pci_assign_domain_nr(host->dev.parent);
#else
host->domain = domain;
#endif
}

Then the alternatives (CONFIG_PCI_DOMAINS_GENERIC=y and
CONFIG_PCI_DOMAINS_GENERIC being unset) are close together and right at the
#ifdef CONFIG_PCI_DOMAINS_GENERIC, so no extra comments are needed.

Bjorn