Subject: Re: [RFC PATCH 07/16] PCI: Separate pci_host_bridge creation out of pci_create_root_bus()

From: Yijing Wang <[email-masked]>
Date: Thu, 20 Nov 2014 10:47:35 +0800

>>>> +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, u32 db,
>>>> +               struct pci_ops *ops, void *sysdata,
>>>
>>> I don't thinks it is worth moving the buses' pci_ops into pci_host_bridge. It
>>> might be more useful to have pci_host_bridge specific ops here.
>>
>> Because we want to create pci_host_bridge before pci root bus creation,
>> so when we scan the root bus and child buses, we use pci_host_bridge as
>> the only argument, and another pci_host_info will be addes in later patch,
>> which one support carry the pci_host_bridge ops.
> 
> But pci_create_root_bus() already has a pci_ops argument, I don't see the reason
> to drop that.
> 
> pci_create_host_bridge() can get pci_host_bridge ops while pci_create_root_bus() gets
> the bus ops. For find out the MSI controller, the domain number and any other HB
> specific stuff, you use the HB ops. For config R/W acceses you use bus ops.
> 

I want to unexport pci_create_root_bus() if we have pci_create_host_bridge().

>>>> -struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
>>>> -               struct pci_ops *ops, void *sysdata, struct list_head *resources)
>>>> +struct pci_bus *__pci_create_root_bus(struct pci_host_bridge *bridge)
>>>>  {
>>>>         int error;
>>>> -       struct pci_host_bridge *bridge;
>>>>         struct pci_bus *b, *b2;
>>>> -       struct pci_host_bridge_window *window, *n;
>>>> +       struct pci_host_bridge_window *window;
>>>>         struct resource *res;
>>>>         resource_size_t offset;
>>>>         char bus_addr[64];
>>>>         char *fmt;
>>>> -       u8      bus = PCI_BUSNUM(db);
>>>> +       struct device *parent = bridge->dev.parent;
>>>>
>>>>         b = pci_alloc_bus(NULL);
>>>>         if (!b)
>>>>                 return NULL;
>>>>
>>>> -       b->sysdata = sysdata;
>>>> -       b->ops = ops;
>>>> -       b->number = b->busn_res.start = bus;
>>>> +       b->sysdata = bridge->sysdata;
>>>
>>> I think bridge should be the b->sysdata here.
>>
>> ? what's the meaning?
> 
> Currently, bus->sysdata holds a pointer to the arch/driver host bridge structure, as passed
> in pci_create_root_bus(). If you agree with my idea of wrapping the host bridge driver
> structure around the pci_host_bridge, then we will always have a way of retrieving that
> information; but for backwards compatibility we could set bus->sysdata to be the bridge.
> Then existing macros that convert sysdata to pci_controller can be reused after being
> updated.

I think wrapping the host bridge driver structure around the pci_host_bridge could help
us to find the private pci_controller, but in this case, pci_host_bridge is not a pointer
so we put all pci_host_bridge init stuff in host drivers ? And if we still use arch spec
macros convert ssydata to pci_controller, so what's the greatest advantage ?

If we move domain and msi_chip out of sysdata, what's other things in sysdata still need us
to convert in PCI core ?

> 
> Best regards,
> Liviu
> 
>>
>>>
>>>> +       b->ops = bridge->ops;
>>>
>>> See comment above why I don't think this is necessary.
>>>
>>>> +       b->number = b->busn_res.start = bridge->busnum;
>>>>         pci_bus_assign_domain_nr(b, parent);
>>>> -       b2 = pci_find_bus(pci_domain_nr(b), bus);
>>>> +       bridge->domain = pci_domain_nr(b);
>>>
>>> Do you really want to overwrite the bridge's domain with the one from a bus that
>>> could possibly be rejected a couple of lines further down?
>>>
>>> As an asside: if we are doing the split of pci_host_bridge from root bus creation
>>> it is worth in my opinion to move the domain setup in pci_create_host_bridge()
>>> and stop fiddling with it here.
>>
>>
>> Hi Liviu, these lines just temporary, I will remove it after all host drivers
>> save its domain in pci_host_bridge.
>>
>>
>>>
>>> Otherwise it looks to me like you are heading in the right direction.
>>
>> Thanks!
>> Yijing.
>>
>>>
>>> Best regards,
>>> Liviu
>>>
>>>> +       b2 = pci_find_bus(pci_domain_nr(b), bridge->busnum);
>>>>         if (b2) {
>>>>                 /* If we already got to this bus through a different bridge, ignore it */
>>>>                 dev_dbg(&b2->dev, "bus already known\n");
>>>>                 goto err_out;
>>>>         }
>>>>
>>>> -       bridge = pci_alloc_host_bridge(b);
>>>> -       if (!bridge)
>>>> -               goto err_out;
>>>> -
>>>> -       bridge->dev.parent = parent;
>>>> -       bridge->dev.release = pci_release_host_bridge_dev;
>>>> -       dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
>>>> -       error = pcibios_root_bridge_prepare(bridge);
>>>> -       if (error) {
>>>> -               kfree(bridge);
>>>> -               goto err_out;
>>>> -       }
>>>> -
>>>> -       error = device_register(&bridge->dev);
>>>> -       if (error) {
>>>> -               put_device(&bridge->dev);
>>>> -               goto err_out;
>>>> -       }
>>>>         b->bridge = get_device(&bridge->dev);
>>>>         device_enable_async_suspend(b->bridge);
>>>>         pci_set_bus_of_node(b);
>>>> @@ -1950,7 +1899,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
>>>>
>>>>         b->dev.class = &pcibus_class;
>>>>         b->dev.parent = b->bridge;
>>>> -       dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), bus);
>>>> +       dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), b->number);
>>>>         error = device_register(&b->dev);
>>>>         if (error)
>>>>                 goto class_dev_reg_err;
>>>> @@ -1966,12 +1915,11 @@ struct pci_bus *pci_create_root_bus(struct device *parent, u32 db,
>>>>                 printk(KERN_INFO "PCI host bridge to bus %s\n", dev_name(&b->dev));
>>>>
>>>>         /* Add initial resources to the bus */
>>>> -       list_for_each_entry_safe(window, n, resources, list) {
>>>> -               list_move_tail(&window->list, &bridge->windows);
>>>> +       list_for_each_entry(window, &bridge->windows, list) {
>>>>                 res = window->res;
>>>>                 offset = window->offset;
>>>>                 if (res->flags & IORESOURCE_BUS)
>>>> -                       pci_bus_insert_busn_res(b, bus, res->end);
>>>> +                       pci_bus_insert_busn_res(b, b->number, res->end);
>>>>                 else
>>>>                         pci_bus_add_resource(b, res, 0);
>>>>                 if (offset) {
>>>> @@ -2001,6 +1949,25 @@ err_out:
>>>>         return NULL;
>>>>  }
>>>>
>>>> +struct pci_bus *pci_create_root_bus(struct device *parent, u32 bus,
>>>> +               struct pci_ops *ops, void *sysdata, struct list_head *resources)
>>>> +{
>>>> +       struct pci_host_bridge *host;
>>>> +
>>>> +       host = pci_create_host_bridge(parent, bus, ops,
>>>> +                       sysdata ,resources);
>>>> +       if (!host)
>>>> +               return NULL;
>>>> +
>>>> +       host->bus = __pci_create_root_bus(host);
>>>> +       if (!host->bus) {
>>>> +               pci_free_host_bridge(host);
>>>> +               return NULL;
>>>> +       }
>>>> +
>>>> +       return host->bus;
>>>> +}
>>>> +
>>>>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
>>>>  {
>>>>         struct resource *res = &b->busn_res;
>>>> @@ -2069,40 +2036,37 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
>>>>  {
>>>>         struct pci_host_bridge_window *window;
>>>>         bool found = false;
>>>> -       struct pci_bus *b;
>>>> -       LIST_HEAD(default_res);
>>>> +       struct pci_host_bridge *host;
>>>>         int max;
>>>>
>>>> -       if (!resources) {
>>>> -               pci_add_resource(&default_res, &ioport_resource);
>>>> -               pci_add_resource(&default_res, &iomem_resource);
>>>> -               pci_add_resource(&default_res, &busn_resource);
>>>> -       } else {
>>>> -               list_for_each_entry(window, resources, list)
>>>> -                       if (window->res->flags & IORESOURCE_BUS) {
>>>> -                               found = true;
>>>> -                               break;
>>>> -                       }
>>>> -       }
>>>> +       host = pci_create_host_bridge(parent, db, ops, sysdata, resources);
>>>> +       if (!host)
>>>> +               return NULL;
>>>>
>>>> -       b = pci_create_root_bus(parent, db, ops, sysdata,
>>>> -                       resources ? resources : &default_res);
>>>> -       if (!b)
>>>> +       list_for_each_entry(window, &host->windows, list)
>>>> +               if (window->res->flags & IORESOURCE_BUS) {
>>>> +                       found = true;
>>>> +                       break;
>>>> +               }
>>>> +
>>>> +       host->bus = __pci_create_root_bus(host);
>>>> +       if (!host->bus) {
>>>> +               pci_free_host_bridge(host);
>>>>                 return NULL;
>>>> +       }
>>>>
>>>>         if (!found) {
>>>> -               dev_info(&b->dev,
>>>> +               dev_info(&host->bus->dev,
>>>>                  "No busn resource found for root bus, will use [bus %02x-ff]\n",
>>>>                         PCI_BUSNUM(db));
>>>> -               pci_bus_insert_busn_res(b, PCI_BUSNUM(db), 255);
>>>> +               pci_bus_insert_busn_res(host->bus, PCI_BUSNUM(db), 255);
>>>>         }
>>>>
>>>> -       max = pci_scan_child_bus(b);
>>>> -
>>>> +       max = pci_scan_child_bus(host->bus);
>>>>         if (!found)
>>>> -               pci_bus_update_busn_res_end(b, max);
>>>> +               pci_bus_update_busn_res_end(host->bus, max);
>>>>
>>>> -       return b;
>>>> +       return host->bus;
>>>>  }
>>>>  EXPORT_SYMBOL(pci_scan_root_bus);
>>>>
>>>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>>>> index 8b11b38..daa7f40 100644
>>>> --- a/include/linux/pci.h
>>>> +++ b/include/linux/pci.h
>>>> @@ -402,7 +402,12 @@ struct pci_host_bridge_window {
>>>>  struct pci_host_bridge {
>>>>         struct device dev;
>>>>         struct pci_bus *bus;            /* root bus */
>>>> +       struct list_head list;
>>>>         struct list_head windows;       /* pci_host_bridge_windows */
>>>> +       int busnum;
>>>> +       int domain;
>>>> +       void *sysdata;
>>>> +       struct pci_ops *ops;
>>>>         void (*release_fn)(struct pci_host_bridge *);
>>>>         void *release_data;
>>>>  };
>>>> @@ -413,7 +418,9 @@ void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
>>>>                      void *release_data);
>>>>
>>>>  int pcibios_root_bridge_prepare(struct pci_host_bridge *bridge);
>>>> -
>>>> +struct pci_host_bridge *pci_create_host_bridge(
>>>> +               struct device *parent, u32 db, struct pci_ops *ops,
>>>> +               void *sys, struct list_head *resources);
>>>>  /*
>>>>   * The first PCI_BRIDGE_RESOURCE_NUM PCI bus resources (those that correspond
>>>>   * to P2P or CardBus bridge windows) go in a table.  Additional ones (for
>>>> @@ -770,6 +777,8 @@ void pci_bus_add_devices(const struct pci_bus *bus);
>>>>  struct pci_bus *pci_create_root_bus(struct device *parent, u32 bus,
>>>>                                     struct pci_ops *ops, void *sysdata,
>>>>                                     struct list_head *resources);
>>>> +struct pci_bus *__pci_create_root_bus(struct pci_host_bridge *host);
>>>> +void pci_free_host_bridge(struct pci_host_bridge *host);
>>>>  int pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
>>>>  int pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
>>>>  void pci_bus_release_busn_res(struct pci_bus *b);
>>>> --
>>>> 1.7.1
>>>>
>>>> --
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>>>>
>>>
>>
>>
>> --
>> Thanks!
>> Yijing
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>> the body of a message to [email-masked]
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>>
> 

-- 
Thanks!
Yijing