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

From: Yijing Wang <[email-masked]>
Date: Fri, 21 Nov 2014 10:53:01 +0800

>>> 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().
> 
> That's fine, but the function signature doesn't change, right? And I think we should keep
> pci_scan_root_bus() with the current signature as well (except change sysdata into a
> struct pci_host_bridge *). We create the host bridge in one step, stuff it with all the
> data that we need for scanning the root and associated busses, and then call pci_scan_root_bus().
> pci_host_bridge has the ops from pci_create_host_bridge() and the root bus from pci_scan_root_bus().

Liviu, could you have some draft patches about replace sysdata with pci_host_bridge, so we could
discuss the details base it. :)

> 
> Hope this makes sense.
> 
>>
>>
>>>>>> -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 ? 
> 
> Of course we put pci_host_bridge init *calls* in the host drivers because we need to do host
> driver specific initialisation there anyway. 
> 
>> And if we still use arch spec
>> macros convert ssydata to pci_controller, so what's the greatest advantage ?
> 
> Agree, the macro is not useful unless we have a common pci_controller structure. Sorry about
> the noise.
> 
>>
>> If we move domain and msi_chip out of sysdata, what's other things in sysdata still need us
>> to convert in PCI core ?
> 
> I've never said we need to keep sysdata. From my discussion with Bjorn a year ago the idea was
> to put the sysdata members into pci_host_bridge structure and remove sysdata member from pci_bus.
> pci_scan_root_bus() can still get a parameter called sysdata if we want, but it will be a
> struct pci_host_bridge * type.

Fine.

> 
> Best regards,
> Liviu
> 
>>
>>
>>
>>>
>>> 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
>>>>>>
>>>>>> --
>>>>>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>>>>>> the body of a message to [email-masked]
>>>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Thanks!
>>>> Yijing
>>>>
>>>> --
>>>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>>>> the body of a message to [email-masked]
>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>
>>>
>>
>>
>> --
>> Thanks!
>> Yijing
>>
>>
> 

-- 
Thanks!
Yijing