Re: [RFC PATCH 08/16] PCI: Introduce pci_scan_host_bridge() and pci_host_info

[Liviu Dudau]

On Wed, Nov 19, 2014 at 02:09:12AM +0000, Yijing Wang wrote:
> >>  struct pci_host_bridge *pci_create_host_bridge(
> >> -		struct device *parent, u32 db, 
> >> -		struct pci_ops *ops, void *sysdata, 
> >> -		struct list_head *resources)
> >> +		struct device *parent, u32 db, struct pci_ops *ops, 
> >> +		struct pci_host_info *info)
> >>  {
> >>  	int error;
> >>  	struct pci_bus *b;
> >>  	struct pci_host_bridge *host, *h;
> >> -	struct pci_host_bridge_window *window, *n;
> >>  
> >>  	down_read(&pci_host_bridge_sem);
> >>  	list_for_each_entry(h, &pci_host_bridge_list, list) {
> >> @@ -53,7 +51,7 @@ struct pci_host_bridge *pci_create_host_bridge(
> >>  	if (!host)
> >>  		return NULL;
> >>  
> >> -	host->sysdata = sysdata;
> >> +	host->sysdata = info->arg;
> >>  	host->busnum = PCI_BUSNUM(db);
> >>  	host->domain = PCI_DOMAIN(db);
> >>  	host->ops = ops;
> >> @@ -63,18 +61,23 @@ struct pci_host_bridge *pci_create_host_bridge(
> >>  
> >>  	/* this is hack, just for build, will be removed later*/
> > 
> > Why do you need this hack? Just for calling pci_domain_nr() ?
> 
> Yes, it's temporary code, we need domain number here for pci host bridge register.
> 
> > 
> >>  	b = kzalloc(sizeof(*b), GFP_KERNEL);
> >> -	b->sysdata = sysdata;
> >> +	b->sysdata = host->sysdata;
> >>  	pci_bus_assign_domain_nr(b, parent);
> >>  	host->domain = pci_domain_nr(b);
> >> +	kfree(b);
> >>  
> ...
> >> +static int pci_default_init_res(struct pci_host_bridge *host,
> >> +		struct pci_host_info *info)
> >> +{
> >> +	struct pci_host_bridge_window *window, *n;
> >> +
> >> +	if (info->res_type != PCI_HOST_RES_DEFAULT) 
> >> +		list_for_each_entry_safe(window, n, info->resources,
> >> +				list)
> >> +			list_move_tail(&window->list, &host->windows);
> >> +	else
> >> +		info->res_type = PCI_HOST_RES_DEFAULT;
> > 
> > I'm confused about this assignment. Isn't this a nop as the else part
> > means info->res_type *is* PCI_HOST_RES_DEFAULT?
> 
> No, in this patch, host drivers pass a pci host bridge resources init hook
> in pci_host_info *info, and we call this info->init_res() in pci_create_host_bridge().
> 
> +struct pci_host_info {
> +	u8 res_type;
> +	void *arg;
> +	struct list_head *resources; /*just for build, will clean up later */
> +	int (*init_res)(struct pci_host_bridge *host,
> +			struct pci_host_info *info);
> +};
> +

That's not what I've asked! Your code does:

	if (info->res_type != PCI_HOST_RES_DEFAULT)
		....
	else /* info->res_type == PCI_HOST_RES_DEFAULT)
		info->res_type = PCI_HOST_RES_DEFAULT;

info->res_type is already == PCI_HOST_RES_DEFAULT in the else side, assignment is a NOP?


> 
> > 
> >> +
> >> +	return 0;
> >> +}
> ...
> >> @@ -2038,8 +2057,13 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
> >>  	bool found = false;
> >>  	struct pci_host_bridge *host;
> >>  	int max;
> >> +	struct pci_host_info info;
> >> +	
> >> +	info.arg = sysdata;
> >> +	info.resources = resources;
> >> +	info.init_res = pci_default_init_res;
> > 
> > I have mixed feelings about this patch. While it is heading in the right direction
> > of moving pci_host_bridge relevant information towards the right user, I don't think
> > you picked up the right set to move. The resource list is going to be copied into
> > internal pci_host_bridge list anyway, keeping another copy is not helpful *and*
> > you have increased the code size.
> > 
> > I think for now we should aim to get the *missing* data into pci_host_bridge: MSI
> > controllers and PCI domain/segment. Then we can do more cleanup.
> 
> Hi Liviu, I agree with you here, the changes to resources stuff seems not a perfect
> solution. In my patch 6, we could pass pci domain nr by u32 PCI_DOMBUS(domain, bus) argument,
> and store it in pci_host_bridge. For msi controller, we couldn't save the msi_controller
> in pci_host_bridge. Before we assume one pci host bridge only had one msi_controller,
> but now something changes, Jiang introduce hierarchy irq domain in x86, and now
> one pci host bridge may has more than one msi_controller. So I prefer to add a
> function to pci_host_bridge something like
> 
> struct msi_controller *pci_get_msi_controller(struct pci_dev *dev)

Yes, good idea.

> 
> > 
> >>  
> >> -	host = pci_create_host_bridge(parent, db, ops, sysdata, resources);
> >> +	host = pci_create_host_bridge(parent, db, ops, &info);
> >>  	if (!host)
> >>  		return NULL;
> >>  
> >> @@ -2070,6 +2094,47 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, u32 db,
> >>  }
> >>  EXPORT_SYMBOL(pci_scan_root_bus);
> >>  
> >> +struct pci_host_bridge *pci_scan_host_bridge(
> >> +		struct device *parent, u32 db, struct pci_ops *ops,
> >> +		struct pci_host_info *info)
> >> +{
> >> +	struct pci_host_bridge_window *window;
> >> +	bool found = false;
> >> +	struct pci_host_bridge *host;
> >> +	int max;
> >> +
> >> +	host = pci_create_host_bridge(parent, db, ops, info);
> >> +	if (!host)
> >> +		return NULL;
> >> +
> >> +	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(&host->bus->dev,
> >> +		 "No busn resource found for root bus, will use [bus %02x-ff]\n",
> >> +			host->busnum);
> >> +		pci_bus_insert_busn_res(host->bus, host->busnum, 255);
> >> +	}
> >> +
> >> +	max = pci_scan_child_bus(host->bus);
> >> +	if (!found)
> >> +		pci_bus_update_busn_res_end(host->bus, max);
> >> +
> >> +	return host;
> >> +
> >> +}
> >> +EXPORT_SYMBOL(pci_scan_host_bridge);
> >> +
> >>  /**
> >>   * pci_rescan_bus_bridge_resize - scan a PCI bus for devices.
> >>   * @bridge: PCI bridge for the bus to scan
> >> diff --git a/include/linux/pci.h b/include/linux/pci.h
> >> index daa7f40..a51f5f5 100644
> >> --- a/include/linux/pci.h
> >> +++ b/include/linux/pci.h
> >> @@ -412,6 +412,21 @@ struct pci_host_bridge {
> >>  	void *release_data;
> >>  };
> >>  
> >> +struct pci_host_info {
> >> +	u8 res_type;
> >> +	void *arg;
> >> +	struct list_head *resources; /*just for build, will clean up later */
> >> +	int (*init_res)(struct pci_host_bridge *host, 
> >> +			struct pci_host_info *info);
> >> +};
> >> +
> >> +static inline void init_pci_host_info(struct pci_host_info *info)
> >> +{
> >> +	memset(info, 0 , sizeof(*info));
> >> +}
> > 
> > Where is this used?
> 
> Host driver uses it to init pci_host_info.

Might be worth adding it that patch rather than here.

Best regards,
Liviu

> 
> > 
> >> +
> >> +#define PCI_HOST_RES_DEFAULT	0x2
> >> +
> > 
> > Magic number?
> 
> Hmmm, I will rework pci host bridge resources stuff.
> 
> > 
> > Best regards,
> > Liviu
> > 
> >>  #define	to_pci_host_bridge(n) container_of(n, struct pci_host_bridge, dev)
> >>  void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
> >>  		     void (*release_fn)(struct pci_host_bridge *),
> >> @@ -420,7 +435,7 @@ void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
> >>  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);
> >> +		struct pci_host_info *info);
> >>  /*
> >>   * 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
> >> @@ -785,6 +800,9 @@ void pci_bus_release_busn_res(struct pci_bus *b);
> >>  struct pci_bus *pci_scan_root_bus(struct device *parent, u32 bus,
> >>  					     struct pci_ops *ops, void *sysdata,
> >>  					     struct list_head *resources);
> >> +struct pci_host_bridge *pci_scan_host_bridge(struct device *parent,
> >> +		u32 db, struct pci_ops *ops,
> >> +		struct pci_host_info *info);
> >>  struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
> >>  				int busnr);
> >>  void pcie_update_link_speed(struct pci_bus *bus, u16 link_status);
> >> -- 
> >> 1.7.1
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> >> the body of a message to majordomo@xxxxxxxxxxxxxxx
> >> 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 majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    Â\_(ã)_/Â

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/