linux-kernel - Re: [RFC 2/4] PCI: generic: Add support for ARM64 and MSI(x)

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Message-ID: <20141001084626.GZ841@e106497-lin.cambridge.arm.com>
Date:	Wed, 1 Oct 2014 09:46:26 +0100
From:	Liviu Dudau <Liviu.Dudau@....com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Mark Rutland <Mark.Rutland@....com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	Marc Zyngier <Marc.Zyngier@....com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Will Deacon <Will.Deacon@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>
Subject: Re: [RFC 2/4] PCI: generic: Add support for ARM64 and MSI(x)

On Tue, Sep 30, 2014 at 09:01:14PM +0100, Arnd Bergmann wrote:
> On Tuesday 30 September 2014 20:54:41 Arnd Bergmann wrote:
> > On Tuesday 30 September 2014 18:48:21 Liviu Dudau wrote:
> > > > > > > These are the functions I found that refer to pci_sys_data on arm32:
> > > > > > > 
> > > > > > > pcibios_add_bus
> > > > > > > pcibios_remove_bus
> > > 
> > > These are only needed if you want to do per HB processing of the bus
> > > 
> > > > > > > pcibios_align_resource
> > > 
> > > mvebu is the only user of this function.
> > > 
> > > > > > > pci_mmap_page_range
> > > 
> > > This is only needed when mapping a PCI resource to userspace. Is that your case here?
> > > 
> > > > > > > pci_domain_nr
> > > > > > > pci_proc_domain
> > > 
> > > We have equivalent functionality in the generic patches for those.
> > > 
> > 
> > We clearly don't need those functions for the new drivers, but that's not
> > the point. The problem is that when you build a kernel that has both
> > a traditional host bridge driver and a new one in it, you always get those
> > functions and they get called from the PCI core, with incorrect arguments.
> 
> FWIW, the last time we discussed this, I think I had suggested that the
> functions that are currently architecture specific and have a generic
> __weak fallback could become function pointers in a per-host structure
> passed to pci_scan_root_bus, either a new structure or an extended
> struct pci_ops. Something along these lines:

Agree to the general idea. But have a look why host drivers need the add_bus ops:
to add MSI information into the bus!! If we take care of the MSI in the generic
code there is less of a need for this function at all.

Best regards,
Liviu

> 
> diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
> index 7fc42784becb..3da32fc631d0 100644
> --- a/arch/arm/include/asm/mach/pci.h
> +++ b/arch/arm/include/asm/mach/pci.h
> @@ -36,7 +36,6 @@ struct hw_pci {
>  					  resource_size_t start,
>  					  resource_size_t size,
>  					  resource_size_t align);
> -	void		(*add_bus)(struct pci_bus *bus);
>  	void		(*remove_bus)(struct pci_bus *bus);
>  };
>  
> @@ -65,7 +64,6 @@ struct pci_sys_data {
>  					  resource_size_t start,
>  					  resource_size_t size,
>  					  resource_size_t align);
> -	void		(*add_bus)(struct pci_bus *bus);
>  	void		(*remove_bus)(struct pci_bus *bus);
>  	void		*private_data;	/* platform controller private data	*/
>  };
> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
> index 17a26c17f7f5..3cbcf8dc41e4 100644
> --- a/arch/arm/kernel/bios32.c
> +++ b/arch/arm/kernel/bios32.c
> @@ -360,13 +360,6 @@ void pcibios_fixup_bus(struct pci_bus *bus)
>  }
>  EXPORT_SYMBOL(pcibios_fixup_bus);
>  
> -void pcibios_add_bus(struct pci_bus *bus)
> -{
> -	struct pci_sys_data *sys = bus->sysdata;
> -	if (sys->add_bus)
> -		sys->add_bus(bus);
> -}
> -
>  void pcibios_remove_bus(struct pci_bus *bus)
>  {
>  	struct pci_sys_data *sys = bus->sysdata;
> @@ -475,7 +468,6 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
>  		sys->swizzle = hw->swizzle;
>  		sys->map_irq = hw->map_irq;
>  		sys->align_resource = hw->align_resource;
> -		sys->add_bus = hw->add_bus;
>  		sys->remove_bus = hw->remove_bus;
>  		INIT_LIST_HEAD(&sys->resources);
>  
> diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
> index b1315e197ffb..c9a0ee0429e8 100644
> --- a/drivers/pci/host/pci-mvebu.c
> +++ b/drivers/pci/host/pci-mvebu.c
> @@ -716,6 +716,7 @@ static int mvebu_pcie_rd_conf(struct pci_bus *bus, u32 devfn, int where,
>  static struct pci_ops mvebu_pcie_ops = {
>  	.read = mvebu_pcie_rd_conf,
>  	.write = mvebu_pcie_wr_conf,
> +	.add_bus = mvebu_pcie_add_bus,
>  };
>  
>  static int mvebu_pcie_setup(int nr, struct pci_sys_data *sys)
> @@ -823,7 +824,6 @@ static void mvebu_pcie_enable(struct mvebu_pcie *pcie)
>  	hw.map_irq        = of_irq_parse_and_map_pci;
>  	hw.ops            = &mvebu_pcie_ops;
>  	hw.align_resource = mvebu_pcie_align_resource;
> -	hw.add_bus        = mvebu_pcie_add_bus;
>  
>  	pci_common_init(&hw);
>  }
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index a63a47a70846..be6d56358320 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1885,6 +1885,8 @@ int __weak pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
>  
>  void __weak pcibios_add_bus(struct pci_bus *bus)
>  {
> +	if (bus->ops && bus->ops->add_bus)
> +		bus->ops->add_bus(bus);		
>  }
>  
>  void __weak pcibios_remove_bus(struct pci_bus *bus)
> 
> 	Arnd
> 
> 

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

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