Re: [RFC/RFT PATCH 05/18] ARM: PCI: dove: Convert PCI scan API to pci_scan_root_bus_bridge()

From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Lunn <andrew@lunn.ch>,
	Pratyush Anand <pratyush.anand@gmail.com>,
	Gabriele Paoloni <gabriele.paoloni@huawei.com>,
	linux-pci <linux-pci@vger.kernel.org>,
	Shawn Lin <shawn.lin@rock-chips.com>,
	Will Deacon <will.deacon@arm.com>,
	Michal Simek <michal.simek@xilinx.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Tanmay Inamdar <tinamdar@apm.com>,
	Matthew Minter <matt@masarand.com>, Rob Herring <robh@kernel.org>,
	Joao Pinto <Joao.Pinto@synopsys.com>,
	Wenrui Li <wenrui.li@rock-chips.com>,
	Russell King <linux@armlinux.org.uk>,
	Murali Karicheri <m-karicheri2@ti.com>,
	Jason Cooper <jason@lakedaemon.net>,
	Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>,
	Simon Horman <horms@verge.net.au>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Mingkai Hu <mingkai.hu@freescale.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
	Jingoo Han <jingoohan1@gmail.com>,
	Stanimir Varbanov <svarbanov@mm-sol.com>,
	Minghuan Lian <minghuan.Lian@freescale.com>,
	Zhou Wang <wangzhou1@hisilicon.com>,
	Roy Zang <tie-fei.zang@freescale.com>
Subject: Re: [RFC/RFT PATCH 05/18] ARM: PCI: dove: Convert PCI scan API to pci_scan_root_bus_bridge()
Date: Wed, 3 May 2017 11:31:53 +0100	[thread overview]
Message-ID: <20170503103153.GB10800@red-moon> (raw)
In-Reply-To: <CAK8P3a1bnnq-9iuse43bCNX_9TirZPOtmH_vFsvJ9VOAsoUBzQ@mail.gmail.com>

On Fri, Apr 28, 2017 at 02:38:48PM +0200, Arnd Bergmann wrote:
> On Wed, Apr 26, 2017 at 1:17 PM, Lorenzo Pieralisi
> <lorenzo.pieralisi@arm.com> wrote:
> > The introduction of pci_scan_root_bus_bridge() provides a PCI core
> > API to scan a PCI root bus backed by an already initialized
> > struct pci_host_bridge object, which simplifies the bus scan
> > interface and makes the PCI scan root bus interface easier to
> > generalize as members are added to the struct pci_host_bridge().
> >
> > Convert ARM dove platform code to pci_scan_root_bus_bridge() to improve
> > the PCI root bus scanning interface.
> >
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> 
> Is this patch required for one of the later steps in the series?
> 
> As non-DT dove uses the traditional pci_common_init() helper rather
> than registering its own driver, I wonder if there is anything to gain here.

Well, the point is, the non-DT platforms I patched implement a custom
.scan method in struct hw_pci. If we move the bridge allocation to
pcibios_init_hw() we would end up initializing some struct
pci_host_bridge fields in pcibios_init_hw() and some in the custom .scan
method (ie custom pci_ops) which I found not very elegant but it could be
done I reckon, I need to give it a go to see how the code looks like.

Lorenzo

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