From mboxrd@z Thu Jan  1 00:00:00 1970
From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: Re: [PATCH v10 00/10] Support for creating generic PCI host bridges
 from DT
Date: Fri, 12 Sep 2014 03:25:13 -0500
Message-ID: <5412ADE9.2050708@amd.com>
References: <1410184472-17630-1-git-send-email-Liviu.Dudau@arm.com>
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To: Liviu Dudau <Liviu.Dudau@arm.com>, Bjorn Helgaas <bhelgaas@google.com>, Arnd Bergmann <arnd@arndb.de>, Rob Herring <robh+dt@kernel.org>, Jason Gunthorpe <jgunthorpe@obsidianresearch.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <Will.Deacon@arm.com>, Russell King <linux@arm.linux.org.uk>, linux-pci <linux-pci@vger.kernel.org>, Linus Walleij <linus.walleij@linaro.org>
Cc: Tanmay Inamdar <tinamdar@apm.com>, Grant Likely <grant.likely@secretlab.ca>, Sinan Kaya <okaya@codeaurora.org>, Jingoo Han <jg1.han@samsung.com>, Kukjin Kim <kgene.kim@samsung.com>, linux-arch <linux-arch@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, Device Tree ML <devicetree@vger.kernel.org>, LAKML <linux-arm-kernel@lists.infradead.org>
List-Id: devicetree@vger.kernel.org

On 9/8/2014 8:54 AM, Liviu Dudau wrote:
> This is my version 10 of the attempt at adding support for generic PCI host
> bridge controllers that make use of device tree information to
> configure themselves. This version reverses v9's attempt to create one function
> to drive the whole process of extracting the host bridge ranges, setup the
> host bridge driver and then scan the root bus behind the host bridge. While it
> would've been quite user friendly, I agree that it would've caused a lot of pain
> in the future.
>
> I would like to get ACKs for the remaining patches as I would like to integrate
> this into -next in the following week.
>
> This version marks an implementation break with the previous versions as
> of_create_pci_host_bridge() is now gone. It gets replaced by
> of_pci_get_host_bridge_resources() that only parses the DT and extracts the
> relevant ranges and converts them to resources. The updated host bridge drivers
> will have to follow the guidelines in this example code:
>
> static int foohb_probe(struct platform_device *pdev)
> {
> 	struct device_node *dn = pdev->dev.of_node;
> 	struct foohb_drv *drv;
> 	resource_size_t io_base = 0;  /* phys address for start of IO */
> 	struct pci_bus *bus;
> 	int err = 0;
> 	LIST_HEAD(res);
>
> 	.....
> 	err = of_pci_get_host_bridge_resources(dn, 0, 255, &res, &io_base);
> 	if (err)
> 		goto err_handling;
> 	err = foohb_setup(drv, ...., &res, &io_base);
> 	if (err)
> 		goto err_handling;

My understanding is that the "foohb_setup" above is supposed to be equivalent
to the "int (*setup)(struct pci_host_bridge *, resource_size_t)" in V9 that was
passed in as an argument of "of_create_pci_hot_bridge()".

The problem I have is I need an intermediate step between "pci_create_root_bus()"
and "pci_scan_child_bus()" in order to update the information such as the "pci_bus->msi"
before this is propagate down to the child bus during the "pci_scan_child_bus"
which is also called in the pci_scan_root_bus() function.

Does this mean that I should not be calling the pci_scan_root_bus(), and tries to
re-implement the same logic in my driver?

Thanks,

Suravee

> 	.....
> 	pci_add_flags(....);
> 	bus = pci_scan_root_bus(&pdev->dev, 0, &foohb_ops, drv, &res);
> 	if (!bus)
> 		goto err_handling;
> 	....
> 	return 0;
>
> err_handling:
> 	......
> 	return err;
> }
>