Re: [RFC PATCH 2/2] arm: pcibios: move to generic PCI domains

[Jingoo Han <jg1.han@samsung.com>]

On Monday, November 03, 2014 8:34 PM, Lucas Stach wrote:
> Am Montag, den 03.11.2014, 11:23 +0000 schrieb Lorenzo Pieralisi:
> > On Mon, Nov 03, 2014 at 01:18:12AM +0000, Jingoo Han wrote:
> > > On Thursday, October 30, 2014 8:45 PM, Lorenzo Pieralisi wrote:
> > > >
> > > > Most if not all ARM PCI host controller device drivers either ignore the
> > > > domain field in the pci_sys_data structure or just increment it every
> > > > time a host controller is probed, using it as a domain counter.
> > > >
> > > > Therefore, instead of relying on pci_sys_data to stash the domain number
> > > > in a standard location, ARM pcibios code can be moved to the newly
> > > > introduced generic PCI domains code, implemented in commits:
> > > >
> > > > commit 41e5c0f81d3e676d671d96a0a1fafb27abfbd9
> > > > ("of/pci: Add pci_get_new_domain_nr() and of_get_pci_domain_nr()")
> > > >
> > > > commit 670ba0c8883b576d0aec28bd7a838358a4be1
> > > > ("PCI: Add generic domain handling")
> > > >
> > > > In order to assign a domain number dynamically, the ARM pcibios defines
> > > > the function, called by core PCI code:
> > > >
> > > > void pci_bus_assign_domain_nr(...)
> > > >
> > > > that relies on a DT property to define the domain number or falls back to
> > > > a counter; its usage replaces the current domain assignment code in PCI
> > > > host controllers present in the kernel.
> > > >
> > > > Cc: Arnd Bergmann <arnd@arndb.de>
> > > > Cc: Phil Edworthy <phil.edworthy@renesas.com>
> > > > Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
> > > > Cc: Jingoo Han <jg1.han@samsung.com>
> > > > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > > > Cc: Russell King <linux@arm.linux.org.uk>
> > > > Cc: Mohit Kumar <mohit.kumar@st.com>
> > > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > >
> > > (+CC Richard Zhu, Lucas Stach, Kishon Vijay Abraham I, Murali Karicheri)
> > >
> > > Acked-by: Jingoo Han <jg1.han@samsung.com>
> >
> > Thank you Jingoo.
> >
> > > For a long time, I have wanted the patch like this. Personally,
> > > I want to increase the build coverage and keep the same binary
> > > regardless of config options as possible; thus, I don't like
> > > #ifdef guards such as '#ifdef CONFIG_PCI_DOMAINS'. When I submitted
> > > the first patch for 'pcie-designware.c', I was not able to find
> > > a way to remove '#ifdef CONFIG_PCI_DOMAINS' from 'pcie-designware.c'.
> > >
> > > This patch looks good and I think that this patch will not make
> > > the problem. However, I didn't test this patch with Exynos platform,
> > > due to some reasons. So, I hope that other engineers test this patch
> > > on other SoC platforms related to designware PCIe.
> > >
> > > To Mohit Kumar (ST SPEAR13XX), Richard Zhu/Lucas Stach (IMX6)
> > >     Kishon Vijay Abraham I (TI DRA7XX), Murali Karicheri (TI KEYSTONE)
> > >
> > > Would you test this patch and share the result?
> > > It would be very helpful. Thank you.
> >
> > I am happy to wait for a week or two before asking to add this code to -next,
> > it would be definitely great to get more coverage on pcie-designware.
> >
> I've just tested this on i.MX6 on top of 3.18-rc3. Given that we only
> use a single domain there this patch should obviously not break
> anything. Testing backs this claim, so:
> 
> Tested-by: Lucas Stach <l.stach@pengutronix.de>

Thank you for your testing!
In fact, Exynos uses multi domain structures.

> 
> I also looked through the patch briefly and it seems sane to me, so this
> is also:
> 
> Acked-by: Lucas Stach <l.stach@pengutronix.de>
> 
> I don't like the fact that a proper binding documentation is missing for
> the "linux,pci-domain" property, but this isn't the fault of this
> patchset.

I agree with your opinion. I also thought that the binding documentation
for the "linux,pci-domain" property is needed.

> 
> Regards,
> Lucas
> 
> --
> Pengutronix e.K.             | Lucas Stach                 |
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