Re: [RFC] Build with arm64 configuration

[Liviu Dudau <Liviu.Dudau@arm.com>]

On Wed, Mar 11, 2015 at 08:00:11AM +0000, Jaehoon Chung wrote:
> Dear, Bjorn.
> 
> On 03/10/2015 11:17 AM, Bjorn Helgaas wrote:
> > [+cc Jingoo, Mohit]
> > 
> > On Mon, Mar 9, 2015 at 8:36 PM, Jaehoon Chung <jh80.chung@samsung.com> wrote:
> >> Dear, Bjorn.
> >>
> >> Thanks for reply.
> >>
> >> On 03/10/2015 08:35 AM, Bjorn Helgaas wrote:
> >>> On Mon, Mar 9, 2015 at 7:18 AM, Jaehoon Chung <jh80.chung@samsung.com> wrote:
> >>>> Hi,
> >>>>
> >>>> I have a question for building arm64.
> >>>> (Actually, i didn't have many knowledges for PCIe.)
> >>>> When i built with arm64 configuration, then i always found the compiler errors.
> >>>
> >>> The kernel does build for arm64, so you'll have to be more specific
> >>> about the problem you're seeing.
> >>
> >> I built the pcie-designware.c and pci-exynos.c.
> >>
> >> When pcie-designware.c is built, i found the below error message.
> >> drivers/pci/host/pcie-designware.c:74:52: warning: Ëœstruct pci_sys_dataâ„¢ declared inside parameter list
> >>  static inline struct pcie_port *sys_to_pcie(struct pci_sys_data *sys)
> >>                                                     ^
> >> drivers/pci/host/pcie-designware.c:74:52: warning: its scope is only this definition or declaration, which is probably not what you want
> >> In file included from include/uapi/linux/stddef.h:1:0,
> >>                  from include/linux/stddef.h:4,
> >>                  from ./include/uapi/linux/posix_types.h:4,
> >>                  from include/uapi/linux/types.h:13,
> >>                  from include/linux/types.h:5,
> >>                  from include/linux/smp.h:10,
> >>                  from include/linux/irq.h:12,
> >>                  from drivers/pci/host/pcie-designware.c:14:
> >> drivers/pci/host/pcie-designware.c: In function Ëœsys_to_pcie":
> >> drivers/pci/host/pcie-designware.c:76:13: error: dereferencing pointer to incomplete type
> >>   BUG_ON(!sys->private_data);
> >>
> >> I found it's located at arch/arm/include/asm/mach/pci.h.
> >> It can't refer when do build for arm64.
> >> So I think that i missed something..I have also searched the patches relevant to this at patchwork.
> >> Some patch have copied header files relevant to "pci" to "arch/arm64/include/".
> >> (This is not solution.)
> >>
> >> And i don't want to add #ifdef CONFIG_ARM64 into pcie-designware.c
> >> I think mailing should know the graceful solution.
> >>
> >> If i can solve this problem, i will contribute for pci-exynos.c.
> > 
> > Oh, I think pcie-designware.c and pci-exynos.c currently only work on
> > arm, not on arm64.  I don't know enough about them to know whether
> > they could be made to work on arm64.  But Jingoo and Mohit probably
> > do.

Jaehoon,

pci-exynos and pcie-designware need to be converted to the generic PCIe framework and then
they will work on both arm and arm64. For an example of a driver that successfully works
in both worlds look at pci-versatile.c.

Currently, PCI host bridges that work on arch/arm depend on pci_sys_data, like you have
discovered. There is no reason to do that nowadays, and Lorenzo Pieralisi, Yijing Wang
and others are trying to get rid of that structure from arch/arm.

Best regards,
Liviu

> 
> I'm checking the code..
> If my understanding is right, pci_sys_data is just used to take data relevant to pice_port.
> So I think it can get from device-tree or other.
> I don't exactly know why needs "pci_sys_data".
> 
> It seems to discuss about pcie (struct pci_sys_data and hw_pci) on arm64 at mailing..right?
> ([RFC 2/4] PCI: generic: Add support for ARM64 and MSI(x))
> 
> If need to work, i have interesting for contributing pcie on arm64.(pcie-designware.c and pci-exynos.c)
> But i need to gain the knowledge of pcie..
> 
> Best Regards,
> Jaehoon Chung
> 
> > 
> > Bjorn
> > 
> 
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