Re: [PATCH v3 2/2] asm-generic: Add new pci.h and use it

Stafford Horne
2022-07-21T22:05:40Z

On Tue, Jul 19, 2022 at 08:58:39AM -0700, Palmer Dabbelt wrote:
> On Sun, 17 Jul 2022 17:41:14 PDT (-0700), shorne@gmail.com wrote:
> > The asm/pci.h used for many newer architectures share similar
> > definitions. Move the common parts to asm-generic/pci.h to allow for
> > sharing code.
> >
> > Two things to note are:
> >
> > - isa_dma_bridge_buggy, traditionally this is defined in asm/dma.h but
> > these architectures avoid creating that file and add the definition
> > to asm/pci.h.
> > - ARCH_GENERIC_PCI_MMAP_RESOURCE, csky does not define this so we
> > undefine it after including asm-generic/pci.h. Why doesn't csky
> > define it?
> > - pci_get_legacy_ide_irq, This function is only used on architectures
> > that support PNP. It is only maintained for arm64, in other
> > architectures it is removed.
> >
> > Suggested-by: Arnd Bergmann <arnd@arndb.de>
> > Link: https://lore.kernel.org/lkml/CAK8P3a0JmPeczfmMBE__vn=Jbvf=nkbpVaZCycyv40pZNCJJXQ@mail.gmail.com/
> > Signed-off-by: Stafford Horne <shorne@gmail.com>
> > ---
> > Second note on isa_dma_bridge_buggy, this is set on x86 but it it also set in
> > pci/quirks.c. We discussed limiting it only to x86 though as its a general
> > quick triggered by pci ids I think it will be more tricky than we thought so I
> > will leave as is. It might be nice to move it out of asm/dma.h and into
> > asm/pci.h though.
> >
> > Since v2:
> > - Nothing
> > Since v1:
> > - Remove definition of pci_get_legacy_ide_irq
> >
> > arch/arm64/include/asm/pci.h | 12 +++---------
> > arch/csky/include/asm/pci.h | 24 ++++--------------------
> > arch/riscv/include/asm/pci.h | 25 +++----------------------
> > arch/um/include/asm/pci.h | 24 ++----------------------
> > include/asm-generic/pci.h | 36 ++++++++++++++++++++++++++++++++++++
> > 5 files changed, 48 insertions(+), 73 deletions(-)
> > create mode 100644 include/asm-generic/pci.h
> >
> > diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
> > index b33ca260e3c9..1180e83712f5 100644
> > --- a/arch/arm64/include/asm/pci.h
> > +++ b/arch/arm64/include/asm/pci.h
> > @@ -9,7 +9,6 @@
> > #include <asm/io.h>
> >
> > #define PCIBIOS_MIN_IO 0x1000
> > -#define PCIBIOS_MIN_MEM 0
> >
> > /*
> > * Set to 1 if the kernel should re-assign all PCI bus numbers
> > @@ -18,9 +17,6 @@
> > (pci_has_flag(PCI_REASSIGN_ALL_BUS))
> >
> > #define arch_can_pci_mmap_wc() 1
> > -#define ARCH_GENERIC_PCI_MMAP_RESOURCE 1
> > -
> > -extern int isa_dma_bridge_buggy;
> >
> > #ifdef CONFIG_PCI
> > static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
> > @@ -28,11 +24,9 @@ static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
> > /* no legacy IRQ on arm64 */
> > return -ENODEV;
> > }
> > -
> > -static inline int pci_proc_domain(struct pci_bus *bus)
> > -{
> > - return 1;
> > -}
> > #endif /* CONFIG_PCI */
> >
> > +/* Generic PCI */
> > +#include <asm-generic/pci.h>
> > +
> > #endif /* __ASM_PCI_H */
> > diff --git a/arch/csky/include/asm/pci.h b/arch/csky/include/asm/pci.h
> > index ebc765b1f78b..44866c1ad461 100644
> > --- a/arch/csky/include/asm/pci.h
> > +++ b/arch/csky/include/asm/pci.h
> > @@ -9,26 +9,10 @@
> >
> > #include <asm/io.h>
> >
> > -#define PCIBIOS_MIN_IO 0
> > -#define PCIBIOS_MIN_MEM 0
> > +/* Generic PCI */
> > +#include <asm-generic/pci.h>
> >
> > -/* C-SKY shim does not initialize PCI bus */
> > -#define pcibios_assign_all_busses() 1
> > -
> > -extern int isa_dma_bridge_buggy;
> > -
> > -#ifdef CONFIG_PCI
> > -static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
> > -{
> > - /* no legacy IRQ on csky */
> > - return -ENODEV;
> > -}
> > -
> > -static inline int pci_proc_domain(struct pci_bus *bus)
> > -{
> > - /* always show the domain in /proc */
> > - return 1;
> > -}
> > -#endif /* CONFIG_PCI */
> > +/* csky doesn't use generic pci resource mapping */
> > +#undef ARCH_GENERIC_PCI_MMAP_RESOURCE
> >
> > #endif /* __ASM_CSKY_PCI_H */
> > diff --git a/arch/riscv/include/asm/pci.h b/arch/riscv/include/asm/pci.h
> > index 7fd52a30e605..12ce8150cfb0 100644
> > --- a/arch/riscv/include/asm/pci.h
> > +++ b/arch/riscv/include/asm/pci.h
> > @@ -12,29 +12,7 @@
> >
> > #include <asm/io.h>
> >
> > -#define PCIBIOS_MIN_IO 0
> > -#define PCIBIOS_MIN_MEM 0
>
> My for-next changes these in bb356ddb78b2 ("RISC-V: PCI: Avoid handing out
> address 0 to devices"). Do you mind either splitting out the arch/riscv
> bits or having this in via some sort of shared tag?

Hi Palmer,

I replied last on my phone but since it produces HTML multi-part email it got
rejected from a few places and I am not sure if you saw my reply.

It might be a bit hard to separate out the architecture specific bits as it
requires a bit of coordination with the asm-generic/pci.h move.

Some options:
1 I can produce a tag for you to merge into your for-next.
2 I can skip touching riscv at all in this patch and you can take care of it
in a future patch.
3 I could cherry pick your change bb356ddb78b2 ("RISC-V: PCI: Avoid handing out
address 0 to devices") to my for-next branch. It should help avoid conflict.

Seeing that I am still doing small updates here and there I am not sure when I
will be ablt to create a stable tag. So maybe 3 would work best?

-Stafford