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

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Message-ID: <YtnNrkH9UJYreU5M@antec>
Date:   Fri, 22 Jul 2022 07:05:34 +0900
From:   Stafford Horne <shorne@...il.com>
To:     Palmer Dabbelt <palmer@...belt.com>
Cc:     linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        catalin.marinas@....com, Will Deacon <will@...nel.org>,
        guoren@...nel.org, Paul Walmsley <paul.walmsley@...ive.com>,
        aou@...s.berkeley.edu, richard@....at,
        anton.ivanov@...bridgegreys.com, johannes@...solutions.net,
        bhelgaas@...gle.com, linux-arm-kernel@...ts.infradead.org,
        linux-csky@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-um@...ts.infradead.org, linux-pci@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: Re: [PATCH v3 2/2] asm-generic: Add new pci.h and use it

On Tue, Jul 19, 2022 at 08:58:39AM -0700, Palmer Dabbelt wrote:
> On Sun, 17 Jul 2022 17:41:14 PDT (-0700), shorne@...il.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@...db.de>
> > Link: https://lore.kernel.org/lkml/CAK8P3a0JmPeczfmMBE__vn=Jbvf=nkbpVaZCycyv40pZNCJJXQ@mail.gmail.com/
> > Signed-off-by: Stafford Horne <shorne@...il.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