Messages in this thread |  | | Date | Fri, 22 Jul 2022 08:27:31 -0700 (PDT) | Subject | Re: [PATCH v3 2/2] asm-generic: Add new pci.h and use it | From | Palmer Dabbelt <> |
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On Thu, 21 Jul 2022 16:06:52 PDT (-0700), Rob Herring wrote: > On Tue, Jul 19, 2022 at 9:59 AM Palmer Dabbelt <palmer@dabbelt.com> 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? > > Shouldn't the values not matter here if the IO and mem resources are > described in the DT (and don't use 0)? The values of 4 and 16 look > odd.
The linked thread has a fairly long discussion <https://lore.kernel.org/all/alpine.DEB.2.21.2202260044180.25061@angie.orcam.me.uk/>. I agree it's odd to have this in arch code: "don't hand out address 0" isn't really a RISC-V constraint (ie, we don't have architecture-defined limitations on these address spaces) but a constraint that comes from the generic port I/O functions and some other related PCI/resource code where the value 0 is a sentinel.
Maybe the right thing to do here is actually to make the default definitions of these macros non-zero, or to add some sort of ARCH_ flavor of them and move that non-zero requirement closer to where it comes from? From the look of it any port that uses the generic port I/O functions and has 0 for these will be broken in the same way.
That said, I'm not really a PCI guy so maybe Bjorn or Maciej has a better idea?
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