[PATCH v2 2/2] asm-generic: Add new pci.h and use it

[PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

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>
---
 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
-
-/* RISC-V shim does not initialize PCI bus */
-#define pcibios_assign_all_busses() 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)
-{
-	/* no legacy IRQ on risc-v */
-	return -ENODEV;
-}
-
-static inline int pci_proc_domain(struct pci_bus *bus)
-{
-	/* always show the domain in /proc */
-	return 1;
-}
-
 #ifdef	CONFIG_NUMA
 
 static inline int pcibus_to_node(struct pci_bus *bus)
@@ -50,4 +28,7 @@ static inline int pcibus_to_node(struct pci_bus *bus)
 
 #endif  /* CONFIG_PCI */
 
+/* Generic PCI */
+#include <asm-generic/pci.h>
+
 #endif  /* _ASM_RISCV_PCI_H */
diff --git a/arch/um/include/asm/pci.h b/arch/um/include/asm/pci.h
index da13fd5519ef..34fe4921b5fa 100644
--- a/arch/um/include/asm/pci.h
+++ b/arch/um/include/asm/pci.h
@@ -4,28 +4,8 @@
 #include <linux/types.h>
 #include <asm/io.h>
 
-#define PCIBIOS_MIN_IO		0
-#define PCIBIOS_MIN_MEM		0
-
-#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 IRQs */
-	return -ENODEV;
-}
-#endif
-
-#ifdef CONFIG_PCI_DOMAINS
-static inline int pci_proc_domain(struct pci_bus *bus)
-{
-	/* always show the domain in /proc */
-	return 1;
-}
-#endif  /* CONFIG_PCI */
+/* Generic PCI */
+#include <asm-generic/pci.h>
 
 #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
 /*
diff --git a/include/asm-generic/pci.h b/include/asm-generic/pci.h
new file mode 100644
index 000000000000..fbc25741696a
--- /dev/null
+++ b/include/asm-generic/pci.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_GENERIC_PCI_H
+#define __ASM_GENERIC_PCI_H
+
+#include <linux/types.h>
+
+#ifndef PCIBIOS_MIN_IO
+#define PCIBIOS_MIN_IO		0
+#endif
+
+#ifndef PCIBIOS_MIN_MEM
+#define PCIBIOS_MIN_MEM		0
+#endif
+
+#ifndef pcibios_assign_all_busses
+/* For bootloaders that do not initialize the PCI bus */
+#define pcibios_assign_all_busses() 1
+#endif
+
+extern int isa_dma_bridge_buggy;
+
+/* Enable generic resource mapping code in drivers/pci/ */
+#define ARCH_GENERIC_PCI_MMAP_RESOURCE
+
+#ifdef CONFIG_PCI
+
+static inline int pci_proc_domain(struct pci_bus *bus)
+{
+	/* always show the domain in /proc */
+	return 1;
+}
+
+#endif /* CONFIG_PCI */
+
+#endif /* __ASM_GENERIC_PCI_H */
-- 
2.36.1


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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Christoph Hellwig]

On Sun, Jul 17, 2022 at 12:34:53PM +0900, Stafford Horne wrote:
> 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.

This doesn't have anyting to do with PCI support.  I think adding a
separate header just for this that always stubs it out unless a config
option is set (which x86 then selects) is the besy idea here.  I also
think the isa_dma_bridge_buggy needs to move out of the PCI code as
well.

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Arnd Bergmann]

On Mon, Jul 18, 2022 at 6:37 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Sun, Jul 17, 2022 at 12:34:53PM +0900, Stafford Horne wrote:
> > 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.
>
> This doesn't have anyting to do with PCI support.  I think adding a
> separate header just for this that always stubs it out unless a config
> option is set (which x86 then selects) is the besy idea here.  I also
> think the isa_dma_bridge_buggy needs to move out of the PCI code as
> well.

Most architectures have it in asm/dma.h, which is probably the right place
(if we end up keeping it), since this is for the ISA DMA API.

I would copy this declaration from x86

#ifdef CONFIG_PCI
extern int isa_dma_bridge_buggy;
#else
#define isa_dma_bridge_buggy (0)
#endif

to asm-generic/dma.h and remove it from arch/sh to avoid the
one duplicate definition. The architectures that have the declaration
in asm/pci.h (arm64, csky, riscv) already get the asm-generic version
of asm/dma.h.

As mentioned before, it would be even better to just remove it
entirely from everything except x86, and enclose the four
references in an explicit "#ifdef X86_32". The variable declaration
only exists because drivers/pci/quirks.c is compiled on all
architecture, but the individual quirk is only active  based on
the PCI device ID of certain early PCI-ISA bridges.

      Arnd

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Arnd Bergmann]

On Tue, Jul 19, 2022 at 1:19 AM Stafford Horne <shorne@gmail.com> wrote:
> On Mon, Jul 18, 2022, 3:56 PM Arnd Bergmann <arnd@arndb.de> wrote:
>>
>> As mentioned before, it would be even better to just remove it
>> entirely from everything except x86, and enclose the four
>> references in an explicit "#ifdef X86_32". The variable declaration
>> only exists because drivers/pci/quirks.c is compiled on all
>> architecture, but the individual quirk is only active  based on
>> the PCI device ID of certain early PCI-ISA bridges.
>
>
> Ok, I was thinking of that route but once I saw the pci device IDs I
> wasn't so sure it was limited to x86.  I'll go ahead with that approach.

Ok, thanks!

I checked all the PCI IDs yesterday, and I'm fairly sure they are x86
specific. While some related products are general-purpose PCI-ISA
bridges that have shown up on mips or arm boards, the ones listed
here should all be safe.

         Arnd

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

On Tue, Jul 19, 2022 at 09:45:58AM +0200, Arnd Bergmann wrote:
> On Tue, Jul 19, 2022 at 1:19 AM Stafford Horne <shorne@gmail.com> wrote:
> > On Mon, Jul 18, 2022, 3:56 PM Arnd Bergmann <arnd@arndb.de> wrote:
> >>
> >> As mentioned before, it would be even better to just remove it
> >> entirely from everything except x86, and enclose the four
> >> references in an explicit "#ifdef X86_32". The variable declaration
> >> only exists because drivers/pci/quirks.c is compiled on all
> >> architecture, but the individual quirk is only active  based on
> >> the PCI device ID of certain early PCI-ISA bridges.
> >
> >
> > Ok, I was thinking of that route but once I saw the pci device IDs I
> > wasn't so sure it was limited to x86.  I'll go ahead with that approach.
> 
> Ok, thanks!
> 
> I checked all the PCI IDs yesterday, and I'm fairly sure they are x86
> specific. While some related products are general-purpose PCI-ISA
> bridges that have shown up on mips or arm boards, the ones listed
> here should all be safe.

This is what I have now, I will add a similar patch between 1/2 and 2/2, if this
looks ok.

It adds a few ifdef's which might be controversial but I think it provides more
cleanup than added complexity.  I compile tested with x86_64, x86_32 and
OpenRISC.

diff --git a/arch/alpha/include/asm/dma.h b/arch/alpha/include/asm/dma.h
index 28610ea7786d..a04d76b96089 100644
--- a/arch/alpha/include/asm/dma.h
+++ b/arch/alpha/include/asm/dma.h
@@ -365,13 +365,4 @@ extern void free_dma(unsigned int dmanr);	/* release it again */
 #define KERNEL_HAVE_CHECK_DMA
 extern int check_dma(unsigned int dmanr);
 
-/* From PCI */
-
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy 	(0)
-#endif
-
-
 #endif /* _ASM_DMA_H */
diff --git a/arch/arc/include/asm/dma.h b/arch/arc/include/asm/dma.h
index 5b744f4b10a7..02431027ed2f 100644
--- a/arch/arc/include/asm/dma.h
+++ b/arch/arc/include/asm/dma.h
@@ -7,10 +7,5 @@
 #define ASM_ARC_DMA_H
 
 #define MAX_DMA_ADDRESS 0xC0000000
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	0
-#endif
 
 #endif
diff --git a/arch/arm/include/asm/dma.h b/arch/arm/include/asm/dma.h
index a81dda65c576..907d139be431 100644
--- a/arch/arm/include/asm/dma.h
+++ b/arch/arm/include/asm/dma.h
@@ -143,10 +143,4 @@ extern int  get_dma_residue(unsigned int chan);
 
 #endif /* CONFIG_ISA_DMA_API */
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy    (0)
-#endif
-
 #endif /* __ASM_ARM_DMA_H */
diff --git a/arch/ia64/include/asm/dma.h b/arch/ia64/include/asm/dma.h
index 59625e9c1f9c..eaed2626ffda 100644
--- a/arch/ia64/include/asm/dma.h
+++ b/arch/ia64/include/asm/dma.h
@@ -12,8 +12,6 @@
 
 extern unsigned long MAX_DMA_ADDRESS;
 
-extern int isa_dma_bridge_buggy;
-
 #define free_dma(x)
 
 #endif /* _ASM_IA64_DMA_H */
diff --git a/arch/m68k/include/asm/dma.h b/arch/m68k/include/asm/dma.h
index f6c5e0dfb4e5..1c8d9c5bc2fa 100644
--- a/arch/m68k/include/asm/dma.h
+++ b/arch/m68k/include/asm/dma.h
@@ -6,10 +6,4 @@
    bootmem allocator (but this should do it for this) */
 #define MAX_DMA_ADDRESS PAGE_OFFSET
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy    (0)
-#endif
-
 #endif /* _M68K_DMA_H */
diff --git a/arch/microblaze/include/asm/dma.h b/arch/microblaze/include/asm/dma.h
index f801582be912..7484c9eb66c4 100644
--- a/arch/microblaze/include/asm/dma.h
+++ b/arch/microblaze/include/asm/dma.h
@@ -9,10 +9,4 @@
 /* Virtual address corresponding to last available physical memory address.  */
 #define MAX_DMA_ADDRESS (CONFIG_KERNEL_START + memory_size - 1)
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy     (0)
-#endif
-
 #endif /* _ASM_MICROBLAZE_DMA_H */
diff --git a/arch/mips/include/asm/dma.h b/arch/mips/include/asm/dma.h
index be726b943530..d6186e6bea7e 100644
--- a/arch/mips/include/asm/dma.h
+++ b/arch/mips/include/asm/dma.h
@@ -307,12 +307,4 @@ static __inline__ int get_dma_residue(unsigned int dmanr)
 extern int request_dma(unsigned int dmanr, const char * device_id);	/* reserve a DMA channel */
 extern void free_dma(unsigned int dmanr);	/* release it again */
 
-/* From PCI */
-
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* _ASM_DMA_H */
diff --git a/arch/parisc/include/asm/dma.h b/arch/parisc/include/asm/dma.h
index eea80ed34e6d..9e8c101de902 100644
--- a/arch/parisc/include/asm/dma.h
+++ b/arch/parisc/include/asm/dma.h
@@ -176,10 +176,4 @@ static __inline__ void set_dma_count(unsigned int dmanr, unsigned int count)
 
 #define free_dma(dmanr)
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy 	(0)
-#endif
-
 #endif /* _ASM_DMA_H */
diff --git a/arch/powerpc/include/asm/dma.h b/arch/powerpc/include/asm/dma.h
index 6161a9596196..d97c66d9ae34 100644
--- a/arch/powerpc/include/asm/dma.h
+++ b/arch/powerpc/include/asm/dma.h
@@ -340,11 +340,5 @@ extern int request_dma(unsigned int dmanr, const char *device_id);
 /* release it again */
 extern void free_dma(unsigned int dmanr);
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* __KERNEL__ */
 #endif	/* _ASM_POWERPC_DMA_H */
diff --git a/arch/s390/include/asm/dma.h b/arch/s390/include/asm/dma.h
index 6f26f35d4a71..dec1c4ce628c 100644
--- a/arch/s390/include/asm/dma.h
+++ b/arch/s390/include/asm/dma.h
@@ -11,10 +11,4 @@
  */
 #define MAX_DMA_ADDRESS         0x80000000
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* _ASM_S390_DMA_H */
diff --git a/arch/sh/include/asm/dma.h b/arch/sh/include/asm/dma.h
index 17d23ae98c77..c8bee3f985a2 100644
--- a/arch/sh/include/asm/dma.h
+++ b/arch/sh/include/asm/dma.h
@@ -137,10 +137,4 @@ extern int register_chan_caps(const char *dmac, struct dma_chan_caps *capslist);
 extern int dma_create_sysfs_files(struct dma_channel *, struct dma_info *);
 extern void dma_remove_sysfs_files(struct dma_channel *, struct dma_info *);
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* __ASM_SH_DMA_H */
diff --git a/arch/sparc/include/asm/dma.h b/arch/sparc/include/asm/dma.h
index 462e7c794a09..08043f35b110 100644
--- a/arch/sparc/include/asm/dma.h
+++ b/arch/sparc/include/asm/dma.h
@@ -82,14 +82,6 @@
 #define DMA_BURST64      0x40
 #define DMA_BURSTBITS    0x7f
 
-/* From PCI */
-
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy 	(0)
-#endif
-
 #ifdef CONFIG_SPARC32
 struct device;
 
diff --git a/arch/x86/include/asm/dma.h b/arch/x86/include/asm/dma.h
index 8e95aa4b0d17..0c34c658f57d 100644
--- a/arch/x86/include/asm/dma.h
+++ b/arch/x86/include/asm/dma.h
@@ -309,10 +309,12 @@ extern void free_dma(unsigned int dmanr);
 
 /* From PCI */
 
+#ifdef CONFIG_X86_32
 #ifdef CONFIG_PCI
 extern int isa_dma_bridge_buggy;
 #else
 #define isa_dma_bridge_buggy	(0)
-#endif
+#endif /* CONFIG_PCI */
+#endif /* CONFIG_X86_32 */
 
 #endif /* _ASM_X86_DMA_H */
diff --git a/arch/xtensa/include/asm/dma.h b/arch/xtensa/include/asm/dma.h
index bb099a373b5a..172644539032 100644
--- a/arch/xtensa/include/asm/dma.h
+++ b/arch/xtensa/include/asm/dma.h
@@ -52,11 +52,4 @@
 extern int request_dma(unsigned int dmanr, const char * device_id);
 extern void free_dma(unsigned int dmanr);
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy 	(0)
-#endif
-
-
 #endif
diff --git a/drivers/comedi/drivers/comedi_isadma.c b/drivers/comedi/drivers/comedi_isadma.c
index 700982464c53..508421809128 100644
--- a/drivers/comedi/drivers/comedi_isadma.c
+++ b/drivers/comedi/drivers/comedi_isadma.c
@@ -104,8 +104,10 @@ unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
 
 	flags = claim_dma_lock();
 	clear_dma_ff(desc->chan);
+#ifdef CONFIG_X86_32
 	if (!isa_dma_bridge_buggy)
 		disable_dma(desc->chan);
+#endif
 	result = get_dma_residue(desc->chan);
 	/*
 	 * Read the counter again and choose higher value in order to
@@ -113,8 +115,10 @@ unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
 	 * isa_dma_bridge_buggy is set.
 	 */
 	result1 = get_dma_residue(desc->chan);
+#ifdef CONFIG_X86_32
 	if (!isa_dma_bridge_buggy)
 		enable_dma(desc->chan);
+#endif
 	release_dma_lock(flags);
 
 	if (result < result1)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index cfaf40a540a8..60c55d2cb2cc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -41,8 +41,10 @@ const char *pci_power_names[] = {
 };
 EXPORT_SYMBOL_GPL(pci_power_names);
 
+#ifdef CONFIG_X86_32
 int isa_dma_bridge_buggy;
 EXPORT_SYMBOL(isa_dma_bridge_buggy);
+#endif
 
 int pci_pci_problems;
 EXPORT_SYMBOL(pci_pci_problems);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 41aeaa235132..cb7715a0f339 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -239,6 +239,7 @@ static void quirk_passive_release(struct pci_dev *dev)
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	PCI_DEVICE_ID_INTEL_82441,	quirk_passive_release);
 DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_INTEL,	PCI_DEVICE_ID_INTEL_82441,	quirk_passive_release);
 
+#ifdef CONFIG_X86_32
 /*
  * The VIA VP2/VP3/MVP3 seem to have some 'features'. There may be a
  * workaround but VIA don't answer queries. If you happen to have good
@@ -265,6 +266,7 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AL,	PCI_DEVICE_ID_AL_M1533,		quirk_isa_dma
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NEC,	PCI_DEVICE_ID_NEC_CBUS_1,	quirk_isa_dma_hangs);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NEC,	PCI_DEVICE_ID_NEC_CBUS_2,	quirk_isa_dma_hangs);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NEC,	PCI_DEVICE_ID_NEC_CBUS_3,	quirk_isa_dma_hangs);
+#endif
 
 /*
  * Intel NM10 "TigerPoint" LPC PM1a_STS.BM_STS must be clear
diff --git a/include/asm-generic/pci.h b/include/asm-generic/pci.h
index 556147983911..3ceb0cb12321 100644
--- a/include/asm-generic/pci.h
+++ b/include/asm-generic/pci.h
@@ -18,8 +18,6 @@
 #define pcibios_assign_all_busses() 1
 #endif
 
-extern int isa_dma_bridge_buggy;
-
 /* Enable generic resource mapping code in drivers/pci/ */
 #define ARCH_GENERIC_PCI_MMAP_RESOURCE
 
diff --git a/sound/core/isadma.c b/sound/core/isadma.c
index 1f45ede023b4..8a6397109c56 100644
--- a/sound/core/isadma.c
+++ b/sound/core/isadma.c
@@ -73,8 +73,10 @@ unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
 
 	flags = claim_dma_lock();
 	clear_dma_ff(dma);
+#ifdef CONFIG_X86_32
 	if (!isa_dma_bridge_buggy)
 		disable_dma(dma);
+#endif
 	result = get_dma_residue(dma);
 	/*
 	 * HACK - read the counter again and choose higher value in order to
@@ -82,8 +84,10 @@ unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
 	 * isa_dma_bridge_buggy is set.
 	 */
 	result1 = get_dma_residue(dma);
+#ifdef CONFIG_X86_32
 	if (!isa_dma_bridge_buggy)
 		enable_dma(dma);
+#endif
 	release_dma_lock(flags);
 	if (unlikely(result < result1))
 		result = result1;

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Arnd Bergmann]

On Tue, Jul 19, 2022 at 12:55 PM Stafford Horne <shorne@gmail.com> wrote:

> diff --git a/drivers/comedi/drivers/comedi_isadma.c b/drivers/comedi/drivers/comedi_isadma.c
> index 700982464c53..508421809128 100644
> --- a/drivers/comedi/drivers/comedi_isadma.c
> +++ b/drivers/comedi/drivers/comedi_isadma.c
> @@ -104,8 +104,10 @@ unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
>
>         flags = claim_dma_lock();
>         clear_dma_ff(desc->chan);
> +#ifdef CONFIG_X86_32
>         if (!isa_dma_bridge_buggy)
>                 disable_dma(desc->chan);
> +#endif

There is a logic mistake here: if we are on something other than x86-32,
this always needs to call the disable_dma()/enable_dma().

Not sure how to best express this in a readable way, something like this
would work:

#ifdef CONFIG_X86_32
        if (!isa_dma_bridge_buggy)
#endif
               disable_dma(desc->chan);


or possibly at the start of this file, a

#ifndef CONFIG_X86_32
#define isa_dma_bridge_buggy 0
#endif

Or we could try to keep the generic definition in a global header
like linux/isa-dma.h.

> --- a/sound/core/isadma.c
> +++ b/sound/core/isadma.c
> @@ -73,8 +73,10 @@ unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
>
>         flags = claim_dma_lock();
>         clear_dma_ff(dma);
> +#ifdef CONFIG_X86_32
>         if (!isa_dma_bridge_buggy)
>                 disable_dma(dma);
> +#endif
>         result = get_dma_residue(dma);
>         /*

Same here.

         Arnd

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

On Tue, Jul 19, 2022 at 01:55:03PM +0200, Arnd Bergmann wrote:
> On Tue, Jul 19, 2022 at 12:55 PM Stafford Horne <shorne@gmail.com> wrote:
> 
> > diff --git a/drivers/comedi/drivers/comedi_isadma.c b/drivers/comedi/drivers/comedi_isadma.c
> > index 700982464c53..508421809128 100644
> > --- a/drivers/comedi/drivers/comedi_isadma.c
> > +++ b/drivers/comedi/drivers/comedi_isadma.c
> > @@ -104,8 +104,10 @@ unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
> >
> >         flags = claim_dma_lock();
> >         clear_dma_ff(desc->chan);
> > +#ifdef CONFIG_X86_32
> >         if (!isa_dma_bridge_buggy)
> >                 disable_dma(desc->chan);
> > +#endif
> 
> There is a logic mistake here: if we are on something other than x86-32,
> this always needs to call the disable_dma()/enable_dma().

Oops, thats right.  Sorry, I should have noticed that.

> Not sure how to best express this in a readable way, something like this
> would work:

Option 1:

> #ifdef CONFIG_X86_32
>         if (!isa_dma_bridge_buggy)
> #endif
>                disable_dma(desc->chan);
> 
> 
> or possibly at the start of this file, a

Option 2:

> #ifndef CONFIG_X86_32
> #define isa_dma_bridge_buggy 0
> #endif

Option 3:

> Or we could try to keep the generic definition in a global header
> like linux/isa-dma.h.

Perhaps option 3 makes the whole patch the most clean.

-Stafford

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

On Tue, Jul 19, 2022 at 09:23:36PM +0900, Stafford Horne wrote:
> On Tue, Jul 19, 2022 at 01:55:03PM +0200, Arnd Bergmann wrote:
> > On Tue, Jul 19, 2022 at 12:55 PM Stafford Horne <shorne@gmail.com> wrote:
> > 
> > > diff --git a/drivers/comedi/drivers/comedi_isadma.c b/drivers/comedi/drivers/comedi_isadma.c
> > > index 700982464c53..508421809128 100644
> > > --- a/drivers/comedi/drivers/comedi_isadma.c
> > > +++ b/drivers/comedi/drivers/comedi_isadma.c
> > > @@ -104,8 +104,10 @@ unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
> > >
> > >         flags = claim_dma_lock();
> > >         clear_dma_ff(desc->chan);
> > > +#ifdef CONFIG_X86_32
> > >         if (!isa_dma_bridge_buggy)
> > >                 disable_dma(desc->chan);
> > > +#endif
> > 
> > There is a logic mistake here: if we are on something other than x86-32,
> > this always needs to call the disable_dma()/enable_dma().
> 
> Oops, thats right.  Sorry, I should have noticed that.
> 
> > Not sure how to best express this in a readable way, something like this
> > would work:
> 
> Option 1:
> 
> > #ifdef CONFIG_X86_32
> >         if (!isa_dma_bridge_buggy)
> > #endif
> >                disable_dma(desc->chan);
> > 
> > 
> > or possibly at the start of this file, a
> 
> Option 2:
> 
> > #ifndef CONFIG_X86_32
> > #define isa_dma_bridge_buggy 0
> > #endif
> 
> Option 3:
> 
> > Or we could try to keep the generic definition in a global header
> > like linux/isa-dma.h.
> 
> Perhaps option 3 makes the whole patch the most clean.

And this is the result, I will get this into the series and create a v4 tomorrow
if no issues.

-Stafford

--

diff --git a/arch/alpha/include/asm/dma.h b/arch/alpha/include/asm/dma.h
index 28610ea7786d..a04d76b96089 100644
--- a/arch/alpha/include/asm/dma.h
+++ b/arch/alpha/include/asm/dma.h
@@ -365,13 +365,4 @@ extern void free_dma(unsigned int dmanr);	/* release it again */
 #define KERNEL_HAVE_CHECK_DMA
 extern int check_dma(unsigned int dmanr);
 
-/* From PCI */
-
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy 	(0)
-#endif
-
-
 #endif /* _ASM_DMA_H */
diff --git a/arch/arc/include/asm/dma.h b/arch/arc/include/asm/dma.h
index 5b744f4b10a7..02431027ed2f 100644
--- a/arch/arc/include/asm/dma.h
+++ b/arch/arc/include/asm/dma.h
@@ -7,10 +7,5 @@
 #define ASM_ARC_DMA_H
 
 #define MAX_DMA_ADDRESS 0xC0000000
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	0
-#endif
 
 #endif
diff --git a/arch/arm/include/asm/dma.h b/arch/arm/include/asm/dma.h
index a81dda65c576..907d139be431 100644
--- a/arch/arm/include/asm/dma.h
+++ b/arch/arm/include/asm/dma.h
@@ -143,10 +143,4 @@ extern int  get_dma_residue(unsigned int chan);
 
 #endif /* CONFIG_ISA_DMA_API */
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy    (0)
-#endif
-
 #endif /* __ASM_ARM_DMA_H */
diff --git a/arch/ia64/include/asm/dma.h b/arch/ia64/include/asm/dma.h
index 59625e9c1f9c..eaed2626ffda 100644
--- a/arch/ia64/include/asm/dma.h
+++ b/arch/ia64/include/asm/dma.h
@@ -12,8 +12,6 @@
 
 extern unsigned long MAX_DMA_ADDRESS;
 
-extern int isa_dma_bridge_buggy;
-
 #define free_dma(x)
 
 #endif /* _ASM_IA64_DMA_H */
diff --git a/arch/m68k/include/asm/dma.h b/arch/m68k/include/asm/dma.h
index f6c5e0dfb4e5..1c8d9c5bc2fa 100644
--- a/arch/m68k/include/asm/dma.h
+++ b/arch/m68k/include/asm/dma.h
@@ -6,10 +6,4 @@
    bootmem allocator (but this should do it for this) */
 #define MAX_DMA_ADDRESS PAGE_OFFSET
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy    (0)
-#endif
-
 #endif /* _M68K_DMA_H */
diff --git a/arch/microblaze/include/asm/dma.h b/arch/microblaze/include/asm/dma.h
index f801582be912..7484c9eb66c4 100644
--- a/arch/microblaze/include/asm/dma.h
+++ b/arch/microblaze/include/asm/dma.h
@@ -9,10 +9,4 @@
 /* Virtual address corresponding to last available physical memory address.  */
 #define MAX_DMA_ADDRESS (CONFIG_KERNEL_START + memory_size - 1)
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy     (0)
-#endif
-
 #endif /* _ASM_MICROBLAZE_DMA_H */
diff --git a/arch/mips/include/asm/dma.h b/arch/mips/include/asm/dma.h
index be726b943530..d6186e6bea7e 100644
--- a/arch/mips/include/asm/dma.h
+++ b/arch/mips/include/asm/dma.h
@@ -307,12 +307,4 @@ static __inline__ int get_dma_residue(unsigned int dmanr)
 extern int request_dma(unsigned int dmanr, const char * device_id);	/* reserve a DMA channel */
 extern void free_dma(unsigned int dmanr);	/* release it again */
 
-/* From PCI */
-
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* _ASM_DMA_H */
diff --git a/arch/parisc/include/asm/dma.h b/arch/parisc/include/asm/dma.h
index eea80ed34e6d..9e8c101de902 100644
--- a/arch/parisc/include/asm/dma.h
+++ b/arch/parisc/include/asm/dma.h
@@ -176,10 +176,4 @@ static __inline__ void set_dma_count(unsigned int dmanr, unsigned int count)
 
 #define free_dma(dmanr)
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy 	(0)
-#endif
-
 #endif /* _ASM_DMA_H */
diff --git a/arch/powerpc/include/asm/dma.h b/arch/powerpc/include/asm/dma.h
index 6161a9596196..d97c66d9ae34 100644
--- a/arch/powerpc/include/asm/dma.h
+++ b/arch/powerpc/include/asm/dma.h
@@ -340,11 +340,5 @@ extern int request_dma(unsigned int dmanr, const char *device_id);
 /* release it again */
 extern void free_dma(unsigned int dmanr);
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* __KERNEL__ */
 #endif	/* _ASM_POWERPC_DMA_H */
diff --git a/arch/s390/include/asm/dma.h b/arch/s390/include/asm/dma.h
index 6f26f35d4a71..dec1c4ce628c 100644
--- a/arch/s390/include/asm/dma.h
+++ b/arch/s390/include/asm/dma.h
@@ -11,10 +11,4 @@
  */
 #define MAX_DMA_ADDRESS         0x80000000
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* _ASM_S390_DMA_H */
diff --git a/arch/sh/include/asm/dma.h b/arch/sh/include/asm/dma.h
index 17d23ae98c77..c8bee3f985a2 100644
--- a/arch/sh/include/asm/dma.h
+++ b/arch/sh/include/asm/dma.h
@@ -137,10 +137,4 @@ extern int register_chan_caps(const char *dmac, struct dma_chan_caps *capslist);
 extern int dma_create_sysfs_files(struct dma_channel *, struct dma_info *);
 extern void dma_remove_sysfs_files(struct dma_channel *, struct dma_info *);
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* __ASM_SH_DMA_H */
diff --git a/arch/sparc/include/asm/dma.h b/arch/sparc/include/asm/dma.h
index 462e7c794a09..08043f35b110 100644
--- a/arch/sparc/include/asm/dma.h
+++ b/arch/sparc/include/asm/dma.h
@@ -82,14 +82,6 @@
 #define DMA_BURST64      0x40
 #define DMA_BURSTBITS    0x7f
 
-/* From PCI */
-
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy 	(0)
-#endif
-
 #ifdef CONFIG_SPARC32
 struct device;
 
diff --git a/arch/x86/include/asm/dma.h b/arch/x86/include/asm/dma.h
index 8e95aa4b0d17..8ae6e0e11b8b 100644
--- a/arch/x86/include/asm/dma.h
+++ b/arch/x86/include/asm/dma.h
@@ -307,12 +307,4 @@ extern int request_dma(unsigned int dmanr, const char *device_id);
 extern void free_dma(unsigned int dmanr);
 #endif
 
-/* From PCI */
-
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy	(0)
-#endif
-
 #endif /* _ASM_X86_DMA_H */
diff --git a/arch/xtensa/include/asm/dma.h b/arch/xtensa/include/asm/dma.h
index bb099a373b5a..172644539032 100644
--- a/arch/xtensa/include/asm/dma.h
+++ b/arch/xtensa/include/asm/dma.h
@@ -52,11 +52,4 @@
 extern int request_dma(unsigned int dmanr, const char * device_id);
 extern void free_dma(unsigned int dmanr);
 
-#ifdef CONFIG_PCI
-extern int isa_dma_bridge_buggy;
-#else
-#define isa_dma_bridge_buggy 	(0)
-#endif
-
-
 #endif
diff --git a/drivers/comedi/drivers/comedi_isadma.c b/drivers/comedi/drivers/comedi_isadma.c
index 700982464c53..1d470b0da34c 100644
--- a/drivers/comedi/drivers/comedi_isadma.c
+++ b/drivers/comedi/drivers/comedi_isadma.c
@@ -8,6 +8,7 @@
 #include <linux/slab.h>
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
+#include <linux/isa-dma.h>
 #include <asm/dma.h>
 #include <linux/comedi/comedidev.h>
 #include <linux/comedi/comedi_isadma.h>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index cfaf40a540a8..60c55d2cb2cc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -41,8 +41,10 @@ const char *pci_power_names[] = {
 };
 EXPORT_SYMBOL_GPL(pci_power_names);
 
+#ifdef CONFIG_X86_32
 int isa_dma_bridge_buggy;
 EXPORT_SYMBOL(isa_dma_bridge_buggy);
+#endif
 
 int pci_pci_problems;
 EXPORT_SYMBOL(pci_pci_problems);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 41aeaa235132..6fc64509eee7 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -17,6 +17,7 @@
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/pci.h>
+#include <linux/isa-dma.h> /* isa_dma_bridge_buggy */
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/acpi.h>
@@ -30,7 +31,6 @@
 #include <linux/pm_runtime.h>
 #include <linux/suspend.h>
 #include <linux/switchtec.h>
-#include <asm/dma.h>	/* isa_dma_bridge_buggy */
 #include "pci.h"
 
 static ktime_t fixup_debug_start(struct pci_dev *dev,
@@ -239,6 +239,7 @@ static void quirk_passive_release(struct pci_dev *dev)
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	PCI_DEVICE_ID_INTEL_82441,	quirk_passive_release);
 DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_INTEL,	PCI_DEVICE_ID_INTEL_82441,	quirk_passive_release);
 
+#ifdef CONFIG_X86_32
 /*
  * The VIA VP2/VP3/MVP3 seem to have some 'features'. There may be a
  * workaround but VIA don't answer queries. If you happen to have good
@@ -265,6 +266,7 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AL,	PCI_DEVICE_ID_AL_M1533,		quirk_isa_dma
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NEC,	PCI_DEVICE_ID_NEC_CBUS_1,	quirk_isa_dma_hangs);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NEC,	PCI_DEVICE_ID_NEC_CBUS_2,	quirk_isa_dma_hangs);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NEC,	PCI_DEVICE_ID_NEC_CBUS_3,	quirk_isa_dma_hangs);
+#endif
 
 /*
  * Intel NM10 "TigerPoint" LPC PM1a_STS.BM_STS must be clear
diff --git a/include/asm-generic/pci.h b/include/asm-generic/pci.h
index 556147983911..3ceb0cb12321 100644
--- a/include/asm-generic/pci.h
+++ b/include/asm-generic/pci.h
@@ -18,8 +18,6 @@
 #define pcibios_assign_all_busses() 1
 #endif
 
-extern int isa_dma_bridge_buggy;
-
 /* Enable generic resource mapping code in drivers/pci/ */
 #define ARCH_GENERIC_PCI_MMAP_RESOURCE
 
diff --git a/include/linux/isa-dma.h b/include/linux/isa-dma.h
new file mode 100644
index 000000000000..9514f0949fa1
--- /dev/null
+++ b/include/linux/isa-dma.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __LINUX_ISA_DMA_H
+#define __LINUX_ISA_DMA_H
+
+#if defined(CONFIG_PCI) && defined(CONFIG_X86_32)
+extern int isa_dma_bridge_buggy;
+#else
+#define isa_dma_bridge_buggy	(0)
+#endif
+
+#endif /* __LINUX_ISA_DMA_H */
diff --git a/sound/core/isadma.c b/sound/core/isadma.c
index 1f45ede023b4..9516cfb3d237 100644
--- a/sound/core/isadma.c
+++ b/sound/core/isadma.c
@@ -12,6 +12,7 @@
 #undef HAVE_REALLY_SLOW_DMA_CONTROLLER
 
 #include <linux/export.h>
+#include <linux/isa-dma.h>
 #include <sound/core.h>
 #include <asm/dma.h>
 

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Arnd Bergmann]

On Tue, Jul 19, 2022 at 3:05 PM Stafford Horne <shorne@gmail.com> wrote:
> On Tue, Jul 19, 2022 at 09:23:36PM +0900, Stafford Horne wrote:
> > On Tue, Jul 19, 2022 at 01:55:03PM +0200, Arnd Bergmann wrote:

>
> And this is the result, I will get this into the series and create a v4 tomorrow
> if no issues.

Looks good to me, just one detail:

> diff --git a/include/linux/isa-dma.h b/include/linux/isa-dma.h
> new file mode 100644
> index 000000000000..9514f0949fa1
> --- /dev/null
> +++ b/include/linux/isa-dma.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __LINUX_ISA_DMA_H
> +#define __LINUX_ISA_DMA_H
> +
> +#if defined(CONFIG_PCI) && defined(CONFIG_X86_32)
> +extern int isa_dma_bridge_buggy;
> +#else
> +#define isa_dma_bridge_buggy   (0)
> +#endif
> +
> +#endif /* __LINUX_ISA_DMA_H */

I would make this file #include <asm/dma.h> as a step towards making
linux/isa-dma.h the official replacement for it in the driver api.

Including asm/dma.h from a driver is already a bit awkward, since we
are generally moving towards including only linux/*.h type headers, and
the dma.h name is too generic for something that is completely obsolete.

        Arnd

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

On Tue, Jul 19, 2022 at 03:18:17PM +0200, Arnd Bergmann wrote:
> On Tue, Jul 19, 2022 at 3:05 PM Stafford Horne <shorne@gmail.com> wrote:
> > On Tue, Jul 19, 2022 at 09:23:36PM +0900, Stafford Horne wrote:
> > > On Tue, Jul 19, 2022 at 01:55:03PM +0200, Arnd Bergmann wrote:
> 
> >
> > And this is the result, I will get this into the series and create a v4 tomorrow
> > if no issues.
> 
> Looks good to me, just one detail:
> 
> > diff --git a/include/linux/isa-dma.h b/include/linux/isa-dma.h
> > new file mode 100644
> > index 000000000000..9514f0949fa1
> > --- /dev/null
> > +++ b/include/linux/isa-dma.h
> > @@ -0,0 +1,12 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +
> > +#ifndef __LINUX_ISA_DMA_H
> > +#define __LINUX_ISA_DMA_H
> > +
> > +#if defined(CONFIG_PCI) && defined(CONFIG_X86_32)
> > +extern int isa_dma_bridge_buggy;
> > +#else
> > +#define isa_dma_bridge_buggy   (0)
> > +#endif
> > +
> > +#endif /* __LINUX_ISA_DMA_H */
> 
> I would make this file #include <asm/dma.h> as a step towards making
> linux/isa-dma.h the official replacement for it in the driver api.
> 
> Including asm/dma.h from a driver is already a bit awkward, since we
> are generally moving towards including only linux/*.h type headers, and
> the dma.h name is too generic for something that is completely obsolete.

OK, that makes sense.  Then I can remove the asm/dma.h include from:
 - drivers/comedi/drivers/comedi_isadma.c
 - sound/core/isadma.c

-Stafford

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Christoph Hellwig]

On Tue, Jul 19, 2022 at 10:05:46PM +0900, Stafford Horne wrote:
> > > Or we could try to keep the generic definition in a global header
> > > like linux/isa-dma.h.
> > 
> > Perhaps option 3 makes the whole patch the most clean.
> 
> And this is the result, I will get this into the series and create a v4 tomorrow
> if no issues.

Yes, this is what I tried to suggest earlier and it looks fine to me.
If we want to overengineer it we could add a ISA_DMA_BRIDGE_BUGGY
Kconfig symbol and select it from x86.


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RE: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[David Laight]

From: Stafford Horne
> Sent: 19 July 2022 13:24
> 
> On Tue, Jul 19, 2022 at 01:55:03PM +0200, Arnd Bergmann wrote:
> > On Tue, Jul 19, 2022 at 12:55 PM Stafford Horne <shorne@gmail.com> wrote:
> >
> > > diff --git a/drivers/comedi/drivers/comedi_isadma.c b/drivers/comedi/drivers/comedi_isadma.c
> > > index 700982464c53..508421809128 100644
> > > --- a/drivers/comedi/drivers/comedi_isadma.c
> > > +++ b/drivers/comedi/drivers/comedi_isadma.c
> > > @@ -104,8 +104,10 @@ unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
> > >
> > >         flags = claim_dma_lock();
> > >         clear_dma_ff(desc->chan);
> > > +#ifdef CONFIG_X86_32
> > >         if (!isa_dma_bridge_buggy)
> > >                 disable_dma(desc->chan);
> > > +#endif
> >
> > There is a logic mistake here: if we are on something other than x86-32,
> > this always needs to call the disable_dma()/enable_dma().
> 
> Oops, thats right.  Sorry, I should have noticed that.
> 
> > Not sure how to best express this in a readable way, something like this
> > would work:
> 
> Option 1:
> 
> > #ifdef CONFIG_X86_32
> >         if (!isa_dma_bridge_buggy)
> > #endif
> >                disable_dma(desc->chan);
> >
> >
> > or possibly at the start of this file, a
> 
> Option 2:
> 
> > #ifndef CONFIG_X86_32
> > #define isa_dma_bridge_buggy 0
> > #endif
> 
> Option 3:
> 
> > Or we could try to keep the generic definition in a global header
> > like linux/isa-dma.h.
> 
> Perhaps option 3 makes the whole patch the most clean.

Isn't there a define that can be used inside an if?
So you could do:
		if (!IS_CONFIG_X86_32 || !isa_dma_bridge_buggy)
			disable_dma();
(but I can't remember the name!)

	David

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

On Tue, Jul 19, 2022 at 07:32:46AM -0700, Christoph Hellwig wrote:
> On Tue, Jul 19, 2022 at 10:05:46PM +0900, Stafford Horne wrote:
> > > > Or we could try to keep the generic definition in a global header
> > > > like linux/isa-dma.h.
> > > 
> > > Perhaps option 3 makes the whole patch the most clean.
> > 
> > And this is the result, I will get this into the series and create a v4 tomorrow
> > if no issues.
> 
> Yes, this is what I tried to suggest earlier and it looks fine to me.
> If we want to overengineer it we could add a ISA_DMA_BRIDGE_BUGGY
> Kconfig symbol and select it from x86.

I left it as X86_32, I feel it it would be more confusing/hard to maintain to
add the extra level of indirection.

-Stafford

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Re: [PATCH v2 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

On Tue, Jul 19, 2022 at 03:09:35PM +0000, David Laight wrote:
> From: Stafford Horne
> > Sent: 19 July 2022 13:24
> > 
> > On Tue, Jul 19, 2022 at 01:55:03PM +0200, Arnd Bergmann wrote:
> > > On Tue, Jul 19, 2022 at 12:55 PM Stafford Horne <shorne@gmail.com> wrote:

> > Option 3:
> > 
> > > Or we could try to keep the generic definition in a global header
> > > like linux/isa-dma.h.
> > 
> > Perhaps option 3 makes the whole patch the most clean.
> 
> Isn't there a define that can be used inside an if?
> So you could do:
> 		if (!IS_CONFIG_X86_32 || !isa_dma_bridge_buggy)
> 			disable_dma();
> (but I can't remember the name!)

I think you probably mean:

  if (IS_ENABLED(CONFIG_X86_32) ... )

That could work too, but we still want to move the definition of
isa_dma_bridge_buggy out of architectures and into the global header.  I have
gone with option 3 for now.

-Stafford

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