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Message-ID: <75ea07e52350df5d3581bd14939504f0896073aa.camel@physik.fu-berlin.de>
Subject: Re: [PATCH v5 3/4] arch/*/io.h: remove ioremap_uc in some
 architectures
From:   John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
To:     Baoquan He <bhe@redhat.com>, linux-kernel@vger.kernel.org
Cc:     linux-arch@vger.kernel.org, linux-mm@kvack.org,
        akpm@linux-foundation.org, arnd@arndb.de, jiaxun.yang@flygoat.com,
        mpe@ellerman.id.au, geert@linux-m68k.org, mcgrof@kernel.org,
        hch@infradead.org, tsbogend@alpha.franken.de, f.fainelli@gmail.com,
        deller@gmx.de, linux-alpha@vger.kernel.org,
        linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
        linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org,
        sparclinux@vger.kernel.org
Date:   Fri, 06 Oct 2023 10:31:59 +0200
In-Reply-To: <20230921110424.215592-4-bhe@redhat.com>
References: <20230921110424.215592-1-bhe@redhat.com>
         <20230921110424.215592-4-bhe@redhat.com>
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On Thu, 2023-09-21 at 19:04 +0800, Baoquan He wrote:
> ioremap_uc() is only meaningful on old x86-32 systems with the PAT
> extension, and on ia64 with its slightly unconventional ioremap()
> behavior. So remove the ioremap_uc() definition in architecutures
> other than x86 and ia64. These architectures all have asm-generic/io.h
> included and will have the default ioremap_uc() definition which
> returns NULL.
> 
> This changes the existing behaviour, while no need to worry about
> any breakage because in the only callsite of ioremap_uc(), code
> has been adjusted to eliminate the impact. Please see
> atyfb_setup_generic() of drivers/video/fbdev/aty/atyfb_base.c.
> 
> If any new invocation of ioremap_uc() need be added, please consider
> using ioremap() intead or adding a ARCH specific version if necessary.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
> Acked-by: Helge Deller <deller@gmx.de>  # parisc
> Cc: linux-alpha@vger.kernel.org
> Cc: linux-hexagon@vger.kernel.org
> Cc: linux-m68k@lists.linux-m68k.org
> Cc: linux-mips@vger.kernel.org
> Cc: linux-parisc@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-sh@vger.kernel.org
> Cc: sparclinux@vger.kernel.org
> ---
>  Documentation/driver-api/device-io.rst | 9 +++++----
>  arch/alpha/include/asm/io.h            | 1 -
>  arch/hexagon/include/asm/io.h          | 3 ---
>  arch/m68k/include/asm/kmap.h           | 1 -
>  arch/mips/include/asm/io.h             | 1 -
>  arch/parisc/include/asm/io.h           | 2 --
>  arch/powerpc/include/asm/io.h          | 1 -
>  arch/sh/include/asm/io.h               | 2 --
>  arch/sparc/include/asm/io_64.h         | 1 -
>  9 files changed, 5 insertions(+), 16 deletions(-)
> 
> diff --git a/Documentation/driver-api/device-io.rst b/Documentation/driver-api/device-io.rst
> index 2c7abd234f4e..d55384b106bd 100644
> --- a/Documentation/driver-api/device-io.rst
> +++ b/Documentation/driver-api/device-io.rst
> @@ -408,11 +408,12 @@ functions for details on the CPU side of things.
>  ioremap_uc()
>  ------------
>  
> -ioremap_uc() behaves like ioremap() except that on the x86 architecture without
> -'PAT' mode, it marks memory as uncached even when the MTRR has designated
> -it as cacheable, see Documentation/arch/x86/pat.rst.
> +ioremap_uc() is only meaningful on old x86-32 systems with the PAT extension,
> +and on ia64 with its slightly unconventional ioremap() behavior, everywhere
> +elss ioremap_uc() defaults to return NULL.
>  
> -Portable drivers should avoid the use of ioremap_uc().
> +
> +Portable drivers should avoid the use of ioremap_uc(), use ioremap() instead.
>  
>  ioremap_cache()
>  ---------------
> diff --git a/arch/alpha/include/asm/io.h b/arch/alpha/include/asm/io.h
> index 7aeaf7c30a6f..076f0e4e7f1e 100644
> --- a/arch/alpha/include/asm/io.h
> +++ b/arch/alpha/include/asm/io.h
> @@ -308,7 +308,6 @@ static inline void __iomem *ioremap(unsigned long port, unsigned long size)
>  }
>  
>  #define ioremap_wc ioremap
> -#define ioremap_uc ioremap
>  
>  static inline void iounmap(volatile void __iomem *addr)
>  {
> diff --git a/arch/hexagon/include/asm/io.h b/arch/hexagon/include/asm/io.h
> index e2b308e32a37..b7bc246dbcb1 100644
> --- a/arch/hexagon/include/asm/io.h
> +++ b/arch/hexagon/include/asm/io.h
> @@ -174,9 +174,6 @@ static inline void writel(u32 data, volatile void __iomem *addr)
>  #define _PAGE_IOREMAP (_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
>  		       (__HEXAGON_C_DEV << 6))
>  
> -#define ioremap_uc(addr, size) ioremap((addr), (size))
> -
> -
>  #define __raw_writel writel
>  
>  static inline void memcpy_fromio(void *dst, const volatile void __iomem *src,
> diff --git a/arch/m68k/include/asm/kmap.h b/arch/m68k/include/asm/kmap.h
> index 4efb3efa593a..b778f015c917 100644
> --- a/arch/m68k/include/asm/kmap.h
> +++ b/arch/m68k/include/asm/kmap.h
> @@ -25,7 +25,6 @@ static inline void __iomem *ioremap(unsigned long physaddr, unsigned long size)
>  	return __ioremap(physaddr, size, IOMAP_NOCACHE_SER);
>  }
>  
> -#define ioremap_uc ioremap
>  #define ioremap_wt ioremap_wt
>  static inline void __iomem *ioremap_wt(unsigned long physaddr,
>  				       unsigned long size)
> diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
> index 41d8bd5adef8..1ecf255efb40 100644
> --- a/arch/mips/include/asm/io.h
> +++ b/arch/mips/include/asm/io.h
> @@ -170,7 +170,6 @@ void iounmap(const volatile void __iomem *addr);
>   */
>  #define ioremap(offset, size)						\
>  	ioremap_prot((offset), (size), _CACHE_UNCACHED)
> -#define ioremap_uc		ioremap
>  
>  /*
>   * ioremap_cache -	map bus memory into CPU space
> diff --git a/arch/parisc/include/asm/io.h b/arch/parisc/include/asm/io.h
> index 366537042465..48630c78714a 100644
> --- a/arch/parisc/include/asm/io.h
> +++ b/arch/parisc/include/asm/io.h
> @@ -132,8 +132,6 @@ static inline void gsc_writeq(unsigned long long val, unsigned long addr)
>  
>  #define ioremap_wc(addr, size)  \
>  	ioremap_prot((addr), (size), _PAGE_IOREMAP)
> -#define ioremap_uc(addr, size)  \
> -	ioremap_prot((addr), (size), _PAGE_IOREMAP)
>  
>  #define pci_iounmap			pci_iounmap
>  
> diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
> index 0732b743e099..21bd3e8bffce 100644
> --- a/arch/powerpc/include/asm/io.h
> +++ b/arch/powerpc/include/asm/io.h
> @@ -900,7 +900,6 @@ void __iomem *ioremap_wt(phys_addr_t address, unsigned long size);
>  #endif
>  
>  void __iomem *ioremap_coherent(phys_addr_t address, unsigned long size);
> -#define ioremap_uc(addr, size)		ioremap((addr), (size))
>  #define ioremap_cache(addr, size) \
>  	ioremap_prot((addr), (size), pgprot_val(PAGE_KERNEL))
>  
> diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h
> index f2f38e9d489a..790bea22c9b5 100644
> --- a/arch/sh/include/asm/io.h
> +++ b/arch/sh/include/asm/io.h
> @@ -302,8 +302,6 @@ unsigned long long poke_real_address_q(unsigned long long addr,
>  	ioremap_prot((addr), (size), pgprot_val(PAGE_KERNEL))
>  #endif /* CONFIG_MMU */
>  
> -#define ioremap_uc	ioremap
> -
>  /*
>   * Convert a physical pointer to a virtual kernel pointer for /dev/mem
>   * access
> diff --git a/arch/sparc/include/asm/io_64.h b/arch/sparc/include/asm/io_64.h
> index 9303270b22f3..d8ee1442f303 100644
> --- a/arch/sparc/include/asm/io_64.h
> +++ b/arch/sparc/include/asm/io_64.h
> @@ -423,7 +423,6 @@ static inline void __iomem *ioremap(unsigned long offset, unsigned long size)
>  	return (void __iomem *)offset;
>  }
>  
> -#define ioremap_uc(X,Y)			ioremap((X),(Y))
>  #define ioremap_wc(X,Y)			ioremap((X),(Y))
>  #define ioremap_wt(X,Y)			ioremap((X),(Y))
>  static inline void __iomem *ioremap_np(unsigned long offset, unsigned long size)

Acked-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> (SuperH)

-- 
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: :' :  Debian Developer
`. `'   Physicist
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