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From: Palmer Dabbelt <palmer@dabbelt.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Arnd Bergmann <arnd@arndb.de>,
	guoren@kernel.org, monstr@monstr.eu, green.hu@gmail.com,
	deanbo422@gmail.com, gxt@pku.edu.cn, x86@kernel.org,
	linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	nios2-dev@lists.rocketboards.org, openrisc@lists.librecores.org,
	linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
	sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org,
	linux-mtd@lists.infradead.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 10/21] asm-generic: ioremap_uc should behave the same with and without MMU
Date: Wed, 06 Nov 2019 09:56:34 -0800 (PST)
Message-ID: <mhng-3f709a8a-a8c3-4612-b4de-847d13b4af0a@palmer-si-x1c4> (raw)
In-Reply-To: <20191029064834.23438-11-hch@lst.de>

On Mon, 28 Oct 2019 23:48:23 PDT (-0700), Christoph Hellwig wrote:
> Whatever reason there is for the existence of ioremap_uc, and the fact
> that it returns NULL by default on architectures with an MMU applies
> equally to nommu architectures, so don't provide different defaults.
>
> In practice the difference is meaningless as the only portable driver
> that uses ioremap_uc is atyfb which probably doesn't show up on nommu
> devices.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  include/asm-generic/io.h | 36 ++++++++++++++++--------------------
>  1 file changed, 16 insertions(+), 20 deletions(-)
>
> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> index d02806513670..a98ed6325727 100644
> --- a/include/asm-generic/io.h
> +++ b/include/asm-generic/io.h
> @@ -935,18 +935,7 @@ static inline void *phys_to_virt(unsigned long address)
>   * defined your own ioremap_*() variant you must then declare your own
>   * ioremap_*() variant as defined to itself to avoid the default NULL return.
>   */
> -
> -#ifdef CONFIG_MMU
> -
> -#ifndef ioremap_uc
> -#define ioremap_uc ioremap_uc
> -static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size)
> -{
> -	return NULL;
> -}
> -#endif
> -
> -#else /* !CONFIG_MMU */
> +#ifndef CONFIG_MMU
>
>  /*
>   * Change "struct page" to physical address.
> @@ -980,14 +969,6 @@ static inline void __iomem *ioremap_nocache(phys_addr_t offset, size_t size)
>  }
>  #endif
>
> -#ifndef ioremap_uc
> -#define ioremap_uc ioremap_uc
> -static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size)
> -{
> -	return ioremap_nocache(offset, size);
> -}
> -#endif
> -
>  #ifndef ioremap_wc
>  #define ioremap_wc ioremap_wc
>  static inline void __iomem *ioremap_wc(phys_addr_t offset, size_t size)
> @@ -1004,6 +985,21 @@ static inline void __iomem *ioremap_wt(phys_addr_t offset, size_t size)
>  }
>  #endif
>
> +/*
> + * ioremap_uc is special in that we do require an explicit architecture
> + * implementation.  In general you do now want to use this function in a

Presumably that's supposed to be "do not want to use"?

> + * driver and use plain ioremap, which is uncached by default.  Similarly
> + * architectures should not implement it unless they have a very good
> + * reason.
> + */
> +#ifndef ioremap_uc
> +#define ioremap_uc ioremap_uc
> +static inline void __iomem *ioremap_uc(phys_addr_t offset, size_t size)
> +{
> +	return NULL;
> +}
> +#endif
> +
>  #ifdef CONFIG_HAS_IOPORT_MAP
>  #ifndef CONFIG_GENERIC_IOMAP
>  #ifndef ioport_map

With the fix:

Reviewed-by: Palmer Dabbelt <palmer@dabbelt.com>

  reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-29  6:48 generic ioremap (and lots of cleanups) v3 Christoph Hellwig
2019-10-29  6:48 ` [PATCH 01/21] arm: remove ioremap_cached Christoph Hellwig
2019-11-11 10:33   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 02/21] unicore32: " Christoph Hellwig
2019-10-29  6:48 ` [PATCH 03/21] ia64: rename ioremap_nocache to ioremap_uc Christoph Hellwig
2019-11-11 10:36   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 04/21] hexagon: clean up ioremap Christoph Hellwig
2019-10-29  6:48 ` [PATCH 05/21] alpha: remove the unused __ioremap wrapper Christoph Hellwig
2019-10-29  6:48 ` [PATCH 06/21] nios2: remove __ioremap Christoph Hellwig
2019-10-29  6:48 ` [PATCH 07/21] parisc: " Christoph Hellwig
2019-11-05 14:29   ` Helge Deller
2019-10-29  6:48 ` [PATCH 08/21] x86: Clean up ioremap() Christoph Hellwig
2019-10-30 10:39   ` Thomas Gleixner
2019-10-29  6:48 ` [PATCH 09/21] xtensa: clean up ioremap Christoph Hellwig
2019-10-29  6:48 ` [PATCH 10/21] asm-generic: ioremap_uc should behave the same with and without MMU Christoph Hellwig
2019-11-06 17:56   ` Palmer Dabbelt [this message]
2019-11-11 10:09   ` Arnd Bergmann
2019-11-11 10:15     ` Christoph Hellwig
2019-11-11 10:27       ` Arnd Bergmann
2019-11-11 10:29         ` Christoph Hellwig
2019-11-11 19:33           ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 11/21] asm-generic: don't provide ioremap for CONFIG_MMU Christoph Hellwig
2019-11-06 18:11   ` Palmer Dabbelt
2019-11-06 18:16     ` Geert Uytterhoeven
2019-11-06 18:28       ` Christoph Hellwig
2019-11-11 10:31       ` Arnd Bergmann
2019-11-11 10:29   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 12/21] arch: rely on asm-generic/io.h for default ioremap_* definitions Christoph Hellwig
2019-11-07 15:29   ` Palmer Dabbelt
2019-11-11 10:10   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 13/21] m68k: rename __iounmap and mark it static Christoph Hellwig
2019-10-30  8:51   ` Geert Uytterhoeven
2019-10-29  6:48 ` [PATCH 14/21] hexagon: remove __iounmap Christoph Hellwig
2019-10-29  6:48 ` [PATCH 15/21] nios2: " Christoph Hellwig
2019-10-29  6:48 ` [PATCH 16/21] sh: " Christoph Hellwig
2019-10-29  6:48 ` [PATCH 17/21] lib: provide a simple generic ioremap implementation Christoph Hellwig
2019-11-07 15:29   ` Palmer Dabbelt
2019-11-11 10:10   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 18/21] riscv: use the generic ioremap code Christoph Hellwig
2019-10-29  6:48 ` [PATCH 19/21] nds32: use generic ioremap Christoph Hellwig
2019-11-12  8:51   ` Greentime Hu
2019-10-29  6:48 ` [PATCH 20/21] csky: remove ioremap_cache Christoph Hellwig
2019-10-29  6:48 ` [PATCH 21/21] csky: use generic ioremap Christoph Hellwig
2019-11-05  1:31 ` generic ioremap (and lots of cleanups) v3 Christoph Hellwig
2019-11-07 20:47 ` generic-iomap tree for linux-next Christoph Hellwig
2019-11-08  2:20   ` Stephen Rothwell
2019-11-08  4:52     ` Stephen Rothwell
2019-11-08  5:14       ` Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2019-10-17 17:45 generic ioremap (and lots of cleanups) v2 Christoph Hellwig
2019-10-17 17:45 ` [PATCH 10/21] asm-generic: ioremap_uc should behave the same with and without MMU Christoph Hellwig

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