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| author | Baoquan He <bhe@redhat.com> | 2023-09-21 19:04:23 +0800 |
|---|---|---|
| committer | Arnd Bergmann <arnd@arndb.de> | 2023-11-23 10:32:52 +0100 |
| commit | 026246f114d925b2ab97a60e8b4a5506bd035e9c (patch) | |
| tree | 82aa56239047ff7599e10032876ff6481fc45560 /Documentation/driver-api | |
| parent | 4bfb53e7d317c01f296b2feb2fae7c421c1d52dc (diff) | |
| download | linux-026246f114d925b2ab97a60e8b4a5506bd035e9c.tar.gz linux-026246f114d925b2ab97a60e8b4a5506bd035e9c.tar.bz2 linux-026246f114d925b2ab97a60e8b4a5506bd035e9c.zip | |
arch/*/io.h: remove ioremap_uc in some architectures
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
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> (SuperH)
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
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/device-io.rst | 9 |
1 files changed, 5 insertions, 4 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() --------------- |