linux-stable.git/include/linux/acpi_io.h, branch linux-2.6.38.y Linux kernel stable tree ACPI: Introduce acpi_os_ioremap() 2011-01-21T02:30:17+00:00 Rafael J. Wysocki rjw@sisk.pl 2011-01-19T21:27:14+00:00 2d6d9fd3a54a28c6f67f26eb6c74803307a1b11e Commit ca9b600be38c ("ACPI / PM: Make suspend_nvs_save() use acpi_os_map_memory()") attempted to prevent the code in osl.c and nvs.c from using different ioremap() variants by making the latter use acpi_os_map_memory() for mapping the NVS pages. However, that also requires acpi_os_unmap_memory() to be used for unmapping them, which causes synchronize_rcu() to be executed many times in a row unnecessarily and introduces substantial delays during resume on some systems. Instead of using acpi_os_map_memory() for mapping the NVS pages in nvs.c introduce acpi_os_ioremap() calling ioremap_cache() and make the code in both osl.c and nvs.c use it. Reported-by: Jeff Chua <jeff.chua.linux@gmail.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Commit ca9b600be38c ("ACPI / PM: Make suspend_nvs_save() use
acpi_os_map_memory()") attempted to prevent the code in osl.c and nvs.c
from using different ioremap() variants by making the latter use
acpi_os_map_memory() for mapping the NVS pages.  However, that also
requires acpi_os_unmap_memory() to be used for unmapping them, which
causes synchronize_rcu() to be executed many times in a row
unnecessarily and introduces substantial delays during resume on some
systems.

Instead of using acpi_os_map_memory() for mapping the NVS pages in nvs.c
introduce acpi_os_ioremap() calling ioremap_cache() and make the code in
both osl.c and nvs.c use it.

Reported-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>