Skip to content
Commit 04aaa7ba authored by David P. Reed's avatar David P. Reed Committed by Ingo Molnar
Browse files

x86: fix cmos read and write to not use inb_p and outb_p



fix code to access CMOS rtc registers so that it does not use inb_p and
outb_p routines, which are deprecated.  Extensive research on all known
CMOS RTC chipset timing shows that there is no need for a delay in
accessing the registers of these chips even on old machines. These chipa
are never on an expansion bus, but have always been "motherboard"
resources, either in the processor chipset or explicitly on the
motherboard, and they are not part of the ISA/LPC or PCI buses, so
delays should not be based on bus timing. The reason to fix it:

 1) port 80 writes often hang some laptops that use ENE EC chipsets,
    esp. those designed and manufactured by Quanta for HP;

 2) RTC accesses are timing sensitive, and extra microseconds may matter;

 3) the new "io_delay" function is calibrated by expansion bus timing needs,
    thus is not appropriate for access to CMOS rtc registers.

Signed-off-by: default avatarDavid P. Reed <dpreed@reed.com>
Acked-by: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 03ae5768
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment