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[CPUFREQ] Longhaul - Check ACPI "BM DMA in progress" bit

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It is good idea to wait for PCI bus to become idle before
frequency change. Thanks to ACPI it is possible. It makes
sense only when northbridge support is in use because it is
only case in which we can disable arbiter after check if PCI
bus is busy.

Signed-off-by: Rafal Bilski <rafalbilski@interia.pl>
Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
Rafał Bilski 2007-05-17 22:39:02 +02:00 committed by Dave Jones
parent 1b11d4ca6d
commit 489dc5cb18
1 changed files with 18 additions and 0 deletions
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18
arch/i386/kernel/cpu/cpufreq/longhaul.c
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@ -254,6 +254,8 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
struct cpufreq_freqs freqs;
unsigned long flags;
unsigned int pic1_mask, pic2_mask;
u32 bm_status = 0;
u32 bm_timeout = 100000;
if (old_ratio == clock_ratio_index)
return;
@ -284,6 +286,18 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
outb(0xFF,0xA1); /* Overkill */
outb(0xFE,0x21); /* TMR0 only */
/* Wait while PCI bus is busy. */
if (longhaul_flags & USE_NORTHBRIDGE
|| ((pr != NULL) && pr->flags.bm_control)) {
acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
while (bm_status && bm_timeout) {
acpi_set_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
bm_timeout--;
acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS,
&bm_status);
}
}
if (longhaul_flags & USE_NORTHBRIDGE) {
/* Disable AGP and PCI arbiters */
outb(3, 0x22);
@ -335,6 +349,10 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
freqs.new = calc_speed(longhaul_get_cpu_mult());
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
if (!bm_timeout)
printk(KERN_INFO PFX "Warning: Timeout while waiting for "
"idle PCI bus.\n");
}
/*