From: Rafał Bilski Date: Thu, 17 May 2007 20:39:02 +0000 (+0200) Subject: [CPUFREQ] Longhaul - Check ACPI "BM DMA in progress" bit X-Git-Tag: v2.6.23-rc1~1103^2~11 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=489dc5cb18932d3cedaef03e84890475db17a843;p=linux-2.6 [CPUFREQ] Longhaul - Check ACPI "BM DMA in progress" bit 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 Signed-off-by: Dave Jones --- diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c index 504c6c9107..ff48296664 100644 --- a/arch/i386/kernel/cpu/cpufreq/longhaul.c +++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c @@ -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"); } /*