[PATCH] Longhaul - Disable arbiter

["Rafał Bilski" <rafalbilski@interia.pl>]

ACPI C3 works for "Powersaver" processors, so use it 
only for them.

Older CPU will change frequency on "halt" only. But we 
can protect transition in two ways:
- by ACPI PM2 register, there is "bus master arbiter 
  disable" bit. This isn't tested because VIA mainboards 
  don't have PM2 register,
- by PLE133 PCI/AGP arbiter disable register. There 
  are two bits in this register. First is "PCI arbiter 
  disable", second "AGP arbiter disable". This is 
  working on VIA Epia 800 mainboards.

Test on bm_control is more proper because this is true 
when PM2 register exist.

Signed-off-by: Rafa³ Bilski <rafalbilski@interia.pl>

---

diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c
--- a/arch/i386/kernel/cpu/cpufreq/longhaul.c
+++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c
@@ -27,6 +27,7 @@ #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/init.h>
 #include <linux/cpufreq.h>
+#include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 
@@ -60,6 +61,7 @@ static int can_scale_voltage;
 static int vrmrev;
 static struct acpi_processor *pr = NULL;
 static struct acpi_processor_cx *cx = NULL;
+static int port22_en = 0;
 
 /* Module parameters */
 static int dont_scale_voltage;
@@ -124,10 +126,9 @@ static int longhaul_get_cpu_mult(void)
 
 /* For processor with BCR2 MSR */
 
-static void do_longhaul1(int cx_address, unsigned int clock_ratio_index)
+static void do_longhaul1(unsigned int clock_ratio_index)
 {
 	union msr_bcr2 bcr2;
-	u32 t;
 
 	rdmsrl(MSR_VIA_BCR2, bcr2.val);
 	/* Enable software clock multiplier */
@@ -136,13 +137,11 @@ static void do_longhaul1(int cx_address,
 
 	/* Sync to timer tick */
 	safe_halt();
-	ACPI_FLUSH_CPU_CACHE();
 	/* Change frequency on next halt or sleep */
 	wrmsrl(MSR_VIA_BCR2, bcr2.val);
-	/* Invoke C3 */
-	inb(cx_address);
-	/* Dummy op - must do something useless after P_LVL3 read */
-	t = inl(acpi_fadt.xpm_tmr_blk.address);
+	/* Invoke transition */
+	ACPI_FLUSH_CPU_CACHE();
+	halt();
 
 	/* Disable software clock multiplier */
 	local_irq_disable();
@@ -166,9 +165,9 @@ static void do_powersaver(int cx_address
 
 	/* Sync to timer tick */
 	safe_halt();
-	ACPI_FLUSH_CPU_CACHE();
 	/* Change frequency on next halt or sleep */
 	wrmsrl(MSR_VIA_LONGHAUL, longhaul.val);
+	ACPI_FLUSH_CPU_CACHE();
 	/* Invoke C3 */
 	inb(cx_address);
 	/* Dummy op - must do something useless after P_LVL3 read */
@@ -227,10 +226,13 @@ static void longhaul_setstate(unsigned i
 	outb(0xFF,0xA1);	/* Overkill */
 	outb(0xFE,0x21);	/* TMR0 only */
 
-	/* Disable bus master arbitration */
-	if (pr->flags.bm_check) {
+	if (pr->flags.bm_control) {
+ 		/* Disable bus master arbitration */
 		acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1,
 				  ACPI_MTX_DO_NOT_LOCK);
+	} else if (port22_en) {
+		/* Disable AGP and PCI arbiters */
+		outb(3, 0x22);
 	}
 
 	switch (longhaul_version) {
@@ -244,7 +246,7 @@ static void longhaul_setstate(unsigned i
 	 */
 	case TYPE_LONGHAUL_V1:
 	case TYPE_LONGHAUL_V2:
-		do_longhaul1(cx->address, clock_ratio_index);
+		do_longhaul1(clock_ratio_index);
 		break;
 
 	/*
@@ -259,14 +261,20 @@ static void longhaul_setstate(unsigned i
 	 * to work in practice.
 	 */
 	case TYPE_POWERSAVER:
+		/* Don't allow wakeup */
+		acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0,
+				  ACPI_MTX_DO_NOT_LOCK);
 		do_powersaver(cx->address, clock_ratio_index);
 		break;
 	}
 
-	/* Enable bus master arbitration */
-	if (pr->flags.bm_check) {
+	if (pr->flags.bm_control) {
+		/* Enable bus master arbitration */
 		acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0,
 				  ACPI_MTX_DO_NOT_LOCK);
+	} else if (port22_en) {
+		/* Enable arbiters */
+		outb(0, 0x22);
 	}
 
 	outb(pic2_mask,0xA1);	/* restore mask */
@@ -540,21 +548,33 @@ static acpi_status longhaul_walk_callbac
 	return 1;
 }
 
+/* VIA don't support PM2 reg, but have something similar */
+static int enable_arbiter_disable(void)
+{
+	struct pci_dev *dev;
+	u8 pci_cmd;
+
+	/* Find PLE133 host bridge */
+	dev = pci_find_device(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8601_0, NULL);
+	if (dev != NULL) {
+		/* Enable access to port 0x22 */
+		pci_read_config_byte(dev, 0x78, &pci_cmd);
+		if ( !(pci_cmd & 1<<7) ) {
+			pci_cmd |= 1<<7;
+			pci_write_config_byte(dev, 0x78, pci_cmd);
+		}
+		return 1;
+	}
+	return 0;
+}
+
 static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
 {
 	struct cpuinfo_x86 *c = cpu_data;
 	char *cpuname=NULL;
 	int ret;
 
-	/* Check ACPI support for C3 state */
-	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
-			 &longhaul_walk_callback, NULL, (void *)&pr);
-	if (pr == NULL) goto err_acpi;
-
-	cx = &pr->power.states[ACPI_STATE_C3];
-	if (cx->address == 0 || cx->latency > 1000) goto err_acpi;
-
-	/* Now check what we have on this motherboard */
+	/* Check what we have on this motherboard */
 	switch (c->x86_model) {
 	case 6:
 		cpu_model = CPU_SAMUEL;
@@ -636,6 +656,26 @@ static int __init longhaul_cpu_init(stru
 		break;
 	};
 
+	/* Find ACPI data for processor */
+	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
+			    &longhaul_walk_callback, NULL, (void *)&pr);
+	if (pr == NULL) goto err_acpi;
+
+	if (longhaul_version == TYPE_POWERSAVER) {
+		/* Check ACPI support for C3 state */
+		cx = &pr->power.states[ACPI_STATE_C3];
+		if (cx->address == 0 || cx->latency > 1000) goto err_acpi;
+	} else {
+		/* Check ACPI support for bus master arbiter disable */
+		if (!pr->flags.bm_control) {
+			if ( !enable_arbiter_disable() ) {
+				printk(KERN_ERR PFX "No ACPI support. No VT8601 host bridge. Aborting.\n");
+		    		return -ENODEV;
+			} else
+				port22_en = 1;
+		}
+	}
+
 	ret = longhaul_get_ranges();
 	if (ret != 0)
 		return ret;




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