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Commit 3be6a48f authored by Dave Jones's avatar Dave Jones
Browse files

[CPUFREQ] longhaul - disable PCI mastering around transition. 



The spec states that we have to do this, which is *horrid*.

Based on code from: Ken Staton <ken_staton@agilent.com>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
parent e131832c

arch/i386/kernel/cpu/cpufreq/longhaul.c

+45 −4
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/cpufreq.h>

#include <linux/slab.h>

#include <linux/string.h>

#include <linux/pci.h>



#include <asm/msr.h>

#include <asm/timex.h>
@@ -120,6 +121,11 @@ static void do_powersaver(union msr_longhaul *longhaul, 
			unsigned int clock_ratio_index)

{

	int version;

	unsigned long flags;

	struct pci_dev *dev;

	int i;

	u16 pci_cmd;

	u16 cmd_state[64];



	switch (cpu_model) {

	case CPU_EZRA_T:
@@ -137,17 +143,52 @@ static void do_powersaver(union msr_longhaul *longhaul, 
	longhaul->bits.SoftBusRatio4 = (clock_ratio_index & 0x10) >> 4;

	longhaul->bits.EnableSoftBusRatio = 1;

	longhaul->bits.RevisionKey = 0;

	local_irq_disable();

	wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);



	preempt_disable();

	local_irq_save(flags);



	/*

	 * get current pci bus master state for all devices

	 * and clear bus master bit

	 */

	dev = NULL;

	i = 0;

	do {

		dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);

		if (dev != NULL) {

			pci_read_config_word(dev, PCI_COMMAND, &pci_cmd);

			cmd_state[i++] = pci_cmd;

			pci_cmd &= ~PCI_COMMAND_MASTER;

			pci_write_config_word(dev, PCI_COMMAND, pci_cmd);

		}

	} while (dev != NULL);



	local_irq_enable();



	__hlt();

	wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);

	__hlt();



	local_irq_disable();



	/* restore pci bus master state for all devices */

	dev = NULL;

	i = 0;

	do {

		dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);

		if (dev != NULL) {

			pci_cmd = cmd_state[i++];

			pci_write_config_byte(dev, PCI_COMMAND, pci_cmd);

		}

	} while (dev != NULL);

	local_irq_restore(flags);

	preempt_enable();



	/* disable bus ratio bit */

	rdmsrl(MSR_VIA_LONGHAUL, longhaul->val);

	longhaul->bits.EnableSoftBusRatio = 0;

	longhaul->bits.RevisionKey = version;

	local_irq_disable();

	wrmsrl(MSR_VIA_LONGHAUL, longhaul->val);

	local_irq_enable();

}



/**