[2.6.20.17 review 36/58] acpi-cpufreq: Proper ReadModifyWrite of PERF_CTL MSR

Willy Tarreau
2007-08-22T09:01:30Z

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[CPUFREQ] acpi-cpufreq: Proper ReadModifyWrite of PERF_CTL MSR

During recent acpi-cpufreq changes, writing to PERF_CTL msr
changed from RMW of entire 64 bit to RMW of low 32 bit and clearing of
upper 32 bit. Fix it back to do a proper RMW of the MSR.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c | 13 +++++--------
1 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
index 10baa35..18c8b67 100644
--- a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
+++ b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -167,11 +167,13 @@ static void do_drv_read(struct drv_cmd *cmd)

static void do_drv_write(struct drv_cmd *cmd)
{
- u32 h = 0;
+ u32 lo, hi;

switch (cmd->type) {
case SYSTEM_INTEL_MSR_CAPABLE:
- wrmsr(cmd->addr.msr.reg, cmd->val, h);
+ rdmsr(cmd->addr.msr.reg, lo, hi);
+ lo = (lo & ~INTEL_MSR_RANGE) | (cmd->val & INTEL_MSR_RANGE);
+ wrmsr(cmd->addr.msr.reg, lo, hi);
break;
case SYSTEM_IO_CAPABLE:
acpi_os_write_port((acpi_io_address)cmd->addr.io.port,
@@ -372,7 +374,6 @@ static int acpi_cpufreq_target(struct cpufreq_policy *policy,
struct cpufreq_freqs freqs;
cpumask_t online_policy_cpus;
struct drv_cmd cmd;
- unsigned int msr;
unsigned int next_state = 0; /* Index into freq_table */
unsigned int next_perf_state = 0; /* Index into perf table */
unsigned int i;
@@ -417,11 +418,7 @@ static int acpi_cpufreq_target(struct cpufreq_policy *policy,
case SYSTEM_INTEL_MSR_CAPABLE:
cmd.type = SYSTEM_INTEL_MSR_CAPABLE;
cmd.addr.msr.reg = MSR_IA32_PERF_CTL;
- msr =
- (u32) perf->states[next_perf_state].
- control & INTEL_MSR_RANGE;
- cmd.val = get_cur_val(online_policy_cpus);
- cmd.val = (cmd.val & ~INTEL_MSR_RANGE) | msr;
+ cmd.val = (u32) perf->states[next_perf_state].control;
break;
case SYSTEM_IO_CAPABLE:
cmd.type = SYSTEM_IO_CAPABLE;
--
1.5.2.5

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