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intel_idle: Introduce a helper for checking PC6

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Introduce the skx_is_pc6_disabled() for checking if PC6 is disabled and
switch the following functions to use it:

 - skx_idle_state_table_update()
 - spr_idle_state_table_update()

At the same time, clean them up improving the commentary and moving it to
the function kernel-doc.

Purely a clean up, no functional changes intended.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Link: https://patch.msgid.link/20260425072532.358365-4-dedekind1@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Artem Bityutskiy 2026-04-25 10:25:31 +03:00 committed by Rafael J. Wysocki
parent 06dbe26280
commit 27428514d2
1 changed files with 24 additions and 24 deletions
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48
drivers/idle/intel_idle.c
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@ -2079,12 +2079,13 @@ static void __init sklh_idle_state_table_update(void)
}
/**
* skx_idle_state_table_update - Adjust the Sky Lake/Cascade Lake
* idle states table.
* skx_is_pc6_disabled() - Check if PC6 is disabled in BIOS.
*
* Return: %true if PC6 is disabled, %false otherwise.
*/
static void __init skx_idle_state_table_update(void)
static bool __init skx_is_pc6_disabled(void)
{
unsigned long long msr;
u64 msr;
rdmsrq(MSR_PKG_CST_CONFIG_CONTROL, msr);
@ -2095,35 +2096,34 @@ static void __init skx_idle_state_table_update(void)
* 011b: C6 (retention)
* 111b: No Package C state limits.
*/
if ((msr & SKX_PKG_CST_LIMIT_MASK) < SKX_PKG_CST_LIMIT_PC6) {
/*
* Uses the CC6 + PC0 latency and 3 times of
* latency for target_residency if the PC6
* is disabled in BIOS. This is consistent
* with how intel_idle driver uses _CST
* to set the target_residency.
*/
return (msr & SKX_PKG_CST_LIMIT_MASK) < SKX_PKG_CST_LIMIT_PC6;
}
/**
* skx_idle_state_table_update - Adjust the SKX/CLX idle states table.
*
* Adjust Sky Lake or Cascade Lake Xeon idle states if PC6 is disabled in BIOS.
* Use the CC6 + PC0 latency and 3 times of that latency for target_residency.
* This is consistent with how the intel_idle driver uses _CST to set the
* target_residency.
*/
static void __init skx_idle_state_table_update(void)
{
if (skx_is_pc6_disabled()) {
skx_cstates[2].exit_latency = 92;
skx_cstates[2].target_residency = 276;
}
}
/**
* spr_idle_state_table_update - Adjust Sapphire Rapids idle states table.
* spr_idle_state_table_update - Adjust Sapphire Rapids Xeon idle states table.
*
* By default, the C6 state assumes the worst-case scenario of package C6.
* However, if PC6 is disabled in BIOS, update the numbers to match core C6.
*/
static void __init spr_idle_state_table_update(void)
{
unsigned long long msr;
/*
* By default, the C6 state assumes the worst-case scenario of package
* C6. However, if PC6 is disabled, we update the numbers to match
* core C6.
*/
rdmsrq(MSR_PKG_CST_CONFIG_CONTROL, msr);
/* Limit value 2 and above allow for PC6. */
if ((msr & SKX_PKG_CST_LIMIT_MASK) < SKX_PKG_CST_LIMIT_PC6) {
if (skx_is_pc6_disabled()) {
spr_cstates[2].exit_latency = 190;
spr_cstates[2].target_residency = 600;
}