intel_idle: Disable promotion to C1E on Jasper Lake and Elkhart Lake

PCIe ethernet throughut is sub-optimal on Jasper Lake and Elkhart Lake.

The CPU can take long time to exit to C0 to handle IRQ and perform DMA
when C1E has been entered.

For this reason, adjust intel_idle to disable promotion to C1E and still
use C-states from ACPI _CST on those two platforms.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219023
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://patch.msgid.link/20240820041128.102452-1-kai.heng.feng@canonical.com
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index e20f57ac307ea6e567af2b1c1c56dd08c463a804..9457e34b9e3299514fd24660d196154f9a07d416 100644 (file)
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1520,6 +1520,10 @@ static const struct idle_cpu idle_cpu_dnv __initconst = {
        .use_acpi = true,
 };
 
+static const struct idle_cpu idle_cpu_tmt __initconst = {
+       .disable_promotion_to_c1e = true,
+};
+
 static const struct idle_cpu idle_cpu_snr __initconst = {
        .state_table = snr_cstates,
        .disable_promotion_to_c1e = true,
@@ -1584,6 +1588,8 @@ static const struct x86_cpu_id intel_idle_ids[] __initconst = {
        X86_MATCH_VFM(INTEL_ATOM_GOLDMONT,      &idle_cpu_bxt),
        X86_MATCH_VFM(INTEL_ATOM_GOLDMONT_PLUS, &idle_cpu_bxt),
        X86_MATCH_VFM(INTEL_ATOM_GOLDMONT_D,    &idle_cpu_dnv),
+       X86_MATCH_VFM(INTEL_ATOM_TREMONT,       &idle_cpu_tmt),
+       X86_MATCH_VFM(INTEL_ATOM_TREMONT_L,     &idle_cpu_tmt),
        X86_MATCH_VFM(INTEL_ATOM_TREMONT_D,     &idle_cpu_snr),
        X86_MATCH_VFM(INTEL_ATOM_CRESTMONT,     &idle_cpu_grr),
        X86_MATCH_VFM(INTEL_ATOM_CRESTMONT_X,   &idle_cpu_srf),
@@ -2121,7 +2127,7 @@ static void __init intel_idle_cpuidle_driver_init(struct cpuidle_driver *drv)
 
        drv->state_count = 1;
 
-       if (icpu)
+       if (icpu && icpu->state_table)
                intel_idle_init_cstates_icpu(drv);
        else
                intel_idle_init_cstates_acpi(drv);
@@ -2255,7 +2261,11 @@ static int __init intel_idle_init(void)
 
        icpu = (const struct idle_cpu *)id->driver_data;
        if (icpu) {
-               cpuidle_state_table = icpu->state_table;
+               if (icpu->state_table)
+                       cpuidle_state_table = icpu->state_table;
+               else if (!intel_idle_acpi_cst_extract())
+                       return -ENODEV;
+
                auto_demotion_disable_flags = icpu->auto_demotion_disable_flags;
                if (icpu->disable_promotion_to_c1e)
                        c1e_promotion = C1E_PROMOTION_DISABLE;