[PATCH v2] intel_idle: Disable C1E on Jasper Lake and Elkhart Lake

[Kai-Heng Feng]

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 is enabled.

So adjust intel_idle to use _CST when state_table is absent, and disable
C1E on those two platforms.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219023
Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
---
v2:
 - Allow the driver to use _CST when state_table is absent.

 drivers/idle/intel_idle.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 9aab7abc2ae9..ac1c6f4f9c7f 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1475,6 +1475,10 @@ 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,
@@ -1538,6 +1542,8 @@ 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),
@@ -2075,7 +2081,7 @@ 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);
@@ -2209,7 +2215,11 @@ 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;
-- 
2.43.0