linux-kernel - [PATCH AUTOSEL 6.11 005/244] intel_idle: Disable promotion to C1E on Jasper Lake and Elkhart Lake

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Message-ID: <20240925113641.1297102-5-sashal@kernel.org>
Date: Wed, 25 Sep 2024 07:23:46 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Kai-Heng Feng <kai.heng.feng@...onical.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	Sasha Levin <sashal@...nel.org>,
	jacob.jun.pan@...ux.intel.com,
	lenb@...nel.org,
	linux-pm@...r.kernel.org
Subject: [PATCH AUTOSEL 6.11 005/244] intel_idle: Disable promotion to C1E on Jasper Lake and Elkhart Lake

From: Kai-Heng Feng <kai.heng.feng@...onical.com>

[ Upstream commit 5bb33212b5c664396e5de4cd5a2999abb84a3978 ]

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@...onical.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@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 9aab7abc2ae90..ac1c6f4f9c7f2 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