[XS] Change in coreboot[main]: mb/google/{rex,ovis}: Disable package C-state auto demotion for rex &...

[Sukumar Ghorai (Code Review)]

Sukumar Ghorai has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/78250?usp=email )

Change subject: mb/google/{rex,ovis}: Disable package C-state auto demotion for rex & ovis
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mb/google/{rex,ovis}: Disable package C-state auto demotion for rex & ovis

Package C-state auto demotion feature allows hardware to determine lower
C-state as per platform policy. Since platform sets performance policy to
balanced from hardware, auto demotion can be disabled without performance
impact.

Also, disabling this feature results soc to enter below PC8 state and
additional power savings ~30mW in Local-Video-Playback scenario.

Change-Id: Ia4cf4a7cb6bd5eaae26197b55f9385c078960d7b
Signed-off-by: Sukumar Ghorai 
---
M src/mainboard/google/rex/variants/baseboard/ovis/devicetree.cb
M src/mainboard/google/rex/variants/baseboard/rex/devicetree.cb
M src/soc/intel/meteorlake/chip.h
M src/soc/intel/meteorlake/fsp_params.c
4 files changed, 9 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/50/78250/1

diff --git a/src/mainboard/google/rex/variants/baseboard/ovis/devicetree.cb b/src/mainboard/google/rex/variants/baseboard/ovis/devicetree.cb
index 6fc0dc0..7d39ece 100644
--- a/src/mainboard/google/rex/variants/baseboard/ovis/devicetree.cb
+++ b/src/mainboard/google/rex/variants/baseboard/ovis/devicetree.cb
@@ -36,6 +36,9 @@
    # Disable C1 C-state auto-demotion
    register "disable_c1_state_auto_demotion" = "1"

+	# Disable PKGC-state demotion
+	register "disable_package_c_state_demotion" = "1"
+
    # Enable Energy Reporting
    register "pch_pm_energy_report_enable" = "1"

diff --git a/src/mainboard/google/rex/variants/baseboard/rex/devicetree.cb b/src/mainboard/google/rex/variants/baseboard/rex/devicetree.cb
index ec57ee7..5894fe6 100644
--- a/src/mainboard/google/rex/variants/baseboard/rex/devicetree.cb
+++ b/src/mainboard/google/rex/variants/baseboard/rex/devicetree.cb
@@ -36,6 +36,9 @@
    # Disable C1 C-state auto-demotion
    register "disable_c1_state_auto_demotion" = "1"

+	# Disable PKGC-state demotion
+	register "disable_package_c_state_demotion" = "1"
+
    # Enable Energy Reporting
    register "pch_pm_energy_report_enable" = "1"

diff --git a/src/soc/intel/meteorlake/chip.h b/src/soc/intel/meteorlake/chip.h
index ec38e80..6210406 100644
--- a/src/soc/intel/meteorlake/chip.h
+++ b/src/soc/intel/meteorlake/chip.h
@@ -419,6 +419,8 @@
     * Enable or Disable Package C-state Demotion.
     * Default is set to 0.
     * Set this to 1 in order to disable Package C-state demotion.
+	 * NOTE: Un-Demotion from demoted Package C-state needs to be disabled
+	 *       when auto demotion is disabled.
     */
    bool disable_package_c_state_demotion;

diff --git a/src/soc/intel/meteorlake/fsp_params.c b/src/soc/intel/meteorlake/fsp_params.c
index 5350783..5ec9cf4 100644
--- a/src/soc/intel/meteorlake/fsp_params.c
+++ b/src/soc/intel/meteorlake/fsp_params.c
@@ -666,6 +666,7 @@
    s_cfg->C1StateUnDemotion = !config->disable_c1_state_auto_demotion;
    s_cfg->C1StateAutoDemotion = !config->disable_c1_state_auto_demotion;
    s_cfg->PkgCStateDemotion = !config->disable_package_c_state_demotion;
+	s_cfg->PkgCStateUnDemotion = !config->disable_package_c_state_demotion;
    s_cfg->PmcV1p05PhyExtFetControlEn = 1;

/* Enable PCH to CPU energy report feature. */