[coreboot-gerrit] [XS] Change in coreboot[master]: soc/intel/meteorlake: Fix black screen after booting to OS

[Subrata Banik (Code Review)]

Subrata Banik has submitted this change. ( https://review.coreboot.org/c/coreboot/+/77611?usp=email )

Change subject: soc/intel/meteorlake: Fix black screen after booting to OS
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soc/intel/meteorlake: Fix black screen after booting to OS

This patch ensures that the VR configuration for IA, SA, and GFX is
properly initialized, assigning zero values to VR causes a black screen
(no display) issue.

Problem Statement:
Override CEP (Current Excursion Protection) value with zero aka set to
disable results into black screen issue (no display).

Solution:
Keep CEP default enabled and don't override w/ zero value.

w/o this patch:
[SPEW ]   CPU_POWER_MGMT_VR_CONFIG : CepEnable[0] : 0x0
[SPEW ]   CPU_POWER_MGMT_VR_CONFIG : CepEnable[1] : 0x0
[SPEW ]   CPU_POWER_MGMT_VR_CONFIG : CepEnable[2] : 0x0

w/ this patch:
[SPEW ]   CPU_POWER_MGMT_VR_CONFIG : CepEnable[0] : 0x1
[SPEW ]   CPU_POWER_MGMT_VR_CONFIG : CepEnable[1] : 0x1
[SPEW ]   CPU_POWER_MGMT_VR_CONFIG : CepEnable[2] : 0x1

Change-Id: I8908e8b6c995390b559212d456db6ddf984448a3
Signed-off-by: Subrata Banik 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77611
Tested-by: build bot (Jenkins) 
Reviewed-by: Eran Mitrani 
Reviewed-by: Nick Vaccaro 
---
M src/soc/intel/meteorlake/romstage/fsp_params.c
1 file changed, 5 insertions(+), 4 deletions(-)

Approvals:
  Eran Mitrani: Looks good to me, approved
  build bot (Jenkins): Verified
  Nick Vaccaro: Looks good to me, approved

diff --git a/src/soc/intel/meteorlake/romstage/fsp_params.c b/src/soc/intel/meteorlake/romstage/fsp_params.c
index bb5b6e7..36aa11e 100644
--- a/src/soc/intel/meteorlake/romstage/fsp_params.c
+++ b/src/soc/intel/meteorlake/romstage/fsp_params.c
@@ -229,11 +229,12 @@
 {
    /* FastVmode Settings for VR domains */
    for (size_t domain = 0; domain < NUM_VR_DOMAINS; domain++) {
-		m_cfg->CepEnable[domain] = config->cep_enable[domain];
-		if (m_cfg->CepEnable[domain]) {
-			m_cfg->EnableFastVmode[domain] = config->enable_fast_vmode[domain];
-			if (m_cfg->EnableFastVmode[domain])
+		if (config->cep_enable[domain]) {
+			m_cfg->CepEnable[domain] = config->cep_enable[domain];
+			if (config->enable_fast_vmode[domain]) {
+				m_cfg->EnableFastVmode[domain] = config->enable_fast_vmode[domain];
    			m_cfg->IccLimit[domain] = config->fast_vmode_i_trip[domain];
+			}
    	}
    }
 }