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soc/intel/fatcat: Override FSP-M UART MMIO for GFX PEIM debug

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This patch overrides the FSP-M UART MMIO base address to ensure the FSP
GFX PEIM can output debug console messages when required.

Currently, the default UART MMIO base used by FSP-M/S might not be the
intended console UART for debug output in boot stages, particularly for
the GFX PEIM. By overriding it with the value derived from
`CONFIG_UART_FOR_CONSOLE` when either `PcdSerialDebugLevel` or
`SerialDebugMrcLevel` is non-zero, we ensure that debug logs are
directed to the configured console.

This change is crucial for debugging issues within the GFX PEIM
initialization process.

BUG=b:380375181
TEST=Verified that enabling FSP debug tokens after this change allows
viewing debug output from the GFX PEIM during display initialization.

Steps to reproduce:

1. Flash an AP FW image (`image.fatcat.serial.bin`).
2. Observe the absence of debug output from the GFX PEIM during display
   initialization.
3. Dynamically enable the FSP debug token using

```
sudo cbfstool image-fatcat.serial.bin add-int -i 3 -n option/fsp_pcd_debug_level
```
4. Flash the modified AP FW image.
5. Observe debug output from the GFX PEIM during display initialization

```
[INFO]:[IsGraphicsDeviceSupported()]...
[INFO]:[GetVbtStartAddress()]
```

Change-Id: I835ef75cb3046217127823c92f708bfe4f3ff741
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/87318
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Jayvik Desai <jayvik@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Alok Agarwal <alok.agarwal@intel.com>
Reviewed-by: Jérémy Compostella <jeremy.compostella@intel.com>
This commit is contained in:
Subrata Banik 2025-04-15 17:12:12 +05:30
commit eabe395778
1 changed files with 4 additions and 1 deletions
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5
src/soc/intel/pantherlake/romstage/fsp_params.c
View file

@ -359,8 +359,11 @@ static void fsp_control_log_level(FSPM_UPD *mupd, bool is_enabled)
}
/* Set Event Handler if log-level is non-zero */
if (m_cfg->PcdSerialDebugLevel || m_cfg->SerialDebugMrcLevel)
if (m_cfg->PcdSerialDebugLevel || m_cfg->SerialDebugMrcLevel) {
arch_upd->FspEventHandler = (uintptr_t)((FSP_EVENT_HANDLER *)fsp_debug_event_handler);
/* Override SerialIo Uart default MMIO resource if log-level is non-zero */
m_cfg->SerialIoUartDebugMmioBase = UART_BASE(CONFIG_UART_FOR_CONSOLE);
}
}
static void fill_fsp_event_handler(FSPM_UPD *mupd)