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soc/mediatek/common: Conditionally set up framebuffer

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To save memory, only allocate and configure the framebuffer when display
output is required during boot.

This is achieved by:
1. Making the `framebuffer` memory region optional.
2. Guarding the framebuffer's uncached MMU configuration with a
   `display_init_required()` check.

This ensures the framebuffer is prepared only when needed, saving
memory on boot paths that do not require display.

BUG=b:319511268
BRANCH=none
TEST=emerge-rauru coreboot

Change-Id: I3808031160e421de7c21f585f4b79d42bfddccc4
Signed-off-by: Yidi Lin <yidilin@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89541
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Yidi Lin 2025-10-09 00:38:12 +08:00
commit 0ff213d711
3 changed files with 12 additions and 2 deletions
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2
src/include/symbols.h
View file

@ -75,7 +75,7 @@ DECLARE_REGION(ttb)
DECLARE_OPTIONAL_REGION(ttb_subtables)
DECLARE_REGION(dma_coherent)
DECLARE_REGION(soc_registers)
DECLARE_REGION(framebuffer)
DECLARE_OPTIONAL_REGION(framebuffer)
DECLARE_REGION(pdpt)
DECLARE_OPTIONAL_REGION(opensbi)
DECLARE_OPTIONAL_REGION(bl31)

7
src/soc/mediatek/common/display.c
View file

@ -11,6 +11,7 @@
#include <soc/dsi.h>
#include <soc/mtcmos.h>
#include <stdio.h>
#include <symbols.h>
static struct panel_serializable_data *get_mipi_cmd_from_cbfs(struct panel_description *desc)
{
@ -70,6 +71,7 @@ int mtk_display_init(void)
struct fb_info *info;
const char *name;
struct panel_description *panel = get_active_panel();
uintptr_t fb_addr;
if (!panel || panel->disp_path == DISP_PATH_NONE) {
printk(BIOS_ERR, "%s: Failed to get the active panel\n", __func__);
@ -143,7 +145,10 @@ int mtk_display_init(void)
}
}
info = fb_new_framebuffer_info_from_edid(&edid, (uintptr_t)0);
fb_addr = (REGION_SIZE(framebuffer)) ? (uintptr_t)_framebuffer : 0;
info = fb_new_framebuffer_info_from_edid(&edid, fb_addr);
if (info)
fb_set_orientation(info, panel->orientation);

5
src/soc/mediatek/common/mmu_operations.c
View file

@ -1,6 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#include <arch/mmu.h>
#include <bootmode.h>
#include <symbols.h>
#include <soc/emi.h>
#include <soc/mmu_operations.h>
@ -51,6 +52,10 @@ void mtk_mmu_after_dram(void)
mmu_config_range(_dram_dma, REGION_SIZE(dram_dma), NONSECURE_UNCACHED_MEM);
if (display_init_required())
mmu_config_range(_framebuffer, REGION_SIZE(framebuffer),
NONSECURE_UNCACHED_MEM);
mtk_soc_after_dram();
}