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U-Boot x86: Avoid clearing the VESA display

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This is a patch from Simon Glass. U-Boot clears the display
when it starts up, but was asking the VESA driver to do the
same, needlessly; this patch avoids the latter.

A further patch is also included, which provides a better
message when jumping into long mode on the SPL (64-bit) target,
dumping it on the serial console instead of using printf.

Signed-off-by: Leah Rowe <leah@libreboot.org>
This commit is contained in:
Leah Rowe
2024-11-20 15:44:35 +00:00
parent 32dced8cd8
commit 02e66ae01a
4 changed files with 126 additions and 0 deletions
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config/u-boot/x86_64/patches/0002-x86-Avoid-clearing-the-VESA-display.patch
+34
View File
@@ -0,0 +1,34 @@
From a6b9e69a21970951252419b5b5fa9c04fabbf1a4 Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Tue, 12 Nov 2024 06:59:02 -0700
Subject: [PATCH 1/2] x86: Avoid clearing the VESA display
U-Boot clears the display when it starts up, so there is no need to ask
the VESA driver to do this. Fix this and add a comment explaining the
flags.
Signed-off-by: Simon Glass <sjg@chromium.org>
---
arch/x86/lib/bios.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/lib/bios.c b/arch/x86/lib/bios.c
index 03f7360032..374f4f20b8 100644
--- a/arch/x86/lib/bios.c
+++ b/arch/x86/lib/bios.c
@@ -228,7 +228,11 @@ static void vbe_set_graphics(int vesa_mode, struct vesa_state *mode_info)
{
unsigned char *framebuffer;
- mode_info->video_mode = (1 << 14) | vesa_mode;
+ /*
+ * bit 14 is linear-framebuffer mode
+ * bit 15 means don't clear the display
+ */
+ mode_info->video_mode = (1 << 14) | (1 << 15) | vesa_mode;
vbe_get_mode_info(mode_info);
framebuffer = (unsigned char *)(ulong)mode_info->vesa.phys_base_ptr;
--
2.39.5