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[2/7] efi/earlycon: Fix early printk for wider fonts

Message ID 20200517125754.8934-3-ardb@kernel.org (mailing list archive)
State Not Applicable, archived
Headers show
Series [1/7] efi/libstub: Avoid returning uninitialized data from setup_graphics() | expand

Commit Message

Ard Biesheuvel May 17, 2020, 12:57 p.m. UTC 
From: Dave Young <dyoung@redhat.com>

When I play with terminus fonts I noticed the efi early printk does
not work because the earlycon code assumes font width is 8.

Here add the code to adapt with larger fonts.  Tested with all kinds
of kernel built-in fonts on my laptop. Also tested with a local draft
patch for 14x28 !bold terminus font.

Signed-off-by: Dave Young <dyoung@redhat.com>
Link: https://lore.kernel.org/r/20200412024927.GA6884@dhcp-128-65.nay.redhat.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/earlycon.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c
index 5d4f84781aa0..a52236e11e5f 100644
--- a/drivers/firmware/efi/earlycon.c
+++ b/drivers/firmware/efi/earlycon.c
@@ -114,14 +114,16 @@  static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
 	const u32 color_black = 0x00000000;
 	const u32 color_white = 0x00ffffff;
 	const u8 *src;
-	u8 s8;
-	int m;
+	int m, n, bytes;
+	u8 x;
 
-	src = font->data + c * font->height;
-	s8 = *(src + h);
+	bytes = BITS_TO_BYTES(font->width);
+	src = font->data + c * font->height * bytes + h * bytes;
 
-	for (m = 0; m < 8; m++) {
-		if ((s8 >> (7 - m)) & 1)
+	for (m = 0; m < font->width; m++) {
+		n = m % 8;
+		x = *(src + m / 8);
+		if ((x >> (7 - n)) & 1)
 			*dst = color_white;
 		else
 			*dst = color_black;