Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1416211

[PATCH] [efifb] Fix 16 color palette entry calculation

Show all headers | View raw

When using efifb with a 16-bit (5:6:5) visual, fbcon's text is rendered
in the wrong colors - e.g. text gray (#aaaaaa) is rendered as green
(#50bc50) and neighboring pixels have slightly different values
(such as #50bc78).

The reason is that fbcon loads its 16 color palette through
efifb_setcolreg(), which in turn calculates a 32-bit value to write
into memory for each palette index.
Until now, this code could only handle 8-bit visuals and didn't mask
overlapping values when ORing them.

With this patch, fbcon displays the correct colors when a qemu VM is
booted in 16-bit mode (in GRUB: "set gfxpayload=800x600x16").

Signed-off-by: Max Staudt <mstaudt@suse.de>
---
 drivers/video/fbdev/efifb.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
index 924bad4..37a37c4 100644
--- a/drivers/video/fbdev/efifb.c
+++ b/drivers/video/fbdev/efifb.c
@@ -50,9 +50,9 @@ static int efifb_setcolreg(unsigned regno, unsigned red, unsigned green,
 		return 1;
 
 	if (regno < 16) {
-		red   >>= 8;
-		green >>= 8;
-		blue  >>= 8;
+		red   >>= 16 - info->var.red.length;
+		green >>= 16 - info->var.green.length;
+		blue  >>= 16 - info->var.blue.length;
 		((u32 *)(info->pseudo_palette))[regno] =
 			(red   << info->var.red.offset)   |
 			(green << info->var.green.offset) |
-- 
2.6.6

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH] [efifb] Fix 16 color palette entry calculation Max Staudt <mstaudt@suse.de> - 2016-06-07 15:50 +0200
  Re: [PATCH] [efifb] Fix 16 color palette entry calculation Greg KH <gregkh@linuxfoundation.org> - 2016-06-07 18:50 +0200
  Re: [PATCH] [efifb] Fix 16 color palette entry calculation Peter Jones <pjones@redhat.com> - 2016-06-07 19:30 +0200
    Re: [PATCH] [efifb] Fix 16 color palette entry calculation Matt Fleming <matt@codeblueprint.co.uk> - 2016-06-08 14:50 +0200
      Re: [PATCH] [efifb] Fix 16 color palette entry calculation Tomi Valkeinen <tomi.valkeinen@ti.com> - 2016-06-10 13:40 +0200

csiph-web