path: root/drivers/video/sm501fb.c
diff options
authorMagnus Damm <magnus.damm@gmail.com>2008-02-06 01:39:25 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-06 10:41:16 -0800
commitb1230ee50a9903a987feaad767fb71e2fd173894 (patch)
treeb0c2ddb9ae3c180361ebcef571a611a801b80dab /drivers/video/sm501fb.c
parentdfcffa467b4112fa6f1631c9d6bf7759c3bbe75a (diff)
sm501fb: clear framebuffer memory and palette
Avoid displaying garbage on unused framebuffers. For most users a single framebuffer is used together with fbcon. sm501fb supports two framebuffers where one often is assigned to fbcon and the other one is left unused during the boot. The problem here is that framebuffers not in use by fbcon happen to display garbage. This can easily be solved by making sure that framebuffer memory and palette ram are cleared. The problem can be observed by using looking at the panel output (fb1) after booting the kernel with fbcon on crt (fb0). This is the default configuration. It's also possible to watch the garbage on the crt framebuffer by passing "fbcon=map:1" on the kernel cmdline. This will assign fbcon to the panel (fb1) and leave the crt (fb0) unused. Signed-off-by: Magnus Damm <damm@igel.co.jp> Cc: "Antonino A. Daplas" <adaplas@pol.net> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ben Dooks <ben-linux@fluff.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/video/sm501fb.c')
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/video/sm501fb.c b/drivers/video/sm501fb.c
index e1d6085bc34..8c39e4d5b08 100644
--- a/drivers/video/sm501fb.c
+++ b/drivers/video/sm501fb.c
@@ -1276,6 +1276,7 @@ static int sm501fb_start(struct sm501fb_info *info,
struct resource *res;
struct device *dev;
+ int k;
int ret;
info->dev = dev = &pdev->dev;
@@ -1337,6 +1338,13 @@ static int sm501fb_start(struct sm501fb_info *info,
info->fbmem_len = (res->end - res->start)+1;
+ /* clear framebuffer memory - avoids garbage data on unused fb */
+ memset(info->fbmem, 0, info->fbmem_len);
+ /* clear palette ram - undefined at power on */
+ for (k = 0; k < (256 * 3); k++)
+ writel(0, info->regs + SM501_DC_PANEL_PALETTE + (k * 4));
/* enable display controller */
sm501_unit_power(dev->parent, SM501_GATE_DISPLAY, 1);