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authorMagnus Damm <magnus.damm@gmail.com>2008-02-06 04:39:25 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-06 13:41:16 -0500
commitb1230ee50a9903a987feaad767fb71e2fd173894 (patch)
treeb0c2ddb9ae3c180361ebcef571a611a801b80dab /drivers
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')
-rw-r--r--drivers/video/sm501fb.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/video/sm501fb.c b/drivers/video/sm501fb.c
index e1d6085bc347..8c39e4d5b08f 100644
--- a/drivers/video/sm501fb.c
+++ b/drivers/video/sm501fb.c
@@ -1276,6 +1276,7 @@ static int sm501fb_start(struct sm501fb_info *info,
1276{ 1276{
1277 struct resource *res; 1277 struct resource *res;
1278 struct device *dev; 1278 struct device *dev;
1279 int k;
1279 int ret; 1280 int ret;
1280 1281
1281 info->dev = dev = &pdev->dev; 1282 info->dev = dev = &pdev->dev;
@@ -1337,6 +1338,13 @@ static int sm501fb_start(struct sm501fb_info *info,
1337 1338
1338 info->fbmem_len = (res->end - res->start)+1; 1339 info->fbmem_len = (res->end - res->start)+1;
1339 1340
1341 /* clear framebuffer memory - avoids garbage data on unused fb */
1342 memset(info->fbmem, 0, info->fbmem_len);
1343
1344 /* clear palette ram - undefined at power on */
1345 for (k = 0; k < (256 * 3); k++)
1346 writel(0, info->regs + SM501_DC_PANEL_PALETTE + (k * 4));
1347
1340 /* enable display controller */ 1348 /* enable display controller */
1341 sm501_unit_power(dev->parent, SM501_GATE_DISPLAY, 1); 1349 sm501_unit_power(dev->parent, SM501_GATE_DISPLAY, 1);
1342 1350