From: Magnus D. <mag...@gm...> - 2007-12-28 05:57:41
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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 <da...@ig...> --- Applies to 2.6.24-rc6. drivers/video/sm501fb.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- 0002/drivers/video/sm501fb.c +++ work/drivers/video/sm501fb.c 2007-12-27 13:24:20.000000000 +0900 @@ -1264,6 +1264,7 @@ static int sm501fb_start(struct sm501fb_ { struct resource *res; struct device *dev; + int k; int ret; info->dev = dev = &pdev->dev; @@ -1325,6 +1326,13 @@ static int sm501fb_start(struct sm501fb_ 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); |
From: Paul M. <le...@li...> - 2008-01-10 02:53:59
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On Fri, Dec 28, 2007 at 02:51:13PM +0900, Magnus Damm wrote: > sm501fb: control panel pin usage with platform data flags > > This patch makes it possible to control panel pins usage with flags passed > from the platform data. Without this patch the sm501fb driver always controls > the VBIASEN and FPEN pins. The polarity and use of these pins are very platform > specific, so this patch introduces the flags SM501FB_FLAG_PANEL_USE_VBIASEN > and SM501FB_FLAG_PANEL_USE_FPEN which enable the use of these pins. > > This patch is needed to support the a Sharp LQ104V1DG21 lcd panel on SuperH > platforms such as R2D-1 and R2D-PLUS boards. Letting the sm501fb driver control > the FPEN and VBIASEN pins like today just results in lcd panel flicker. > > Signed-off-by: Magnus Damm <da...@ig...> On Fri, Dec 28, 2007 at 02:55:52PM +0900, Magnus Damm wrote: > 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 <da...@ig...> There hasn't been any updates or objections to these, and we do still need them. Andrew, can you roll these in to -mm? |