sm501fb: clear framebuffer memory and palette
PATCH RESEND 1/1 sm501fb: clear framebuffer memory and palette
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.
---
This is the same patch that was sent to linux-fbdev-devel on 20071228.
drivers/video/sm501fb.c | 8 ++++++++ 1 file changed, 8 insertions(+)
drivers/video/sm501fb.c +8 -0
@@ -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 );
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Quoted 11 lines · Magnus Damm
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.
Quoted 5 lines
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.
Can you please add a no-clear-on-init flag incase people do not want their framebuffers cleared.
Quoted 41 lines
Signed-off-by Magnus Damm <[email protected]>---
This is the same patch that was sent to linux-fbdev-devel on 20071228.
drivers/video/sm501fb.c | 8 ++++++++ 1 file changed, 8 insertions(+)drivers/video/sm501fb.c +8
-1@@ -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 ); -------------------------------------------------------------------------This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008.
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