[PATCH] nvidiafb: Fix reversed DDC port

[PATCH] nvidiafb: Fix reversed DDC port

[Antonino A. Daplas]

From: Petr Vandrovec <vandrove@vc.cvut.cz>

After I added some debugging printks I've found that code became a bit
confused because it believed that primary monitor is 1920x540, but later
it found in CRTC0's registers that panel size is 1920x1200 (Windows also
agree that 1920x1200 is primary monitor, and 1920x1080i secondary one).

When I applied attached patch then my monitor became as happy as it was
before I connected HDMI cable to secondary output.

Signed-off-by: Petr Vandrovec <vandrove@vc.cvut.cz>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
---

 drivers/video/nvidia/nv_i2c.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/nvidia/nv_i2c.c b/drivers/video/nvidia/nv_i2c.c
index b91d404..bcde013 100644
--- a/drivers/video/nvidia/nv_i2c.c
+++ b/drivers/video/nvidia/nv_i2c.c
@@ -131,10 +131,10 @@ void nvidia_create_i2c_busses(struct nvi
 	par->chan[1].par = par;
 	par->chan[2].par = par;
 
-	par->chan[0].ddc_base = 0x3e;
+	par->chan[0].ddc_base = 0x36;
 	nvidia_setup_i2c_bus(&par->chan[0], "nvidia #0");
 
-	par->chan[1].ddc_base = 0x36;
+	par->chan[1].ddc_base = 0x3e;
 	nvidia_setup_i2c_bus(&par->chan[1], "nvidia #1");
 
 	par->chan[2].ddc_base = 0x50;


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Re: [PATCH] nvidiafb: Fix reversed DDC port

[Dave Airlie]

> After I added some debugging printks I've found that code became a bit
> confused because it believed that primary monitor is 1920x540, but later
> it found in CRTC0's registers that panel size is 1920x1200 (Windows also
> agree that 1920x1200 is primary monitor, and 1920x1080i secondary one).
>
> When I applied attached patch then my monitor became as happy as it was
> before I connected HDMI cable to secondary output.
>

I don't think this will do much except break other peoples cards,
different nvidia cards map the i2c to outputs differently, the correct
way to fix it is to read a table in the BIOS called the DCB table (for
NV4x and above...) guess what? we don't know how to do that properly
because nvidia are very unfriendly...

Dave.

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Re: [PATCH] nvidiafb: Fix reversed DDC port

[Antonino A. Daplas]

On Mon, 2007-04-02 at 09:07 +1000, Dave Airlie wrote:
> > After I added some debugging printks I've found that code became a bit
> > confused because it believed that primary monitor is 1920x540, but later
> > it found in CRTC0's registers that panel size is 1920x1200 (Windows also
> > agree that 1920x1200 is primary monitor, and 1920x1080i secondary one).
> >
> > When I applied attached patch then my monitor became as happy as it was
> > before I connected HDMI cable to secondary output.
> >
> 
> I don't think this will do much except break other peoples cards,
> different nvidia cards map the i2c to outputs differently, the correct
> way to fix it is to read a table in the BIOS called the DCB table (for
> NV4x and above...) guess what? we don't know how to do that properly
> because nvidia are very unfriendly...
> 

True. The port assignment does not matter for a single display, or
dual-displays with different output types, as nvidiafb and nv has code
that matches the EDID output to the monitor type. 

If nvidia is not consistent with the port assignment, and there is no
sane way of determining this, the best hack we can do is a boot option.

Anyway, Petr's patch is still 'correct', because, in relation with X's
nv driver, the ports are indeed reversed :-)

Tony 



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