Re: [PATCH 1/2] ARM: tegra: paz00: Add host1x support

[Thierry Reding <thierry.reding-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org>]

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On Fri, Nov 16, 2012 at 03:36:04PM -0700, Stephen Warren wrote:
> On 11/16/2012 03:20 PM, Marc Dietrich wrote:
> > This adds host1x support which includes HDMI and LVDS support.
> 
> > diff --git a/arch/arm/boot/dts/tegra20-paz00.dts b/arch/arm/boot/dts/tegra20-paz00.dts
> 
> > +	host1x {
> 
> The position of this node in tegra20-paz00.dts doesn't match the order
> from tegra20.dtsi.
> 
> > +		dc@54200000 {
> > +			rgb {
> > +				status = "okay";
> > +				nvidia,ddc-i2c-bus = <&lvds_ddc>;
> > +			};
> > +		};
> > +
> > +		hdmi {
> > +			status = "okay";
> > +			vdd-supply = <&hdmi_vdd_reg>;
> > +			pll-supply = <&hdmi_pll_reg>;
> > +			nvidia,ddc-i2c-bus = <&hdmi_ddc>;
> > +			nvidia,hpd-gpio = <&gpio 111 0>; /* PN7 */
> > +		};
> 
> I think we shouldn't enable HDMI on Paz00 yet; tegradrm has an issue
> where if two outputs are active, with different display timings (which
> is almost guaranteed), both outputs send the wrong signal timing. The
> easiest WAR for now is to only enable one output per board.

I don't think the timings are the problem. At least in the cases where
I've seen this problem, LVDS was still working fine, only the contents
were "skewed". The most likely reason for that would be a wrong stride
programmed for the smaller display.

But yes, I agree that for now we should keep only a single output
enabled to work around that issue. Unless I get completely swamped with
other stuff I expect to fix that before the final 3.8, but better safe
than sorry.

Thierry

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