linux-kernel - Re: [Intel-gfx] [PATCH 3/7] drm/i915: Treat PCH eDP like DP in most places

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Message-ID: <yunobwuwiv7.fsf@aiko.keithp.com>
Date:	Wed, 02 Nov 2011 10:10:20 -0700
From:	Keith Packard <keithp@...thp.com>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 3/7] drm/i915: Treat PCH eDP like DP in most places

On Wed, 2 Nov 2011 09:20:19 -0700, Jesse Barnes <jbarnes@...tuousgeek.org> wrote:

> But I was curious about this hunk:
> 
> @@ -766,10 +766,10 @@ intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,
>  			continue;
>  
>  		intel_dp = enc_to_intel_dp(encoder);
> -		if (intel_dp->base.type == INTEL_OUTPUT_DISPLAYPORT) {
> +		if (intel_dp->base.type == INTEL_OUTPUT_DISPLAYPORT || is_pch_edp(intel_dp)) {
>  			lane_count = intel_dp->lane_count;
>  			break;
> -		} else if (is_edp(intel_dp)) {
> +		} else if (is_cpu_edp(intel_dp)) {
>  			lane_count = dev_priv->edp.lanes;
>  			break;
>  		}
> 
> I guess this means we can't trust the BIOS settings for PCH eDP?

I'm pretty sure this isn't the right place to look at this value in any
case; we're setting the m/n ratios after already deciding how many lanes
to use. Getting this wrong means sending the wrong timing to the
monitor, not setting a different mode.

In any case, my AIO box sets the BIOS value to 1, when it needs 2 lanes
for the mode it uses.

-- 
keith.packard@...el.com

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