Re: [PATCH v2 03/10] drm/i915: Check VBT for CRT port presence on HSW/BDW

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Dec 01, 2015 at 06:07:09PM +0200, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Unfortunatey there appear to quite a few HSW/BDW machines (eg.
> NUCs, Brix Pro) in the wild with LPT/WPT-H but non-working FDI.
> FDI training fails every single time on these machines. Dunno,
> maybe they just didn't bother wiring it up or something?
> 
> Unfortunately all the fuse bits and whatnot are telling us that
> the CRT connector is present. And so what we get from this is tons
> of false positives from the CI systems due to VGA connector forcing.
> 
> I've not found any way to detect this purely from hardware, so we
> have to resort to looking at the VBT int_crt_support bit. We used
> to check this bit on all platforms, but that broke all the old
> machines, so the check was then restricted to VLV only in
> commit 84b4e042c470 ("drm/i915: only apply crt_present check on VLV")
> 
> Considering HSW and VLV VBT probably got defined around the same time,
> it should be reasonably safe to assume that the bits is sane for
> HSW/BDW as well. At least I have one copy of some VBT spec here that
> says it's meant for both VLV and HSW, and it knows about the bit
> (lists it being valid from version 155 onwards). Also I have two
> desktop machines with actual CRT ports and both have
> int_crt_support==1 in their VBTs.
> 
> v2: Move the platform checks into the VBT parsing code
>     Also check that the VBT version is at least 155
> 
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93190

> ---
>  drivers/gpu/drm/i915/intel_bios.c    | 5 ++++-
>  drivers/gpu/drm/i915/intel_display.c | 2 +-
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index ce82f9c7df24..070470fe9a91 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -356,7 +356,10 @@ parse_general_features(struct drm_i915_private *dev_priv,
>  	general = find_section(bdb, BDB_GENERAL_FEATURES);
>  	if (general) {
>  		dev_priv->vbt.int_tv_support = general->int_tv_support;
> -		dev_priv->vbt.int_crt_support = general->int_crt_support;
> +		/* int_crt_support can't be trusted on earlier platforms */
> +		if (bdb->version >= 155 &&
> +		    (HAS_DDI(dev_priv) || IS_VALLEYVIEW(dev_priv)))
> +			dev_priv->vbt.int_crt_support = general->int_crt_support;
>  		dev_priv->vbt.lvds_use_ssc = general->enable_ssc;
>  		dev_priv->vbt.lvds_ssc_freq =
>  			intel_bios_ssc_frequency(dev, general->ssc_freq);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index e80387dd6582..68822395914b 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -14263,7 +14263,7 @@ static bool intel_crt_present(struct drm_device *dev)
>  	if (HAS_DDI(dev) && I915_READ(DDI_BUF_CTL(PORT_A)) & DDI_A_4_LANES)
>  		return false;
>  
> -	if (IS_VALLEYVIEW(dev) && !dev_priv->vbt.int_crt_support)
> +	if (!dev_priv->vbt.int_crt_support)
>  		return false;
>  
>  	return true;
> -- 
> 2.4.10
> 
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-- 
Ville Syrjälä
Intel OTC
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