Re: [PATCH 4/4] drm/i915: Allow HDMI+HDMI cloning on g4x

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Mar 03, 2014 at 04:15:31PM +0200, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> BSpec is a bit unclear whether HDMI+HDMI cloning should work on g4x.
> Tests on real hardware say that it does. Since g4x can't send
> infoframes to more than one HDMI port anyway, we don't lose anything
> by allow it.
> 
> For PCH platforms BSpec explicitly forbids HDMI+HDMI cloning.
> 
> Whether HDMI+HDMI cloning might also work on VLV is a bit unclear, but
> since we'd at least lose the capability of sending infoframes to more
> than one cloned HDMI port, it doesn't seem like a good idea to allow it.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73850
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_hdmi.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 9dacb33..4eb30d8 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1316,6 +1316,13 @@ void intel_hdmi_init(struct drm_device *dev, int hdmi_reg, enum port port)
>  	intel_encoder->type = INTEL_OUTPUT_HDMI;
>  	intel_encoder->crtc_mask = (1 << 0) | (1 << 1) | (1 << 2);
>  	intel_encoder->cloneable = 1 << INTEL_OUTPUT_ANALOG;
> +	/*
> +	 * BSpec is unclear about HDMI+HDMI cloning on g4x, but it seems
> +	 * to work on real hardware. And since g4x can send infoframes to
> +	 * only one port anyway, nothing is lost by allowing it.
> +	 */
> +	if (IS_G4X(dev))

Why restrict this? The per-encoder infoframe setup should dtrt everywhere
else I hope ...
-Daniel

> +		intel_encoder->cloneable |= 1 << INTEL_OUTPUT_HDMI;
>  
>  	intel_dig_port->port = port;
>  	intel_dig_port->hdmi.hdmi_reg = hdmi_reg;
> -- 
> 1.8.3.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch