[Intel-gfx] [PATCH 2/4 V2] drm/i915: hdmi detection according to edid header

[Eric Anholt]

On Mon, 2009-07-13 at 17:57 +0800, ling.ma at intel.com wrote:
> According to investigations from windows team ,hw team,
> and our test results on all 4x platofrms available
> (gm45, g45b, q45, g45a, g45c, g41a, and g41), we find
> currently Hot plug live status and Hot plug interrupt
> detection are not reliable, sometime the results from
> the two approaches are contradicts. So we chose edid
> detection for hdmi output, and only read edid header
> to save detection time.
> 
> It fixed freedescktop.org bug #21322
> 
> Signed-off-by: Ma Ling <ling.ma at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_hdmi.c |   54 +++++++-----------------------------
>  1 files changed, 11 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 9e30daa..7c29d2d 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -163,50 +163,28 @@ igdng_hdmi_detect(struct drm_connector *connector)
>  	return intel_hdmi_edid_detect(connector);
>  }
>  
> +/* Valid EDID header has these bytes */
> +static u8 EDID_HEADER[] = { 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00 };
> +
>  static enum drm_connector_status
>  intel_hdmi_detect(struct drm_connector *connector)
>  {
>  	struct drm_device *dev = connector->dev;
> -	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_output *intel_output = to_intel_output(connector);
> -	struct intel_hdmi_priv *hdmi_priv = intel_output->dev_priv;
> -	u32 temp, bit;
> +	u8 edid_header[sizeof(EDID_HEADER)];
> +	int ret;
>  
>  	if (IS_IGDNG(dev))
>  		return igdng_hdmi_detect(connector);
>  
> -	temp = I915_READ(PORT_HOTPLUG_EN);
> -
> -	switch (hdmi_priv->sdvox_reg) {
> -	case SDVOB:
> -		temp |= HDMIB_HOTPLUG_INT_EN;
> -		break;
> -	case SDVOC:
> -		temp |= HDMIC_HOTPLUG_INT_EN;
> -		break;
> -	default:
> -		return connector_status_unknown;
> -	}
> -
> -	I915_WRITE(PORT_HOTPLUG_EN, temp);
> -
> -	POSTING_READ(PORT_HOTPLUG_EN);
> -
> -	switch (hdmi_priv->sdvox_reg) {
> -	case SDVOB:
> -		bit = HDMIB_HOTPLUG_INT_STATUS;
> -		break;
> -	case SDVOC:
> -		bit = HDMIC_HOTPLUG_INT_STATUS;
> -		break;
> -	default:
> -		return connector_status_unknown;
> -	}
> +	ret = drm_do_probe_ddc_edid(intel_output->ddc_bus,
> +				    edid_header, sizeof(EDID_HEADER));
>  
> -	if ((I915_READ(PORT_HOTPLUG_STAT) & bit) != 0)
> -		return intel_hdmi_edid_detect(connector);
> -	else
> +	/*Fail to get edid, return disconnect status*/
> +	if (ret || memcmp(edid_header, EDID_HEADER, sizeof(EDID_HEADER)))
>  		return connector_status_disconnected;
> +
> +	return intel_hdmi_edid_detect(connector);
>  }

Why get a header of the EDID and return disconnected if failed, if you
just go on to re-get the full EDID and return disconnected if it's
failed or non-digital?

-- 
Eric Anholt
eric at anholt.net                         eric.anholt at intel.com


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