Re: [PATCH 2/2] drm/i915: Restrict usage of live status check

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 11 Mar 2016, Shashank Sharma <shashank.sharma@intel.com> wrote:
> [ text/plain ]
> This patch restricts usage of live status check for HDMI detection.
> While testing certain (monitor + cable) combinations with various
> intel  platforms, it seems that live status register is not reliable
> on some older devices. So limit the live_status check from VLV onwards.
>
> This fixes a regression introduced in:
> commit 237ed86c693d8a8e4db476976aeb30df4deac74b
> Author: Sonika Jindal <sonika.jindal@intel.com>
> Date:   Tue Sep 15 09:44:20 2015 +0530
> drm/i915: Check live status before reading edid

This is in v4.4, which means the fix will need to be backported too, so
please send a patch fixing the bug *first*, instead of depending on an
optimization patch.

BR,
Jani.


>
> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_hdmi.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index b523a2f..ca1fb57 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1397,6 +1397,7 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
>  	enum drm_connector_status status;
>  	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
>  	struct drm_i915_private *dev_priv = to_i915(connector->dev);
> +	struct drm_device *dev = connector->dev;
>  	bool live_status = true;
>  	unsigned int try = 8;
>  
> @@ -1404,14 +1405,21 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
>  		      connector->base.id, connector->name);
>  
>  	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
> -	live_status = intel_digital_port_connected(dev_priv,
> -		hdmi_to_dig_port(intel_hdmi));
> -	while (!live_status && try--) {
> -		msleep(10);
> +
> +	/*
> +	* The live status register doesn't work reliably with certain
> +	* cables/monitors, on old platforms. So restrict the live status
> +	* check to be applied from VLV onwards.
> +	*/
> +	if (INTEL_INFO(dev)->gen >= 7 && !IS_IVYBRIDGE(dev)) {
>  		live_status = intel_digital_port_connected(dev_priv,
>  			hdmi_to_dig_port(intel_hdmi));
> +		while (!live_status && try--) {
> +			msleep(10);
> +			live_status = intel_digital_port_connected(dev_priv,
> +				hdmi_to_dig_port(intel_hdmi));
> +		}
>  	}
> -
>  	intel_hdmi_unset_edid(connector);
>  
>  	if (intel_hdmi_set_edid(connector, live_status)) {

-- 
Jani Nikula, Intel Open Source Technology Center
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