Re: [PATCH v2] drm/i915: Restrict usage of live status check

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

On Wed, Apr 20, 2016 at 05:42:51PM +0530, Shashank Sharma wrote:
> 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 regression added by patch:
> 	'commit 237ed86c693d ("drm/i915: Check live status before reading edid")'
> 
> ===
> V2
> ===
> Ville:
> - Add live_status =  true in the end of delay loop.
> 
> Jani:
> - Initialize bool live_status with false;
> - Change regression reference in the commit message.
> - Use dev_priv instead of dev
> - Move declaration of try at the loop
> 
> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_hdmi.c | 31 ++++++++++++++++++++++++-------
>  1 file changed, 24 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index b199ede..98f5ae0 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1398,22 +1398,39 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
>  	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
>  	struct drm_i915_private *dev_priv = to_i915(connector->dev);
>  	bool live_status = false;
> -	unsigned int try;
>  
>  	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
>  		      connector->base.id, connector->name);
>  
>  	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
>  
> -	for (try = 0; !live_status && try < 9; try++) {
> -		if (try)
> -			msleep(10);
> -		live_status = intel_digital_port_connected(dev_priv,
> +	/*
> +	* Live status check for HDMI detection is not very
> +	* reliable on older platforms. So insist the live
> +	* status check for EDID read from VLV onwards.
> +	*/
> +	if (INTEL_INFO(dev_priv)->gen >= 7 && !IS_IVYBRIDGE(dev_priv)) {
> +		unsigned int try;
> +
> +		for (try = 0; !live_status && try < 9; try++) {
> +			if (try)
> +				msleep(10);
> +			live_status = intel_digital_port_connected(dev_priv,
>  				hdmi_to_dig_port(intel_hdmi));
> +		}
>  	}
>  
> -	if (!live_status)
> -		DRM_DEBUG_KMS("Live status not up!");
> +	if (!live_status) {
> +		/*
> +		* TODO: Replace this with some magic code.
> +		* Even after giving enough delay, live status is not up.
> +		* Lets read EDID and decide if HDMI is available. We
> +		* have to do this not to break old platforms, but ideally
> +		* should read EDID only when live_status reg allows us.
> +		*/
> +		DRM_DEBUG_KMS("Live status down, making it up\n");
> +		live_status = true;
> +	}

Hmm. This is still not what I suggested earlier. Was there some problem
with my idea?

>  
>  	intel_hdmi_unset_edid(connector);
>  
> -- 
> 1.9.1

-- 
Ville Syrjälä
Intel OTC
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