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 <[email protected]>
> ---
>  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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