On Fri, 11 Mar 2016, Shashank Sharma <shashank.sharma@xxxxxxxxx> 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@xxxxxxxxx>
> 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@xxxxxxxxx>
> ---
> 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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