[PATCH] drm/i915/hdmi: Fix weak connector detection
Ville Syrjälä
ville.syrjala at linux.intel.com
Fri Apr 1 14:47:47 UTC 2016
On Thu, Mar 31, 2016 at 05:55:03PM -0300, Ezequiel Garcia wrote:
> Currently, our implementation of drm_connector_funcs.detect is
> based on getting a valid EDID.
>
> This requirement makes the driver fail to detect connected
> connectors in case of EDID corruption, which prevents from falling
> back to modes provided by builtin or user-provided EDIDs.
So why are you getting corrupted EDIDs?
>
> Let's fix this by improving the detection, with a DDC probe,
> if the current EDID-based detection failed.
>
> Note that a better way of dealing with this could calling
> drm_probe_ddc in drm_connector_funcs.detect, and do the
> EDID full reading and parsing in drm_connector_helper_funcs.get_modes,
> when it's actually needed.
>
> However, this would be more invasive and thus more error-prone.
> The current commit is an attempt to get some uninvasive fix,
> and allow for easier backporting.
>
> Signed-off-by: Ezequiel Garcia <ezequiel at vanguardiasur.com.ar>
> ---
> drivers/gpu/drm/i915/intel_hdmi.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index a0d8daed2470..c079206e6681 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1428,6 +1428,20 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
> } else
> status = connector_status_disconnected;
>
> + /*
> + * The above call to intel_hdmi_set_edid() checked for a valid EDID.
> + * However, the EDID can get corrupted for several reasons, resulting
> + * in a disconnected status despite the connector being connected.
> + * Hence, let's try one more time, by only probing the DDC.
> + *
> + * This allows the DRM core to fallback to builtin or user-provided
> + * EDID firmware, e.g. in drm_helper_probe_single_connector_modes.
> + */
> + if (status == connector_status_disconnected)
> + if (drm_probe_ddc(intel_gmbus_get_adapter(dev_priv,
> + intel_hdmi->ddc_bus)))
> + status = connector_status_connected;
> +
> intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
>
> return status;
> --
> 2.7.0
>
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--
Ville Syrjälä
Intel OTC
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