[Intel-gfx] [PATCH v2 2/6] drm/i915/dp: Restrict link retrain workaround to external monitors

[Lyude Paul]

Reviewed-by: Lyude Paul <lyude at redhat.com>

On Mon, 2018-09-24 at 15:45 -0700, Dhinakaran Pandiyan wrote:
> Commit '3cf71bc9904d ("drm/i915: Re-apply "Perform link quality check,
> unconditionally during long pulse"")' applies a work around for sinks
> that don't signal link loss. The work around does not need to have to be
> that broad as the issue was seen with only one particular monitor; limit
> this only for external displays as eDP features like PSR turn off the link
> and the driver ends up retraining the link seeeing that link is not
> synchronized.
> 
> Cc: Lyude Paul <lyude at redhat.com>
> Cc: Jan-Marek Glogowski <glogow at fbihome.de>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link quality check,
> unconditionally during long pulse"")
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c
> index 34c561011e7a..6130d05d8b88 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -5072,12 +5072,13 @@ intel_dp_long_pulse(struct intel_connector
> *connector,
>  		 */
>  		status = connector_status_disconnected;
>  		goto out;
> -	} else {
> -		/*
> -		 * Some external monitors do not signal loss of link
> -		 * synchronization with an IRQ_HPD, so force a link status
> -		 * check.
> -		 */
> +	}
> +
> +	/*
> +	 * Some external monitors do not signal loss of link synchronization
> +	 * with an IRQ_HPD, so force a link status check.
> +	 */
> +	if (!intel_dp_is_edp(intel_dp)) {
>  		struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)-
> >base;
>  
>  		intel_dp_retrain_link(encoder, ctx);
-- 
Cheers,
	Lyude Paul