On Wed, Aug 1, 2018 at 11:41 AM, Harry Wentland <harry.wentland at amd.com> wrote:
> [Why]
> Some boards seem to have a problem where HPD is high on HDMI even though
> no display is connected. We don't want to report these as connected. DP
> spec still requires us to report DP displays as connected when HPD is
> high but we can't read the EDID in order to go to fail-safe mode.
>
> [How]
> If connector_signal is not DP abort detection if we can't retrieve the
> EDID.
>
> Signed-off-by: Harry Wentland <harry.wentland at amd.com>
Mention the bug report(s) in the commit messages. Besides the recent
one, I think there is another one from a while back about an HDMI port
showing up as connected.
Acked-by: Alex Deucher <alexander.deucher at amd.com>
> ---
> drivers/gpu/drm/amd/display/dc/core/dc_link.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> index b180197a41e2..84f0fd15be4c 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> @@ -744,6 +744,17 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
> break;
> case EDID_NO_RESPONSE:
> DC_LOG_ERROR("No EDID read.\n");
> +
> + /*
> + * Abort detection for non-DP connectors if we have
> + * no EDID
> + *
> + * DP needs to report as connected if HDP is high
> + * even if we have no EDID in order to go to
> + * fail-safe mode
> + */
> + if (!dc_is_dp_signal(link->connector_signal))
> + return false;
> default:
> break;
> }
> --
> 2.17.1
>
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