From 857c416e58dc306b15b7919117b6225544662bfa Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Fri, 27 Oct 2017 12:45:23 +0300 Subject: [PATCH] drm/i915: Improve DP downstream HPD handling MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit DP dongles may signal downstream HPD via short HPD pulses. Setting the sink to DPMS off apparently kills the downstream HPD (at least on my DP->VGA dongle), so skip the DPMS off for such dongles when we turn off the port. v2: Deal with DDI as well by moving the check into intel_dp_sink_dpms() (Dhinakaran) Cc: Dhinakaran Pandiyan Cc: David Woodhouse Cc: Imre Deak Cc: Pablo Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103472 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99114 Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20171027094523.9317-1-ville.syrjala@linux.intel.com Reviewed-by: Jani Nikula --- drivers/gpu/drm/i915/intel_dp.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 73b1ed8cff6b..8d25a019b772 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -2505,6 +2505,21 @@ static void ironlake_edp_pll_off(struct intel_dp *intel_dp) udelay(200); } +static bool downstream_hpd_needs_d0(struct intel_dp *intel_dp) +{ + /* + * DPCD 1.2+ should support BRANCH_DEVICE_CTRL, and thus + * be capable of signalling downstream hpd with a long pulse. + * Whether or not that means D3 is safe to use is not clear, + * but let's assume so until proven otherwise. + * + * FIXME should really check all downstream ports... + */ + return intel_dp->dpcd[DP_DPCD_REV] == 0x11 && + intel_dp->dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT && + intel_dp->downstream_ports[0] & DP_DS_PORT_HPD; +} + /* If the sink supports it, try to set the power state appropriately */ void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode) { @@ -2515,6 +2530,9 @@ void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode) return; if (mode != DRM_MODE_DPMS_ON) { + if (downstream_hpd_needs_d0(intel_dp)) + return; + ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, DP_SET_POWER_D3); } else { -- 2.11.0