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drm/i915: Improve DP downstream HPD handling

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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 <dhinakaran.pandiyan@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Pablo <pablodebiase@nanalysis.com>
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 <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171027094523.9317-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Ville Syrjälä 2017-10-27 12:45:23 +03:00
parent 5161d058df
commit 857c416e58
1 changed files with 18 additions and 0 deletions
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18
drivers/gpu/drm/i915/intel_dp.c
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@ -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 {