[PATCH] drm/i915/cx0: Use one lane to set power state to ready in DP alt mode

[Vamsi Krishna Brahmajosyula]

In DP alt mode one lane is owned by display and the other by usb
intel_cx0pll_enable currently performs a power cycle ready on both
the lanes in all cases.

Address the todo to perfom power state ready only on the display lane
when DP alt mode is enabled.

Tested on Meteor Lake-P [Intel Arc Graphics] with DP alt mode.

Signed-off-by: Vamsi Krishna Brahmajosyula <vamsikrishna.brahmajosyula at gmail.com>
---
 drivers/gpu/drm/i915/display/intel_cx0_phy.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
index 4a6c3040ca15..47aa0418379c 100644
--- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
+++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
@@ -2949,9 +2949,13 @@ static void intel_cx0pll_enable(struct intel_encoder *encoder,
 
 	/*
 	 * 3. Change Phy power state to Ready.
-	 * TODO: For DP alt mode use only one lane.
+	 * For DP alt mode use only one lane.
 	 */
-	intel_cx0_powerdown_change_sequence(encoder, INTEL_CX0_BOTH_LANES,
+	if (intel_tc_port_in_dp_alt_mode(dig_port))
+		intel_cx0_powerdown_change_sequence(encoder, maxpclk_lane,
+					    CX0_P2_STATE_READY);
+	else
+		intel_cx0_powerdown_change_sequence(encoder, INTEL_CX0_BOTH_LANES,
 					    CX0_P2_STATE_READY);
 
 	/*

base-commit: b831f83e40a24f07c8dcba5be408d93beedc820f
-- 
2.46.0