[PATCH v4] drm/i915/cx0: Set power state to ready only on owned PHY lanes

[Vamsi Krishna Brahmajosyula]

In DP alt mode, when pin assignment is D, only one PHY lane is owned
by the display. intel_cx0pll_enable currently performs a power state
ready on both the lanes in all cases.

Address the following todo to perfom power state ready on owned lanes.
    TODO: For DP alt mode use only one lane.

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

Signed-off-by: Vamsi Krishna Brahmajosyula <vamsikrishna.brahmajosyula at gmail.com>
---
v3 -> v4:
- Rebase code
- Include exact TODO to the commit message
v2 -> v3:
- Fix changelog per Jani Nikula's feedback
v1 -> v2: Address Gustavo Sousa's feedback
- Use owned lanes mask to set Phy power state to Ready, instead of
  maxpclk_lane with DP alt mode check.
- Owned lanes are obtained from intel_cx0_get_owned_lane_mask().
---
 drivers/gpu/drm/i915/display/intel_cx0_phy.c | 6 +++---
 1 file changed, 3 insertions(+), 3 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..cbed53d3b250 100644
--- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
+++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
@@ -2934,6 +2934,7 @@ static void intel_cx0pll_enable(struct intel_encoder *encoder,
 	enum phy phy = intel_encoder_to_phy(encoder);
 	struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
 	bool lane_reversal = dig_port->saved_port_bits & DDI_BUF_PORT_REVERSAL;
+	u8 owned_lane_mask = intel_cx0_get_owned_lane_mask(encoder);
 	u8 maxpclk_lane = lane_reversal ? INTEL_CX0_LANE1 :
 					  INTEL_CX0_LANE0;
 	intel_wakeref_t wakeref = intel_cx0_phy_transaction_begin(encoder);
@@ -2948,10 +2949,9 @@ static void intel_cx0pll_enable(struct intel_encoder *encoder,
 	intel_cx0_phy_lane_reset(encoder, lane_reversal);
 
 	/*
-	 * 3. Change Phy power state to Ready.
-	 * TODO: For DP alt mode use only one lane.
+	 * 3. Change Phy power state to Ready on owned lanes.
 	 */
-	intel_cx0_powerdown_change_sequence(encoder, INTEL_CX0_BOTH_LANES,
+	intel_cx0_powerdown_change_sequence(encoder, owned_lane_mask,
 					    CX0_P2_STATE_READY);
 
 	/*

base-commit: 2d5404caa8c7bb5c4e0435f94b28834ae5456623
-- 
2.47.0