Re: [PATCH 24/25] drm/i915/ltphy: Modify the step that need to by skipped

[Murthy, Arun R]

On 15-10-2025 09:38, Suraj Kandpal wrote:

Bspec has changed the non tbt pll enable sequence now we skip
steps 5-17 if no config change has occurred.

Signed-off-by: Suraj Kandpal <suraj.kand...@intel.com>
---

Reviewed-by: Arun R Murthy <arun.r.mur...@intel.com>

Thanks and Regards,
Arun R Murthy
--------------------

  drivers/gpu/drm/i915/display/intel_lt_phy.c | 63 +++++++++++----------
  1 file changed, 33 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_lt_phy.c 
b/drivers/gpu/drm/i915/display/intel_lt_phy.c
index 72c3ba787e2a..0262c3a97020 100644
--- a/drivers/gpu/drm/i915/display/intel_lt_phy.c
+++ b/drivers/gpu/drm/i915/display/intel_lt_phy.c
@@ -1664,40 +1664,43 @@ void intel_lt_phy_pll_enable(struct intel_encoder 
*encoder,
                                         XE3PLPD_MACCLK_TURNON_LATENCY_US, 2, 
NULL))
                        drm_warn(display->drm, "PHY %c PLL MacCLK Ack assertion 
Timeout after %dus.\n",
                                 phy_name(phy), 
XE3PLPD_MACCLK_TURNON_LATENCY_US);
+
+               /*
+                * 13. Ungate the forward clock by setting
+                * PORT_CLOCK_CTL[Forward Clock Ungate] = 1.
+                */
+               intel_de_rmw(display, XELPDP_PORT_CLOCK_CTL(display, port),
+                            XELPDP_FORWARD_CLOCK_UNGATE,
+                            XELPDP_FORWARD_CLOCK_UNGATE);
+
+               /* 14. SW clears PORT_BUF_CTL2 [PHY Pulse Status]. */
+               intel_de_rmw(display, XELPDP_PORT_BUF_CTL2(display, port),
+                            lane_phy_pulse_status,
+                            lane_phy_pulse_status);
+               /*
+                * 15. Clear the PHY VDR register 0xCC4[Rate Control VDR 
Update] over
+                * PHY message bus for Owned PHY Lanes.
+                */
+               rate_update = intel_lt_phy_read(encoder, INTEL_LT_PHY_LANE0, 
LT_PHY_RATE_UPDATE);
+               rate_update &= ~LT_PHY_RATE_CONTROL_VDR_UPDATE;
+               intel_lt_phy_write(encoder, owned_lane_mask, LT_PHY_RATE_UPDATE,
+                                  rate_update, MB_WRITE_COMMITTED);
+
+               /* 16. Poll for PORT_BUF_CTL2 register PHY Pulse Status = 1 for 
Owned PHY Lanes. */
+               if (intel_de_wait_custom(display, XELPDP_PORT_BUF_CTL2(display, 
port),
+                                        lane_phy_pulse_status, 
lane_phy_pulse_status,
+                                        XE3PLPD_RATE_CALIB_DONE_LATENCY_US, 2, 
NULL))
+                       drm_warn(display->drm, "PHY %c PLL rate not changed after 
%dus.\n",
+                                phy_name(phy), 
XE3PLPD_RATE_CALIB_DONE_LATENCY_US);
+
+               /* 17. SW clears PORT_BUF_CTL2 [PHY Pulse Status]. */
+               intel_de_rmw(display, XELPDP_PORT_BUF_CTL2(display, port),
+                            lane_phy_pulse_status,
+                            lane_phy_pulse_status);
        } else {
                intel_de_write(display, DDI_CLK_VALFREQ(encoder->port), 
crtc_state->port_clock);
        }

- /* 13. Ungate the forward clock by setting PORT_CLOCK_CTL[Forward Clock Ungate] = 1. */

-       intel_de_rmw(display, XELPDP_PORT_CLOCK_CTL(display, port),
-                    XELPDP_FORWARD_CLOCK_UNGATE,
-                    XELPDP_FORWARD_CLOCK_UNGATE);
-
-       /* 14. SW clears PORT_BUF_CTL2 [PHY Pulse Status]. */
-       intel_de_rmw(display, XELPDP_PORT_BUF_CTL2(display, port),
-                    lane_phy_pulse_status,
-                    lane_phy_pulse_status);
-       /*
-        * 15. Clear the PHY VDR register 0xCC4[Rate Control VDR Update] over 
PHY message bus for
-        * Owned PHY Lanes.
-        */
-       rate_update = intel_lt_phy_read(encoder, INTEL_LT_PHY_LANE0, 
LT_PHY_RATE_UPDATE);
-       rate_update &= ~LT_PHY_RATE_CONTROL_VDR_UPDATE;
-       intel_lt_phy_write(encoder, owned_lane_mask, LT_PHY_RATE_UPDATE,
-                          rate_update, MB_WRITE_COMMITTED);
-
-       /* 16. Poll for PORT_BUF_CTL2 register PHY Pulse Status = 1 for Owned 
PHY Lanes. */
-       if (intel_de_wait_custom(display, XELPDP_PORT_BUF_CTL2(display, port),
-                                lane_phy_pulse_status, lane_phy_pulse_status,
-                                XE3PLPD_RATE_CALIB_DONE_LATENCY_US, 2, NULL))
-               drm_warn(display->drm, "PHY %c PLL rate not changed after 
%dus.\n",
-                        phy_name(phy), XE3PLPD_RATE_CALIB_DONE_LATENCY_US);
-
-       /* 17. SW clears PORT_BUF_CTL2 [PHY Pulse Status]. */
-       intel_de_rmw(display, XELPDP_PORT_BUF_CTL2(display, port),
-                    lane_phy_pulse_status,
-                    lane_phy_pulse_status);
-
        /*
         * 18. Follow the Display Voltage Frequency Switching - Sequence After 
Frequency Change.
         * We handle this step in bxt_set_cdclk()