drm/i915/dp: Use the generic helper to control LTTPR transparent mode

LTTPRs operating modes are defined by the DisplayPort standard and the
generic framework now provides a helper to switch between them, which
is handling the explicit disabling of non-transparent mode and its
disable->enable sequence mentioned in the DP Standard v2.0 section
3.6.6.1.

So use the new drm generic helper instead as it makes the code a bit
cleaner. Since the driver specific implementation holds the
lttrp_common_caps, if the call to the drm generic helper fails, the
lttrp_common_caps need to be updated as the helper has already rolled
back to transparent mode.

Acked-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250203-drm-dp-msm-add-lttpr-transparent-mode-set-v5-3-c865d0e56d6e@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index 05a8b6f6f349c2b19a5dd91f30dba9fbc88bd3c0..50e8daf8cd0b6f141d6238dacf46da87ae4f26d8 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -119,9 +119,6 @@ intel_dp_set_lttpr_transparent_mode(struct intel_dp *intel_dp, bool enable)
        u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
                          DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
 
-       if (drm_dp_dpcd_write(&intel_dp->aux, DP_PHY_REPEATER_MODE, &val, 1) != 1)
-               return false;
-
        intel_dp->lttpr_common_caps[DP_PHY_REPEATER_MODE -
                                    DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV] = val;
 
@@ -146,6 +143,7 @@ bool intel_dp_lttpr_transparent_mode_enabled(struct intel_dp *intel_dp)
 static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 {
        int lttpr_count;
+       int ret;
 
        if (!intel_dp_read_lttpr_common_caps(intel_dp, dpcd))
                return 0;
@@ -172,22 +170,8 @@ static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_
                return lttpr_count;
        }
 
-       /*
-        * See DP Standard v2.0 3.6.6.1. about the explicit disabling of
-        * non-transparent mode and the disable->enable non-transparent mode
-        * sequence.
-        */
-       intel_dp_set_lttpr_transparent_mode(intel_dp, true);
-
-       /*
-        * In case of unsupported number of LTTPRs or failing to switch to
-        * non-transparent mode fall-back to transparent link training mode,
-        * still taking into account any LTTPR common lane- rate/count limits.
-        */
-       if (lttpr_count < 0)
-               goto out_reset_lttpr_count;
-
-       if (!intel_dp_set_lttpr_transparent_mode(intel_dp, false)) {
+       ret = drm_dp_lttpr_init(&intel_dp->aux, lttpr_count);
+       if (ret) {
                lt_dbg(intel_dp, DP_PHY_DPRX,
                       "Switching to LTTPR non-transparent LT mode failed, fall-back to transparent mode\n");
 
@@ -196,6 +180,8 @@ static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_
                goto out_reset_lttpr_count;
        }
 
+       intel_dp_set_lttpr_transparent_mode(intel_dp, false);
+
        return lttpr_count;
 
 out_reset_lttpr_count: