On Fri, Jan 03, 2025 at 02:58:17PM +0200, Abel Vesa wrote:
> 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.
>
> Acked-by: Imre Deak <imre.d...@intel.com>
> Signed-off-by: Abel Vesa <abel.v...@linaro.org>
> ---
> .../gpu/drm/i915/display/intel_dp_link_training.c | 24
> +++++-----------------
> 1 file changed, 5 insertions(+), 19 deletions(-)
>
> 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
> 8b1977cfec503c70f07af716ee2c00e7605c6adf..c5bad311edf7b9a5cebb633b9e9692bae397f9ed
> 100644
> --- 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 @@ static 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);
> +
I think the code now misses a way to update intel_dp->lttpr_common_caps
in a transparent-mode case:
intel_dp_set_lttpr_transparent_mode(intel_dp, true).
> return lttpr_count;
>
> out_reset_lttpr_count:
>
> --
> 2.34.1
>
--
With best wishes
Dmitry
