Re: [Intel-gfx] [PATCH 3/3] drm/i915/dp: use new link training delay helpers

Jani Nikula
2021-10-19T15:38:17Z

On Thu, 14 Oct 2021, Jani Nikula <jani.nikula@intel.com> wrote:
> Use the new link training delay helpers, fixing the delays for
> 128b/132b.
>
> For existing 8b/10b functionality, this will cause additional 1-byte
> DPCD reads for LTTPR delays instead of using the cached values. It's
> just too complicated to combine generic helpers with local caching in a
> sensible way.
>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Thanks for the review.

Pushed & got patches 1-2 merged via a topic branch to both drm-misc-next
and drm-intel-next, and pushed patch 3 on top to drm-intel-next.

BR,
Jani.

> ---
> .../drm/i915/display/intel_dp_link_training.c | 38 +++++++------------
> 1 file changed, 13 insertions(+), 25 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 85676c953e0a..a72f2dc93718 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -683,15 +683,6 @@ intel_dp_prepare_link_train(struct intel_dp *intel_dp,
> return true;
> }
>
> -static void intel_dp_link_training_clock_recovery_delay(struct intel_dp *intel_dp,
> - enum drm_dp_phy dp_phy)
> -{
> - if (dp_phy == DP_PHY_DPRX)
> - drm_dp_link_train_clock_recovery_delay(&intel_dp->aux, intel_dp->dpcd);
> - else
> - drm_dp_lttpr_link_train_clock_recovery_delay();
> -}
> -
> static bool intel_dp_adjust_request_changed(const struct intel_crtc_state *crtc_state,
> const u8 old_link_status[DP_LINK_STATUS_SIZE],
> const u8 new_link_status[DP_LINK_STATUS_SIZE])
> @@ -750,6 +741,11 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp,
> u8 link_status[DP_LINK_STATUS_SIZE];
> bool max_vswing_reached = false;
> char phy_name[10];
> + int delay_us;
> +
> + delay_us = drm_dp_read_clock_recovery_delay(&intel_dp->aux,
> + intel_dp->dpcd, dp_phy,
> + intel_dp_is_uhbr(crtc_state));
>
> intel_dp_phy_name(dp_phy, phy_name, sizeof(phy_name));
>
> @@ -777,7 +773,7 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp,
>
> voltage_tries = 1;
> for (cr_tries = 0; cr_tries < max_cr_tries; ++cr_tries) {
> - intel_dp_link_training_clock_recovery_delay(intel_dp, dp_phy);
> + usleep_range(delay_us, 2 * delay_us);
>
> if (drm_dp_dpcd_read_phy_link_status(&intel_dp->aux, dp_phy,
> link_status) < 0) {
> @@ -895,19 +891,6 @@ static u32 intel_dp_training_pattern(struct intel_dp *intel_dp,
> return DP_TRAINING_PATTERN_2;
> }
>
> -static void
> -intel_dp_link_training_channel_equalization_delay(struct intel_dp *intel_dp,
> - enum drm_dp_phy dp_phy)
> -{
> - if (dp_phy == DP_PHY_DPRX) {
> - drm_dp_link_train_channel_eq_delay(&intel_dp->aux, intel_dp->dpcd);
> - } else {
> - const u8 *phy_caps = intel_dp_lttpr_phy_caps(intel_dp, dp_phy);
> -
> - drm_dp_lttpr_link_train_channel_eq_delay(&intel_dp->aux, phy_caps);
> - }
> -}
> -
> /*
> * Perform the link training channel equalization phase on the given DP PHY
> * using one of training pattern 2, 3 or 4 depending on the source and
> @@ -925,6 +908,11 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp,
> u8 link_status[DP_LINK_STATUS_SIZE];
> bool channel_eq = false;
> char phy_name[10];
> + int delay_us;
> +
> + delay_us = drm_dp_read_channel_eq_delay(&intel_dp->aux,
> + intel_dp->dpcd, dp_phy,
> + intel_dp_is_uhbr(crtc_state));
>
> intel_dp_phy_name(dp_phy, phy_name, sizeof(phy_name));
>
> @@ -944,8 +932,8 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp,
> }
>
> for (tries = 0; tries < 5; tries++) {
> - intel_dp_link_training_channel_equalization_delay(intel_dp,
> - dp_phy);
> + usleep_range(delay_us, 2 * delay_us);
> +
> if (drm_dp_dpcd_read_phy_link_status(&intel_dp->aux, dp_phy,
> link_status) < 0) {
> drm_err(&i915->drm,

--
Jani Nikula, Intel Open Source Graphics Center