[PATCH 3/3] drm/bridge: analogix_dp: don't adjust further when clock recovery succeeded

[Robert Foss]

On Mon, Mar 18, 2024 at 9:39 PM Lucas Stach <l.stach at pengutronix.de> wrote:
>
> Take a early return from the clock recovery training when the sink reports
> CR_DONE for all lanes. There is no point in trying to adjust the link
> parameters further.
>
> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> ---
>  .../drm/bridge/analogix/analogix_dp_core.c    | 58 +++++++++----------
>  1 file changed, 29 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 300385db7502..98454f0af90e 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -410,11 +410,6 @@ static int analogix_dp_process_clock_recovery(struct analogix_dp_device *dp)
>         if (retval < 0)
>                 return retval;
>
> -       retval = drm_dp_dpcd_read(&dp->aux, DP_ADJUST_REQUEST_LANE0_1,
> -                                 adjust_request, 2);
> -       if (retval < 0)
> -               return retval;
> -
>         if (analogix_dp_clock_recovery_ok(link_status, lane_count) == 0) {
>                 /* set training pattern 2 for EQ */
>                 analogix_dp_set_training_pattern(dp, TRAINING_PTN2);
> @@ -427,30 +422,35 @@ static int analogix_dp_process_clock_recovery(struct analogix_dp_device *dp)
>
>                 dev_dbg(dp->dev, "Link Training Clock Recovery success\n");
>                 dp->link_train.lt_state = EQUALIZER_TRAINING;
> -       } else {
> -               for (lane = 0; lane < lane_count; lane++) {
> -                       training_lane = analogix_dp_get_lane_link_training(
> -                                                       dp, lane);
> -                       voltage_swing = analogix_dp_get_adjust_request_voltage(
> -                                                       adjust_request, lane);
> -                       pre_emphasis = analogix_dp_get_adjust_request_pre_emphasis(
> -                                                       adjust_request, lane);
> -
> -                       if (DPCD_VOLTAGE_SWING_GET(training_lane) ==
> -                                       voltage_swing &&
> -                           DPCD_PRE_EMPHASIS_GET(training_lane) ==
> -                                       pre_emphasis)
> -                               dp->link_train.cr_loop[lane]++;
> -
> -                       if (dp->link_train.cr_loop[lane] == MAX_CR_LOOP ||
> -                           voltage_swing == VOLTAGE_LEVEL_3 ||
> -                           pre_emphasis == PRE_EMPHASIS_LEVEL_3) {
> -                               dev_err(dp->dev, "CR Max reached (%d,%d,%d)\n",
> -                                       dp->link_train.cr_loop[lane],
> -                                       voltage_swing, pre_emphasis);
> -                               analogix_dp_reduce_link_rate(dp);
> -                               return -EIO;
> -                       }
> +
> +               return 0;
> +       }
> +
> +       retval = drm_dp_dpcd_read(&dp->aux, DP_ADJUST_REQUEST_LANE0_1,
> +                                 adjust_request, 2);
> +       if (retval < 0)
> +               return retval;
> +
> +       for (lane = 0; lane < lane_count; lane++) {
> +               training_lane = analogix_dp_get_lane_link_training(
> +                                               dp, lane);
> +               voltage_swing = analogix_dp_get_adjust_request_voltage(
> +                                               adjust_request, lane);
> +               pre_emphasis = analogix_dp_get_adjust_request_pre_emphasis(
> +                                               adjust_request, lane);
> +

checkpatch --strict is throwing some warnings. Could these be fixed?

-:67: CHECK:OPEN_ENDED_LINE: Lines should not end with a '('
#67: FILE: drivers/gpu/drm/bridge/analogix/analogix_dp_core.c:435:
+        training_lane = analogix_dp_get_lane_link_training(

-:69: CHECK:OPEN_ENDED_LINE: Lines should not end with a '('
#69: FILE: drivers/gpu/drm/bridge/analogix/analogix_dp_core.c:437:
+        voltage_swing = analogix_dp_get_adjust_request_voltage(

-:71: CHECK:OPEN_ENDED_LINE: Lines should not end with a '('
#71: FILE: drivers/gpu/drm/bridge/analogix/analogix_dp_core.c:439:
+        pre_emphasis = analogix_dp_get_adjust_request_pre_emphasis(


> +               if (DPCD_VOLTAGE_SWING_GET(training_lane) == voltage_swing &&
> +                   DPCD_PRE_EMPHASIS_GET(training_lane) == pre_emphasis)
> +                       dp->link_train.cr_loop[lane]++;
> +
> +               if (dp->link_train.cr_loop[lane] == MAX_CR_LOOP ||
> +                   voltage_swing == VOLTAGE_LEVEL_3 ||
> +                   pre_emphasis == PRE_EMPHASIS_LEVEL_3) {
> +                       dev_err(dp->dev, "CR Max reached (%d,%d,%d)\n",
> +                               dp->link_train.cr_loop[lane],
> +                               voltage_swing, pre_emphasis);
> +                       analogix_dp_reduce_link_rate(dp);
> +                       return -EIO;
>                 }
>         }
>
> --
> 2.39.2
>

With the above corrected or checked, feel free to add my r-b.

Reviewed-by: Robert Foss <rfoss at kernel.org>