> Subject: [PATCH v2 09/34] drm/i915/dp_link_caps: Re-enable link
> configurations after sink caps change
> 
> Re-enable link configurations after sink capabilities change or the link got 
> reset
> before updating the link capabilities (due to an RX_CAP_CHANGED HPD IRQ for
> the currently connected sink, or a new sink getting connected).
> 
> This makes resetting the link explicitly by calling
> intel_dp_link_caps_reset() subsequently redundant; keep the existing behavior
> wrt. this for now, adding only a TODO: to remove the explicit reset.
> 
> While at it add documentation for intel_dp_link_caps_update().
> 
> Signed-off-by: Imre Deak <[email protected]>

LGTM,
Reviewed-by: Suraj Kandpal <[email protected]>

> ---
>  drivers/gpu/drm/i915/display/intel_dp.c       |  8 +++-
>  .../gpu/drm/i915/display/intel_dp_link_caps.c | 37 +++++++++++++++++--
> .../gpu/drm/i915/display/intel_dp_link_caps.h |  3 +-
>  3 files changed, 43 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 6e3fa6662cbef..23001541283b4 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -701,7 +701,8 @@ static bool intel_dp_set_common_link_params(struct
> intel_dp *intel_dp)
>       intel_dp_get_common_rates(intel_dp, common_rates,
> &num_common_rates);
>       if (intel_dp_link_caps_update(intel_dp->link.caps,
>                                     common_rates, num_common_rates,
> -
> intel_dp_get_max_common_lane_count(intel_dp)))
> +
> intel_dp_get_max_common_lane_count(intel_dp),
> +                                   intel_dp->reset_link_params))
>               params_changed = true;
> 
>       return params_changed;
> @@ -3652,6 +3653,11 @@ void intel_dp_set_link_params(struct intel_dp
> *intel_dp,
> 
>  void intel_dp_reset_link_params(struct intel_dp *intel_dp)  {
> +     /*
> +      * TODO: Remove the following reset of link capabilities, as
> +      * this isn't needed after intel_dp_link_caps_update(reset=true)
> +      * was called.
> +      */
>       intel_dp_link_caps_reset(intel_dp->link.caps);
>       intel_dp->link.mst_probed_lane_count = 0;
>       intel_dp->link.mst_probed_rate = 0;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> index 667d2e55cea19..de520bd423d59 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> @@ -709,14 +709,42 @@ static int link_config_cmp_by_lane_rate(const void
> *a, const void *b, const void
>       return lce_a->link_rate_idx - lce_b->link_rate_idx;  }
> 
> -/* Return %true if the supported link parameters have changed. */
> +/**
> + * intel_dp_link_caps_update - rebuild the supported link configuration
> +state
> + * @link_caps: link capabilities state
> + * @rates: supported common link rates
> + * @num_rates: number of entries in @rates
> + * @max_lane_count: supported maximum lane count
> + * @reset: reset limits and disabled configs
> + *
> + * Rebuild the supported link configuration state from @rates and
> + * @max_lane_count.
> + *
> + * If @reset is %true, reset the maximum link limits to the maximum
> + * supported rate and lane count, and re-enable all configurations.
> + *
> + * This function is called regularly, at least after a sink is
> +connected,
> + * but it may also be called later whenever the sink capabilities may
> +have
> + * changed, for example in response to HPD IRQ / RX_CAP_CHANGED
> signaling.
> + *
> + * In the Intel driver this function is currently called whenever the
> + * connector detect handler runs, after reading the sink capabilities.
> +This
> + * may change if those capabilities are cached until the sink is
> + * disconnected, or until RX_CAP_CHANGED is signaled. In any case, this
> + * function should be called whenever the sink capabilities were read
> +out
> + * and may have changed.
> + *
> + * Returns:
> + * - %true if the link capabilities have changed, %false otherwise.
> + */
>  bool intel_dp_link_caps_update(struct intel_dp_link_caps *link_caps,
> -                            const int *rates, int num_rates, int
> max_lane_count)
> +                            const int *rates, int num_rates, int
> max_lane_count,
> +                            bool reset)
>  {
>       struct intel_dp *intel_dp = link_caps->dp;
>       struct intel_display *display = to_intel_display(intel_dp);
>       struct intel_dp_link_config_entry *lce;
> -     bool link_params_changed = false;
> +     bool link_params_changed = reset;
>       int num_common_lane_configs;
>       int i;
>       int j;
> @@ -778,6 +806,9 @@ bool intel_dp_link_caps_update(struct
> intel_dp_link_caps *link_caps,
>              link_config_cmp_by_lane_rate, NULL,
>              link_caps);
> 
> +     if (link_params_changed)
> +             reset_max_link_limits_reenable_all(link_caps);
> +
>       return link_params_changed;
>  }
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_caps.h
> b/drivers/gpu/drm/i915/display/intel_dp_link_caps.h
> index 79aca74ad9eee..dcbde890809bc 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.h
> @@ -147,7 +147,8 @@ bool intel_dp_link_caps_set_max_limits(struct
> intel_dp_link_caps *link_caps,  void
> intel_dp_link_caps_reset_max_limits(struct intel_dp_link_caps *link_caps);
> 
>  bool intel_dp_link_caps_update(struct intel_dp_link_caps *link_caps,
> -                            const int *rates, int num_rates, int
> max_lane_count);
> +                            const int *rates, int num_rates, int
> max_lane_count,
> +                            bool reset);
>  void intel_dp_link_caps_reset(struct intel_dp_link_caps *link_caps);
> 
>  void intel_dp_link_caps_debugfs_add(struct intel_connector *connector);
> --
> 2.49.1

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