> Subject: [PATCH v2 03/34] drm/i915/dp_link_caps: Add support for link rate,
> lane count iteration orders
> 
> Add support for iterating configurations in either link rate/lane count or 
> lane
> count/link rate order. Both orders are required for DP SST connector types: 
> the
> former for computing the connector state during a modeset, and the latter for
> selecting a fallback configuration after a link training failure.
> 
> Signed-off-by: Imre Deak <[email protected]>

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

> ---
>  .../gpu/drm/i915/display/intel_dp_link_caps.c | 50 +++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> 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 d0a863b00b458..fe5a11efbe67b 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> @@ -122,6 +122,13 @@ struct intel_dp_link_caps {
>               u8 lane_count_exp:INTEL_DP_LANE_COUNT_EXP_BITS;
>       } configs[INTEL_DP_MAX_LINK_CONFIGS];
> 
> +     /*
> +      * Indices to intel_dp_link_caps::configs[] in rate/lane count,
> +      * lane_count/rate order.
> +      */
> +     u8 rate_lane_map[INTEL_DP_MAX_LINK_CONFIGS];
> +     u8 lane_rate_map[INTEL_DP_MAX_LINK_CONFIGS];
> +
>       /*
>        * Forced parameters requested via debugfs. Remains set across sink
>        * disconnects.
> @@ -350,6 +357,34 @@ static int link_config_cmp_by_bw(const void *a, const
> void *b, const void *p)
>              intel_dp_link_config_rate(link_caps, lce_b);  }
> 
> +static int link_config_cmp_by_rate_lane(const void *a, const void *b,
> +const void *p) {
> +     const struct intel_dp_link_caps *link_caps = p;
> +     u8 *lce_a_idx = (u8 *)a;
> +     u8 *lce_b_idx = (u8 *)b;
> +     const struct intel_dp_link_config_entry *lce_a = &link_caps-
> >configs[*lce_a_idx];
> +     const struct intel_dp_link_config_entry *lce_b =
> +&link_caps->configs[*lce_b_idx];
> +
> +     if (lce_a->link_rate_idx != lce_b->link_rate_idx)
> +             return lce_a->link_rate_idx - lce_b->link_rate_idx;
> +
> +     return lce_a->lane_count_exp - lce_b->lane_count_exp; }
> +
> +static int link_config_cmp_by_lane_rate(const void *a, const void *b,
> +const void *p) {
> +     const struct intel_dp_link_caps *link_caps = p;
> +     u8 *lce_a_idx = (u8 *)a;
> +     u8 *lce_b_idx = (u8 *)b;
> +     const struct intel_dp_link_config_entry *lce_a = &link_caps-
> >configs[*lce_a_idx];
> +     const struct intel_dp_link_config_entry *lce_b =
> +&link_caps->configs[*lce_b_idx];
> +
> +     if (lce_a->lane_count_exp != lce_b->lane_count_exp)
> +             return lce_a->lane_count_exp - lce_b->lane_count_exp;
> +
> +     return lce_a->link_rate_idx - lce_b->link_rate_idx; }
> +
>  /* Return %true if the supported link parameters have changed. */  bool
> intel_dp_link_caps_update(struct intel_dp_link_caps *link_caps,
>                              const int *rates, int num_rates, int
> max_lane_count) @@ -404,6 +439,21 @@ bool
> intel_dp_link_caps_update(struct intel_dp_link_caps *link_caps,
>              link_config_cmp_by_bw, NULL,
>              intel_dp);
> 
> +     for (i = 0; i < link_caps->num_configs; i++) {
> +             link_caps->rate_lane_map[i] = i;
> +             link_caps->lane_rate_map[i] = i;
> +     }
> +
> +     sort_r(link_caps->rate_lane_map, link_caps->num_configs,
> +            sizeof(link_caps->rate_lane_map[0]),
> +            link_config_cmp_by_rate_lane, NULL,
> +            link_caps);
> +
> +     sort_r(link_caps->lane_rate_map, link_caps->num_configs,
> +            sizeof(link_caps->lane_rate_map[0]),
> +            link_config_cmp_by_lane_rate, NULL,
> +            link_caps);
> +
>       return link_params_changed;
>  }
> 
> --
> 2.49.1

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