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drm/i915/dp_link_caps: Add support for link rate, lane count iteration orders

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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.

Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260701153204.4124150-4-imre.deak@intel.com
This commit is contained in:
Imre Deak 2026-07-01 18:31:32 +03:00
parent 87b7964494
commit 4074974b71
1 changed files with 50 additions and 0 deletions
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50
drivers/gpu/drm/i915/display/intel_dp_link_caps.c
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@ -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;
}