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drm/i915/dp: Detect changes in common link parameters

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Detect DPRX capability changes without a long HPD or RX_CAP_CHANGED
signal and queue a corresponding link params reset.

Besides detecting the above unexpected capability changes, this also
avoids races between queuing and handling a deferred link params reset.

v2: (Ville)
- Query/set intel_dp::reset_link_params instead of using helpers for
  these.
- Assert matching types for old/new common rate elements as well.
- Add TODO: for adding a struct tracking both rates and number of rates.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260522160514.2628249-5-imre.deak@intel.com
This commit is contained in:
Imre Deak 2026-05-22 19:05:14 +03:00
parent cc18eac531
commit c0c49dead6
1 changed files with 47 additions and 7 deletions
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54
drivers/gpu/drm/i915/display/intel_dp.c
View File

@ -362,19 +362,25 @@ int intel_dp_max_source_lane_count(struct intel_digital_port *dig_port)
return max_lanes;
}
/* Theoretical max between source and sink */
static void intel_dp_set_max_common_lane_count(struct intel_dp *intel_dp)
/*
* Theoretical max between source and sink.
* Return %true if the max common lane count changed.
*/
static bool intel_dp_set_max_common_lane_count(struct intel_dp *intel_dp)
{
struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
int source_max = intel_dp_max_source_lane_count(dig_port);
int sink_max = intel_dp->max_sink_lane_count;
int lane_max = intel_tc_port_max_lane_count(dig_port);
int lttpr_max = drm_dp_lttpr_max_lane_count(intel_dp->lttpr_common_caps);
int old_max_common_lane_count = intel_dp->max_common_lane_count;
if (lttpr_max)
sink_max = min(sink_max, lttpr_max);
intel_dp->max_common_lane_count = min3(source_max, sink_max, lane_max);
return intel_dp->max_common_lane_count != old_max_common_lane_count;
}
int intel_dp_max_common_lane_count(struct intel_dp *intel_dp)
@ -792,13 +798,22 @@ int intel_dp_link_config_index(struct intel_dp *intel_dp, int link_rate, int lan
return -1;
}
static void intel_dp_set_common_rates(struct intel_dp *intel_dp)
/* Return %true if the common rates changed. */
static bool intel_dp_set_common_rates(struct intel_dp *intel_dp)
{
struct intel_display *display = to_intel_display(intel_dp);
int num_old_common_rates = intel_dp->num_common_rates;
int old_common_rates[DP_MAX_SUPPORTED_RATES];
drm_WARN_ON(display->drm,
!intel_dp->num_source_rates || !intel_dp->num_sink_rates);
/* TODO: Add a struct containing both rates and number of rates. */
static_assert(__same_type(old_common_rates[0], intel_dp->common_rates[0]) &&
sizeof(old_common_rates) == sizeof(intel_dp->common_rates));
memcpy(old_common_rates, intel_dp->common_rates,
num_old_common_rates * sizeof(old_common_rates[0]));
intel_dp->num_common_rates = intersect_rates(intel_dp->source_rates,
intel_dp->num_source_rates,
intel_dp->sink_rates,
@ -810,13 +825,26 @@ static void intel_dp_set_common_rates(struct intel_dp *intel_dp)
intel_dp->common_rates[0] = 162000;
intel_dp->num_common_rates = 1;
}
return num_old_common_rates != intel_dp->num_common_rates ||
memcmp(old_common_rates, intel_dp->common_rates,
num_old_common_rates * sizeof(old_common_rates[0]));
}
static void intel_dp_set_common_link_params(struct intel_dp *intel_dp)
/* Return %true if any common link param changed. */
static bool intel_dp_set_common_link_params(struct intel_dp *intel_dp)
{
intel_dp_set_common_rates(intel_dp);
intel_dp_set_max_common_lane_count(intel_dp);
bool params_changed = false;
if (intel_dp_set_common_rates(intel_dp))
params_changed = true;
if (intel_dp_set_max_common_lane_count(intel_dp))
params_changed = true;
intel_dp_link_config_init(intel_dp);
return params_changed;
}
bool intel_dp_link_params_valid(struct intel_dp *intel_dp, int link_rate,
@ -4885,9 +4913,21 @@ intel_dp_has_sink_count(struct intel_dp *intel_dp)
void intel_dp_update_sink_caps(struct intel_dp *intel_dp)
{
struct intel_display *display = to_intel_display(intel_dp);
intel_dp_set_sink_rates(intel_dp);
intel_dp_set_max_sink_lane_count(intel_dp);
intel_dp_set_common_link_params(intel_dp);
/*
* Handle unexpected sink cap changes, or a race between setting
* the deferred link params flag in the HPD IRQ handler and
* clearing the flag during connector detect.
*/
if (intel_dp_set_common_link_params(intel_dp) &&
!intel_dp->reset_link_params) {
drm_dbg_kms(display->drm,
"DPRX capabilities changed before long HPD or RX_CAP_CHANGED signal\n");
intel_dp->reset_link_params = true;
}
}
static bool