[SRU][R][PATCH 19/22] drm/i915/dp: Check SST link status while handling link service IRQs

[Werner Sembach]

From: Imre Deak <imre.deak at intel.com>

Move checking the link status for SST to
intel_dp_handle_link_service_irq(). This is the logical place for the
check which should only happen in response to a LINK_STATUS_CHANGE sink
IRQ. This IRQ is only supported by DPCD revision >= 1.2, so for sinks
with an older DPCD revision the link status is checked in response to
any HPD IRQ. For newer DPCD revisions however the link status check can
be made conditional on LINK_STATUS_CHANGE.

For now keep the current behavior of always forcing a link status check
regardless of LINK_STATUS_CHANGE being set or not.

This also prepares for a follow-up change sharing the link service IRQ
handler for SST and MST (on MST the link status check only happening in
response to a LINK_STATUS_CHANGE IRQ).

Reviewed-by: Luca Coelho <luciano.coelho at intel.com>
Signed-off-by: Imre Deak <imre.deak at intel.com>
Link: https://patch.msgid.link/20260225164618.1261368-18-imre.deak@intel.com
Signed-off-by: Werner Sembach <wse at tuxedocomputers.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 7888abb5c9feb..e811f3bbc7220 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5763,6 +5763,9 @@ static bool intel_dp_handle_link_service_irq(struct intel_dp *intel_dp, u8 irq_m
 	if (irq_mask & RX_CAP_CHANGED)
 		reprobe_needed = true;
 
+	if (irq_mask & LINK_STATUS_CHANGED)
+		intel_dp_check_link_state(intel_dp);
+
 	if (irq_mask & HDMI_LINK_STATUS_CHANGED)
 		intel_dp_handle_hdmi_link_status_change(intel_dp);
 
@@ -5816,14 +5819,18 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
 
 	intel_dp_handle_device_service_irq(intel_dp, esi[1]);
 
+	/*
+	 * Force checking the link status for DPCD_REV < 1.2
+	 * TODO: let the link status check depend on LINK_STATUS_CHANGED
+	 * for DPCD_REV >= 1.2
+	 */
+	esi[3] |= LINK_STATUS_CHANGED;
 	if (intel_dp_handle_link_service_irq(intel_dp, esi[3]))
 		reprobe_needed = true;
 
 	/* Handle CEC interrupts, if any */
 	drm_dp_cec_irq(&intel_dp->aux);
 
-	intel_dp_check_link_state(intel_dp);
-
 	if (READ_ONCE(intel_dp->downstream_port_changed)) {
 		WRITE_ONCE(intel_dp->downstream_port_changed, false);
 		reprobe_needed = true;
-- 
2.43.0