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* [RESEND] drm/i915/aux: use polling when irqs are unavailable
@ 2026-04-16 16:37 Michał Grzelak
  2026-04-16 17:25 ` ✓ i915.CI.BAT: success for drm/i915/aux: use polling when irqs are unavailable (rev3) Patchwork
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: Michał Grzelak @ 2026-04-16 16:37 UTC (permalink / raw)
  To: intel-gfx, intel-xe; +Cc: Michał Grzelak, Ville Syrjälä

PTL with physically disconnected display was observed to have 40s longer
execution time when testing xe_fault_injection@xe_guc_mmio_send_recv.
The issue has not been seen when reverting commit 40a9f77a28fa ("Revert
"drm/i915/dp: change aux_ctl reg read to polling read"").

Apparently the configuration suffers from not having AUX enabled when
using interrupts. One probable cause can be xe enabling interrupts too
late: interrupts need memory allocations which currently can't be done
before the display FB takeover is done.

As for now, use polling for AUX in case interrupts are unavailable.

Fixes: 40a9f77a28fa ("Revert "drm/i915/dp: change aux_ctl reg read to polling read"")
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Michał Grzelak <michal.grzelak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_aux.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
index b20ec3e589fad..9c9b6410366d5 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
@@ -12,6 +12,7 @@
 #include "intel_dp.h"
 #include "intel_dp_aux.h"
 #include "intel_dp_aux_regs.h"
+#include "intel_parent.h"
 #include "intel_pps.h"
 #include "intel_quirks.h"
 #include "intel_tc.h"
@@ -60,18 +61,29 @@ intel_dp_aux_wait_done(struct intel_dp *intel_dp)
 	struct intel_display *display = to_intel_display(intel_dp);
 	i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
 	const unsigned int timeout_ms = 10;
+	bool done = true;
 	u32 status;
-	bool done;
+	int ret;
 
+	if (intel_parent_irq_enabled(display)) {
 #define C (((status = intel_de_read_notrace(display, ch_ctl)) & DP_AUX_CH_CTL_SEND_BUSY) == 0)
-	done = wait_event_timeout(display->gmbus.wait_queue, C,
-				  msecs_to_jiffies_timeout(timeout_ms));
+		done = wait_event_timeout(display->gmbus.wait_queue, C,
+					  msecs_to_jiffies_timeout(timeout_ms));
+
+#undef C
+	} else {
+		ret = intel_de_wait_ms(display, ch_ctl,
+				       DP_AUX_CH_CTL_SEND_BUSY, 0,
+				       timeout_ms, &status);
+
+		if (ret == -ETIMEDOUT)
+			done = false;
+	}
 
 	if (!done)
 		drm_err(display->drm,
 			"%s: did not complete or timeout within %ums (status 0x%08x)\n",
 			intel_dp->aux.name, timeout_ms, status);
-#undef C
 
 	return status;
 }
-- 
2.45.2


^ permalink raw reply related	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-05-19 13:20 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2026-04-16 16:37 [RESEND] drm/i915/aux: use polling when irqs are unavailable Michał Grzelak
2026-04-16 17:25 ` ✓ i915.CI.BAT: success for drm/i915/aux: use polling when irqs are unavailable (rev3) Patchwork
2026-04-20 13:29 ` ✓ i915.CI.Full: " Patchwork
2026-05-19 13:20 ` [RESEND] drm/i915/aux: use polling when irqs are unavailable Ville Syrjälä

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