From d68a3caf96bcf24debdc2276b59b82774c71ced7 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 4 Nov 2019 13:53:07 +0000
Subject: drm/i915/execlists: Reset CSB pointers by mmio as well
Git-commit: 0a1f57b86c0b1bdc522ed5c96afdb67931e1d495
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
Sometimes Icelake forgets to reset the CSB pointers on a GPU reset,
leading to it carry on updating the old tail of the buffer.
<0>[ 618.138490] i915_sel-5636 3d..1 673425465us : trace_ports: vecs0: submit { 14de2:504, 0:0 }
<0>[ 618.138490] i915_sel-5636 3.... 673425493us : intel_engine_reset: vecs0 flags=100
<0>[ 618.138490] i915_sel-5636 3.... 673425493us : execlists_reset_prepare: vecs0: depth<-0
<0>[ 618.138490] i915_sel-5636 3.... 673425493us : intel_engine_stop_cs: vecs0
<0>[ 618.138490] i915_sel-5636 3.... 673425523us : __intel_gt_reset: engine_mask=40
<0>[ 618.138490] i915_sel-5636 3.... 673425568us : execlists_reset: vecs0
<0>[ 618.138490] i915_sel-5636 3d..1 673425568us : process_csb: vecs0 cs-irq head=1, tail=2
<0>[ 618.138490] i915_sel-5636 3d..1 673425568us : process_csb: vecs0 csb[2]: status=0x00000001:0x40000000
<0>[ 618.138490] i915_sel-5636 3d..1 673425569us : trace_ports: vecs0: promote { 14de2:504*, 0:0 }
<0>[ 618.138490] i915_sel-5636 3d..1 673425570us : __i915_request_reset: vecs0 rq=14de2:504, guilty? yes
<0>[ 618.138490] i915_sel-5636 3d..1 673425571us : __execlists_reset: vecs0 replay {head:2de0, tail:2e48}
<0>[ 618.138490] i915_sel-5636 3d..1 673425572us : __i915_request_unsubmit: vecs0 fence 14de2:504, current 503
<0>[ 618.138490] i915_sel-5636 3.... 673435544us : intel_engine_cancel_stop_cs: vecs0
<0>[ 618.138490] i915_sel-5636 3.... 673435544us : process_csb: vecs0 cs-irq head=11, tail=11
<0>[ 618.138490] i915_sel-5636 3d..1 673435545us : __i915_request_submit: vecs0 fence 14de2:504, current 503
<0>[ 618.138490] i915_sel-5636 3d..1 673435546us : __execlists_submission_tasklet: vecs0: queue_priority_hint:-2147483648, submit:yes
<0>[ 618.138490] i915_sel-5636 3d..1 673435548us : trace_ports: vecs0: submit { 14de2:504*, 0:0 }
<0>[ 618.138490] i915_sel-5636 3.... 673435549us : execlists_reset_finish: vecs0: depth->0
<0>[ 618.138490] ksoftirq-21 2..s. 673435592us : process_csb: vecs0 cs-irq head=11, tail=3
<0>[ 618.138490] ksoftirq-21 2..s. 673435593us : process_csb: vecs0 csb[0]: status=0x00000001:0x40000000
<0>[ 618.138490] ksoftirq-21 2..s. 673435594us : trace_ports: vecs0: promote { 14de2:504*, 0:0 }
<0>[ 618.138490] ksoftirq-21 2..s. 673435596us : process_csb: vecs0 csb[1]: status=0x00000018:0x40000040
<0>[ 618.138490] ksoftirq-21 2..s. 673435597us : trace_ports: vecs0: completed { 14de2:504*, 0:0 }
<0>[ 618.138490] ksoftirq-21 2..s. 673435612us : process_csb: process_csb:2188 GEM_BUG_ON(!i915_request_completed(*execlists->active) && !reset_in_progress(execlists))
After the reset, we do another clflush before checking the CSB to be
sure we see whatever was left in the CSB prior to the reset. So it is
unlikely to be an incoherent view of the CSB, and more likely that
Icelake didn't reset its pointers.
References: 582a6f90aa0d ("drm/i915/execlists: Add a paranoid flush of the CSB pointers upon reset")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191104135307.21083-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 3e0197c06ef1..935655b274f7 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -3020,6 +3020,14 @@ static void reset_csb_pointers(struct intel_engine_cs *engine)
WRITE_ONCE(*execlists->csb_write, reset_value);
wmb(); /* Make sure this is visible to HW (paranoia?) */
+ /*
+ * Sometimes Icelake forgets to reset its pointers on a GPU reset.
+ * Bludgeon them with a mmio update to be sure.
+ */
+ ENGINE_WRITE(engine, RING_CONTEXT_STATUS_PTR,
+ reset_value << 8 | reset_value);
+ ENGINE_POSTING_READ(engine, RING_CONTEXT_STATUS_PTR);
+
invalidate_csb_entries(&execlists->csb_status[0],
&execlists->csb_status[reset_value]);
}
--
2.28.0