From 0a1f57b86c0b1bdc522ed5c96afdb67931e1d495 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 4 Nov 2019 13:53:07 +0000 Subject: [PATCH] drm/i915/execlists: Reset CSB pointers by mmio as well 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 Cc: Mika Kuoppala Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20191104135307.21083-1-chris@chris-wilson.co.uk --- 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 8d79a965f341..1975fe4775d2 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -2996,6 +2996,14 @@ 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]); }