Hi, Should not be cherry picked to stable, it needs many more patches to make it work or otherwise breaks the platform. Regards, Tvrtko > -----Original Message----- > From: Kamal Mostafa [mailto:kamal@xxxxxxxxxxxxx] > Sent: Thursday, June 09, 2016 10:14 PM > To: linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; kernel- > team@xxxxxxxxxxxxxxxx > Cc: Chris Wilson; Ville Syrjälä; Antti Koskipää; Ursulin, Tvrtko; Kamal Mostafa > Subject: [PATCH 4.2.y-ckt 006/206] drm/i915: Exit cherryview_irq_handler() > after one pass > > 4.2.8-ckt12 -stable review patch. If anyone has any objections, please let me > know. > > ---8<------------------------------------------------------------ > > From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > commit 579de73b048a0a4c66c25a033ac76a2836e0cf73 upstream. > > This effectively reverts > > commit 8e5fd599eb219f1054e39b40d18b217af669eea9 > Author: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Date: Wed Apr 9 13:28:50 2014 +0300 > > drm/i915/chv: Make CHV irq handler loop until all interrupts are consumed > > as under continuous execlists load we can saturate the IRQ handler, > destablising the tsc clock and triggering the NMI watchdog to declare a hung > CPU. > > [ 552.756051] clocksource: timekeeping watchdog on CPU0: Marking > clocksource 'tsc' as unstable because the skew is too large: > [ 552.756080] clocksource: 'refined-jiffies' wd_now: 10003b480 > wd_last: 10003b28c mask: ffffffff > [ 552.756091] clocksource: 'tsc' cs_now: d55d31aa50 cs_last: > d17446166c mask: ffffffffffffffff > [ 552.756210] clocksource: Switched to clocksource refined-jiffies > [ 575.217870] NMI watchdog: Watchdog detected hard LOCKUP on cpu 1 > [ 575.217893] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.5.0-rc7+ #18 > [ 575.217905] Hardware name: /NUC5CPYB, BIOS > PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015 > [ 575.217915] 0000000000000000 ffff88027fd05bc0 ffffffff81288c6d > 0000000000000000 > [ 575.217935] 0000000000000001 ffff88027fd05be0 ffffffff810e72d1 > 0000000000000000 > [ 575.217951] ffff88027fd05c80 ffff88027fd05c20 ffffffff81114b60 > 0000000181015f1e > [ 575.217967] Call Trace: > [ 575.217973] <NMI> [<ffffffff81288c6d>] dump_stack+0x4f/0x72 > [ 575.217994] [<ffffffff810e72d1>] > watchdog_overflow_callback+0x151/0x160 > [ 575.218003] [<ffffffff81114b60>] __perf_event_overflow+0xa0/0x1e0 > [ 575.218016] [<ffffffff811154c4>] perf_event_overflow+0x14/0x20 > [ 575.218028] [<ffffffff8101d2ca>] intel_pmu_handle_irq+0x1da/0x460 > [ 575.218042] [<ffffffff814a8aae>] ? poll_idle+0x3e/0x70 > [ 575.218052] [<ffffffff814a8aae>] ? poll_idle+0x3e/0x70 > [ 575.218064] [<ffffffff81014ae8>] perf_event_nmi_handler+0x28/0x50 > [ 575.218075] [<ffffffff81007540>] nmi_handle+0x60/0x130 > [ 575.218086] [<ffffffff814a8aae>] ? poll_idle+0x3e/0x70 > [ 575.218096] [<ffffffff810079c0>] do_nmi+0x140/0x470 > [ 575.218108] [<ffffffff81559ec7>] end_repeat_nmi+0x1a/0x1e > [ 575.218119] [<ffffffff814a8aae>] ? poll_idle+0x3e/0x70 > [ 575.218129] [<ffffffff814a8aae>] ? poll_idle+0x3e/0x70 > [ 575.218139] [<ffffffff814a8aae>] ? poll_idle+0x3e/0x70 > [ 575.218148] <<EOE>> [<ffffffff814a8353>] > cpuidle_enter_state+0xf3/0x2f0 > [ 575.218164] [<ffffffff814a8587>] cpuidle_enter+0x17/0x20 > [ 575.218175] [<ffffffff810aaa3a>] call_cpuidle+0x2a/0x40 > [ 575.218185] [<ffffffff810aade3>] cpu_startup_entry+0x273/0x330 > [ 575.218196] [<ffffffff81033a1e>] start_secondary+0x10e/0x130 > > However, not servicing all available IIR within the handler does hurt the > throughput of pathological nop execbuf by about 20%, with a similar effect > upon the dispatch latency of a series of execbuf. > > v2: use do {} while(0) for a smaller patch, and easier to revert again > > I have reasonable confidence that we do not miss GT interrupts (as > execlists provides a stress case with a failure mechanism easily > detected by igt), however I have less confidence about all the other > sources of interrupts and worry that may lose a display hotplug > interrupt, for example. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93467 > Testcase: igt/gem_exec_nop/basic # requires NMI watchdog > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Cc: Antti Koskipää <antti.koskipaa@xxxxxxxxxxxxxxx> > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Link: http://patchwork.freedesktop.org/patch/msgid/1457946117-6714-1-git- > send-email-chris@xxxxxxxxxxxxxxxxxx > Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_irq.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_irq.c > b/drivers/gpu/drm/i915/i915_irq.c > index 6a51bc6..6f453fe 100644 > --- a/drivers/gpu/drm/i915/i915_irq.c > +++ b/drivers/gpu/drm/i915/i915_irq.c > @@ -1837,7 +1837,7 @@ static irqreturn_t cherryview_irq_handler(int irq, > void *arg) > if (!intel_irqs_enabled(dev_priv)) > return IRQ_NONE; > > - for (;;) { > + do { > master_ctl = I915_READ(GEN8_MASTER_IRQ) & > ~GEN8_MASTER_IRQ_CONTROL; > iir = I915_READ(VLV_IIR); > > @@ -1865,7 +1865,7 @@ static irqreturn_t cherryview_irq_handler(int irq, > void *arg) > > I915_WRITE(GEN8_MASTER_IRQ, > DE_MASTER_IRQ_CONTROL); > POSTING_READ(GEN8_MASTER_IRQ); > - } > + } while (0); > > return ret; > } > -- > 2.7.4 ��.n��������+%������w��{.n�����������ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f