Re: [PATCH 3/7] drm/i915: don't read pp_ctrl_reg if we're suspended

Daniel Vetter
2014-04-01T20:53:04Z

On Tue, Apr 01, 2014 at 05:48:15PM -0300, Paulo Zanoni wrote:
> 2014-04-01 17:37 GMT-03:00 Daniel Vetter <daniel@ffwll.ch>:
> > On Tue, Apr 01, 2014 at 02:55:09PM -0300, Paulo Zanoni wrote:
> >> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
> >>
> >> ... at edp_have_panel_vdd. Just return false, saying we don't have the
> >> panel VDD since the device is suspended.
> >>
> >> We started getting WARNs about this problem since the patch that
> >> started checking if we're suspended while reading registers.
> >>
> >> Testcase: igt/pm_pc8
> >> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> >
> > Hm, where's an example backtrace for this? I wonder whether we simply need
> > to extend the range where we hold the runtime pm ref a bit ...
>
> There are tons of WARNs, but here is one example:
>
> [ 63.572201] [drm:hsw_enable_pc8] Enabling package C8+
> [ 63.581831] [drm:i915_runtime_suspend] Device suspended
> [ 63.664798] ------------[ cut here ]------------
> [ 63.664824] WARNING: CPU: 3 PID: 828 at
> drivers/gpu/drm/i915/intel_uncore.c:47
> assert_device_not_suspended.isra.7+0x32/0x40 [i915]()
> [ 63.664826] Device suspended
> [ 63.664828] Modules linked in: ccm fuse ip6table_filter ip6_tables
> ebtable_nat ebtables arc4 ath9k_htc ath9k_common ath9k_hw mac80211 ath
> cfg80211 iTCO_wdt iTCO_vendor_support x86_pkg_temp_thermal coretemp
> microcode i2c_i801 e1000e pcspkr serio_raw lpc_ich ptp pps_core mei_me
> mei mfd_core dm_crypt i915 crc32_pclmul crc32c_intel
> ghash_clmulni_intel i2c_algo_bit drm_kms_helper drm video
> [ 63.664867] CPU: 3 PID: 828 Comm: kworker/3:3 Not tainted 3.14.0+ #153
> [ 63.664869] Hardware name: Intel Corporation Shark Bay Client
> platform/WhiteTip Mountain 1, BIOS HSWLPTU1.86C.0133.R00.1309172123
> 09/17/2013
> [ 63.664887] Workqueue: events edp_panel_vdd_work [i915]
> [ 63.664889] 0000000000000009 ffff88009d745c28 ffffffff8167ec6f
> ffff88009d745c70
> [ 63.664895] ffff88009d745c60 ffffffff8106c8ed ffff880036278000
> 00000000000c7204
> [ 63.664900] ffff88014f2d3040 ffff880036278070 0000000000000001
> ffff88009d745cc0
> [ 63.664905] Call Trace:
> [ 63.664911] [<ffffffff8167ec6f>] dump_stack+0x4d/0x66
> [ 63.664916] [<ffffffff8106c8ed>] warn_slowpath_common+0x7d/0xa0
> [ 63.664920] [<ffffffff8106c95c>] warn_slowpath_fmt+0x4c/0x50
> [ 63.664926] [<ffffffff810bd6be>] ? mark_held_locks+0xae/0x130
> [ 63.664941] [<ffffffffa00d80d2>]
> assert_device_not_suspended.isra.7+0x32/0x40 [i915]
> [ 63.664956] [<ffffffffa00d99d2>] gen6_read32+0x32/0x120 [i915]
> [ 63.664969] [<ffffffffa00d99a0>] ? gen6_read8+0x120/0x120 [i915]
> [ 63.664985] [<ffffffffa0106f8f>] edp_have_panel_vdd+0x3f/0x50 [i915]
> [ 63.665000] [<ffffffffa01074e8>] edp_panel_vdd_off_sync+0x58/0x1c0 [i915]
> [ 63.665004] [<ffffffff8108a06c>] ? process_one_work+0x18c/0x560
> [ 63.665018] [<ffffffffa0107684>] edp_panel_vdd_work+0x34/0x50 [i915]
> [ 63.665022] [<ffffffff8108a0d7>] process_one_work+0x1f7/0x560
> [ 63.665026] [<ffffffff8108a06c>] ? process_one_work+0x18c/0x560
> [ 63.665031] [<ffffffff8108ae2b>] worker_thread+0x11b/0x3a0

Ah, that's the async edp worker thread. I guess we need to grab a runtim
pm ref when we start it and drop it again in the worker instead?

I'll add the backtrace to the commit, thanks.
-Daniel

> [ 63.665035] [<ffffffff8108ad10>] ? manage_workers.isra.21+0x2a0/0x2a0
> [ 63.665039] [<ffffffff810916fc>] kthread+0xfc/0x120
> [ 63.665043] [<ffffffff81091600>] ? kthread_create_on_node+0x230/0x230
> [ 63.665048] [<ffffffff8169082c>] ret_from_fork+0x7c/0xb0
> [ 63.665052] [<ffffffff81091600>] ? kthread_create_on_node+0x230/0x230
> [ 63.665054] ---[ end trace 1250bcc890af9999 ]---
> [ 63.665060] [drm:edp_panel_vdd_off_sync] Turning eDP VDD off
> [ 63.665061] ------------[ cut here ]------------
>
> >
> > Whatever, merged (I can rebase afterwards if you supply the backtrace for
> > the commit message, there we should at least have it).
> > -Daniel
> >> ---
> >> drivers/gpu/drm/i915/intel_dp.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> >> index 6f767e5..44471cc 100644
> >> --- a/drivers/gpu/drm/i915/intel_dp.c
> >> +++ b/drivers/gpu/drm/i915/intel_dp.c
> >> @@ -314,7 +314,8 @@ static bool edp_have_panel_vdd(struct intel_dp *intel_dp)
> >> struct drm_device *dev = intel_dp_to_dev(intel_dp);
> >> struct drm_i915_private *dev_priv = dev->dev_private;
> >>
> >> - return (I915_READ(_pp_ctrl_reg(intel_dp)) & EDP_FORCE_VDD) != 0;
> >> + return !dev_priv->pm.suspended &&
> >> + (I915_READ(_pp_ctrl_reg(intel_dp)) & EDP_FORCE_VDD) != 0;
> >> }
> >>
> >> static void
> >> --
> >> 1.8.5.3
> >>
> >> _______________________________________________
> >> Intel-gfx mailing list
> >> Intel-gfx@lists.freedesktop.org
> >> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > +41 (0) 79 365 57 48 - http://blog.ffwll.ch
>
>
>
> --
> Paulo Zanoni

--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch