Had some discussion with Daniel on IRC about how we can fix the deadlock. We couldn't decide upon any solution but I can give it a try. He suggested to have a work function for ->hot_plug which will get the power domain lock and not allow ->hot_plug if the power_domain is shut. Then when it calls hpt_init again from power_domain get, ->hot_plug gets called. But this looks racy, we can try this out. If there are any other suggestions, please let me know. I will work on this after 26th Oct. Regards, Sonika -----Original Message----- From: Sharma, Shashank Sent: Monday, October 12, 2015 5:54 PM To: Ville Syrjälä; Vetter, Daniel Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Mukherjee, Indranil; Jindal, Sonika Subject: RE: [PATCH 1/2] drm/i915: Call encoder hotplug for init and resume cases We were debugging this issue, and we could find the root cause: In function: Intel_hpd_init() | encoder->hotplug() | display_power_get() | Intel_powe_well_enable() | power_well->ops->enable() | chv_pipe_power_well_enable() | vlv_display_power_well_init() | intel_hdp_init() This function ends up calling intel_hpd_init, Which is causing the mutex deadlock due to recursion, as we are calling encoder->hotplug() from hpd_init(). Intel_hpd_init() | encoder->hotplug() | display_power_get() There are two solutions here: - remove hpd_init() from get_calls - remove encoder->hotplug() function call from hpd_init() and put it in some other place. We have added this function from encoder_init() for android trees, and it works well there. Regards Shashank -----Original Message----- From: Intel-gfx [mailto:intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Ville Syrjälä Sent: Thursday, October 08, 2015 7:06 PM To: Jindal, Sonika Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx Subject: Re: [PATCH 1/2] drm/i915: Call encoder hotplug for init and resume cases On Mon, Oct 05, 2015 at 04:43:14PM +0530, Sonika Jindal wrote: > For all the encoders, call the hot_plug if it is registered. > This is required for connected boot and resume cases to generate fake > hpd resulting in reading of edid. > Removing the initial sdvo hot_plug call too so that it will be called > just once from this loop. > > Signed-off-by: Sonika Jindal <sonika.jindal@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_hotplug.c | 11 +++++++++++ > drivers/gpu/drm/i915/intel_sdvo.c | 1 - > 2 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/intel_hotplug.c > b/drivers/gpu/drm/i915/intel_hotplug.c > index 53c0173..eac4757 100644 > --- a/drivers/gpu/drm/i915/intel_hotplug.c > +++ b/drivers/gpu/drm/i915/intel_hotplug.c > @@ -458,6 +458,7 @@ void intel_hpd_init(struct drm_i915_private > *dev_priv) { > struct drm_device *dev = dev_priv->dev; > struct drm_mode_config *mode_config = &dev->mode_config; > + struct intel_encoder *encoder; > struct drm_connector *connector; > int i; > > @@ -482,6 +483,16 @@ void intel_hpd_init(struct drm_i915_private *dev_priv) > if (dev_priv->display.hpd_irq_setup) > dev_priv->display.hpd_irq_setup(dev); > spin_unlock_irq(&dev_priv->irq_lock); > + > + /* > + * Connected boot / resume scenarios can't generate new hot plug. > + * So, probe it manually. > + */ > + list_for_each_entry(encoder, &dev->mode_config.encoder_list, > + base.head) { > + if (encoder->hot_plug) > + encoder->hot_plug(encoder); > + } This breaks the world on CHV [ 3187.575198] [drm:intel_hdmi_hot_plug] Live status not up! [ 3187.585154] ============================================= [ 3187.595010] [ INFO: possible recursive locking detected ] [ 3187.604685] 4.3.0-rc4-bsw+ #2488 Tainted: G U W [ 3187.614366] --------------------------------------------- [ 3187.623892] Xorg/32212 is trying to acquire lock: [ 3187.632635] (&power_domains->lock){+.+...}, at: [<ffffffffa036aced>] intel_display_power_get+0x38/0xcb [i915] [ 3187.647492] [ 3187.647492] but task is already holding lock: [ 3187.661054] (&power_domains->lock){+.+...}, at: [<ffffffffa036aced>] intel_display_power_get+0x38/0xcb [i915] [ 3187.675960] [ 3187.675960] other info that might help us debug this: [ 3187.690459] Possible unsafe locking scenario: [ 3187.690459] [ 3187.704224] CPU0 [ 3187.710485] ---- [ 3187.716711] lock(&power_domains->lock); [ 3187.724718] lock(&power_domains->lock); [ 3187.732663] [ 3187.732663] *** DEADLOCK *** [ 3187.732663] [ 3187.749460] May be due to missing lock nesting notation [ 3187.749460] [ 3187.763833] 5 locks held by Xorg/32212: [ 3187.771523] #0: (drm_global_mutex){+.+.+.}, at: [<ffffffffa02ad5c8>] drm_release+0x3b/0x49b [drm] [ 3187.785216] #1: (&dev->mode_config.mutex){+.+.+.}, at: [<ffffffffa02c4d85>] drm_modeset_lock_all+0x54/0xcd [drm] [ 3187.800437] #2: (crtc_ww_class_acquire){+.+.+.}, at: [<ffffffffa02c4d8f>] drm_modeset_lock_all+0x5e/0xcd [drm] [ 3187.815488] #3: (crtc_ww_class_mutex){+.+.+.}, at: [<ffffffffa02c46b0>] drm_modeset_lock+0x75/0xfc [drm] [ 3187.830094] #4: (&power_domains->lock){+.+...}, at: [<ffffffffa036aced>] intel_display_power_get+0x38/0xcb [i915] [ 3187.845534] [ 3187.845534] stack backtrace: [ 3187.857685] CPU: 2 PID: 32212 Comm: Xorg Tainted: G U W 4.3.0-rc4-bsw+ #2488 [ 3187.870331] Hardware name: Intel Corporation CHERRYVIEW C0 PLATFORM/Braswell CRB, BIOS BRAS.X64.B085.R00.1509110553 09/11/2015 [ 3187.886827] 0000000000000000 ffff880175eff8e0 ffffffff8128d59e ffffffff823f5ee0 [ 3187.898904] ffff880175eff958 ffffffff810a7a08 0000000000000000 ffff880179d1c5d0 [ 3187.910954] 0000000000000004 0000000000000006 45422a91588a4c3e 0000000000000005 [ 3187.923011] Call Trace: [ 3187.929451] [<ffffffff8128d59e>] dump_stack+0x4e/0x79 [ 3187.938912] [<ffffffff810a7a08>] __lock_acquire+0x7ab/0x12af [ 3187.949027] [<ffffffff810a8d04>] lock_acquire+0x10e/0x1a9 [ 3187.958859] [<ffffffffa036aced>] ? intel_display_power_get+0x38/0xcb [i915] [ 3187.970476] [<ffffffffa036aced>] ? intel_display_power_get+0x38/0xcb [i915] [ 3187.982011] [<ffffffff814df4a3>] mutex_lock_nested+0x71/0x346 [ 3187.992167] [<ffffffffa036aced>] ? intel_display_power_get+0x38/0xcb [i915] [ 3188.003655] [<ffffffff814e20ee>] ? _raw_spin_unlock_irqrestore+0x4b/0x60 [ 3188.014829] [<ffffffff81364565>] ? __pm_runtime_resume+0x71/0x7e [ 3188.025269] [<ffffffffa036aced>] intel_display_power_get+0x38/0xcb [i915] [ 3188.036544] [<ffffffffa036aced>] ? intel_display_power_get+0x38/0xcb [i915] [ 3188.047968] [<ffffffffa03e8cc4>] intel_hdmi_set_edid+0x3f/0xd6 [i915] [ 3188.058766] [<ffffffffa03e8e1a>] intel_hdmi_hot_plug+0xbf/0xfb [i915] [ 3188.069484] [<ffffffffa03c9e78>] intel_hpd_init+0xfa/0x10b [i915] [ 3188.079753] [<ffffffffa036968d>] vlv_display_power_well_init+0xdb/0xe8 [i915] [ 3188.091224] [<ffffffffa0369763>] chv_pipe_power_well_enable+0x62/0x67 [i915] [ 3188.102594] [<ffffffffa036ad55>] intel_display_power_get+0xa0/0xcb [i915] [ 3188.113657] [<ffffffffa03bdd7a>] modeset_get_crtc_power_domains+0x11d/0x13c [i915] [ 3188.125589] [<ffffffffa03bdfc1>] intel_atomic_commit+0x228/0xf1b [i915] [ 3188.136522] [<ffffffffa02c586c>] ? drm_atomic_check_only+0x37b/0x4da [drm] [ 3188.147676] [<ffffffffa02c5a18>] drm_atomic_commit+0x4d/0x52 [drm] [ 3188.158023] [<ffffffffa032fa25>] restore_fbdev_mode+0x11e/0x286 [drm_kms_helper] [ 3188.169734] [<ffffffffa0331443>] drm_fb_helper_restore_fbdev_mode_unlocked+0x36/0x6d [drm_kms_helper] [ 3188.183557] [<ffffffffa03d270f>] intel_fbdev_restore_mode+0x22/0x7a [i915] [ 3188.194701] [<ffffffffa03f70b8>] i915_driver_lastclose+0xe/0x15 [i915] [ 3188.205361] [<ffffffffa02ad4c2>] drm_lastclose+0x3f/0x10a [drm] [ 3188.215323] [<ffffffffa02ad9ee>] drm_release+0x461/0x49b [drm] [ 3188.225195] [<ffffffff8118577c>] __fput+0x100/0x1b3 [ 3188.233956] [<ffffffff81185865>] ____fput+0xe/0x10 [ 3188.242594] [<ffffffff81084540>] task_work_run+0x6a/0x93 [ 3188.251816] [<ffffffff810015d6>] prepare_exit_to_usermode+0x9e/0xaf [ 3188.262111] [<ffffffff810017d6>] syscall_return_slowpath+0x1ef/0x264 [ 3188.272486] [<ffffffff81084462>] ? task_work_add+0x44/0x53 [ 3188.281885] [<ffffffff811858e3>] ? fput+0x7c/0x83 [ 3188.290389] [<ffffffff810a6e52>] ? trace_hardirqs_on_caller+0x16/0x196 [ 3188.300941] [<ffffffff81000c87>] ? trace_hardirqs_on_thunk+0x17/0x19 [ 3188.311245] [<ffffffff814e2ab1>] int_ret_from_sys_call+0x25/0x9f > } > > void intel_hpd_init_work(struct drm_i915_private *dev_priv) diff > --git a/drivers/gpu/drm/i915/intel_sdvo.c > b/drivers/gpu/drm/i915/intel_sdvo.c > index 05521b5..55859e9 100644 > --- a/drivers/gpu/drm/i915/intel_sdvo.c > +++ b/drivers/gpu/drm/i915/intel_sdvo.c > @@ -2433,7 +2433,6 @@ intel_sdvo_dvi_init(struct intel_sdvo *intel_sdvo, int device) > * Ensure that they get re-enabled when an interrupt happens. > */ > intel_encoder->hot_plug = intel_sdvo_enable_hotplug; > - intel_sdvo_enable_hotplug(intel_encoder); > } else { > intel_connector->polled = DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT; > } > -- > 1.7.10.4 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
