On Mon, 27 Mar 2017 18:02:13 +0200, Takashi Iwai wrote: > > Hi, > > the upstream fix a16b7658f4e0d4aec9bc3e75a5f0cc3f7a3a0422 > drm/i915: Call intel_dp_mst_resume() before resuming displays > > seems to trigger a kernel panic when some modeset change happens after > S3 resume. The details are found in openSUSE bugzilla, > https://bugzilla.suse.com/show_bug.cgi?id=1029634 > > In short, the following procedure causes a kernel panic (supposedly) > almost 100% on Dell Latitude with Skylake with MST DP on dock: > > - Boot with a docking station, DP-1 connected. > - Login on X > - xrandr --output eDP-1 --primary --auto --output DP-1-1 --auto --left-of eDP-1 > ==> This changes the mode. > - Suspend ("systemctl suspend" in my case), and close the lid. > - Remove from the dock (keep the lid closed). > - Open the lid, which resumes automatically. It works. > - Suspend again. > - Connect to the dock again (keep the lid closed). > - Open the lid, which resumes automatically. It's still OK. > - xrandr --output eDP-1 --primary --auto --output DP-1-1 --auto --left-of eDP-1 > ==> Now the kernel feezes. > > Reverting the commit mentioned above fixes the problem. > > The problem is present in all versions I tested. The reported kernel > in the Bugzilla is 4.4.x-based one, but the issue is seen in 4.11-rc3, > too. Note that the S3 resume itself works in 4.11-rc3; the kernel > panic happens when invoking xrandr manually after that. > > Unfortunately, I couldn't get a kernel panic message, so far. kdump > didn't work well in this case by some reason. There are some > screenshots taken by the original reporter (could switch VT > beforehand), but I don't know whether it helps. > > If you have any hints for further debugging, it'd be highly > appreciated. It seems that the patch below works around the problem. Can anyone enlighten what's going on there? thanks, Takashi -- 8< -- From: Takashi Iwai <tiwai@xxxxxxx> Subject: [PATCH] drm/i915: Fix crash after S3 resume with DP MST mode change We've got a bug report showing that Skylake Dell machines with a docking station causes a kernel panic after S3 resume and modeset. The details are found in the openSUSE bugzilla entry below. The typical test procedure is: - Laptop is Dell Latitude with eDP (1366x768) - Boot with docking station connected to a DP (1920x1080) - Login, change the mode via xrandr --output eDP-1 --auto --output DP-1-1 --auto --left-of eDP-1 - Suspend, and close the lid after the suspend (or close the lid to trigger the suspend) - Undock while keeping the lid closed. - Open the lid, which triggers the resume; the machine wakes up well, and X shows up. No problem, so far. - Suspend again, close the lid. - Dock again while keeping the lid closed. - Open the lid, triggering the resume; this wakes up still fine. - At this moment, run xrandr again to re-setup DP-1 xrandr --output eDP-1 --auto --output DP-1-1 --auto --left-of eDP-1 ==> This triggers a hard crash. I could bisect it, and this leaded to the commit a16b7658f4e0 ("drm/i915: Call intel_dp_mst_resume() before resuming displays"). Basically the commit just shuffles the calls of intel_display_resume() and intel_dp_mst_resume(). So as a workaround, I tried to split intel_dp_mst_resume() call to postpone the suspected code (the invocation of intel_dp_check_mst_status()), then bingo, this cured the problem. But don't ask me *why* this fixes. It's still in a cargo-cult state. Fixes: a16b7658f4e0 ("drm/i915: Call intel_dp_mst_resume() before resuming displays") Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1029634 Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> --- drivers/gpu/drm/i915/i915_drv.c | 5 ++++- drivers/gpu/drm/i915/intel_dp.c | 20 +++++++++++++++++++- drivers/gpu/drm/i915/intel_drv.h | 3 ++- 3 files changed, 25 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 1c75402a59c1..62c40090ceed 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -1559,6 +1559,7 @@ static int i915_suspend_switcheroo(struct drm_device *dev, pm_message_t state) static int i915_drm_resume(struct drm_device *dev) { struct drm_i915_private *dev_priv = to_i915(dev); + int mst_pending; int ret; disable_rpm_wakeref_asserts(dev_priv); @@ -1608,10 +1609,12 @@ static int i915_drm_resume(struct drm_device *dev) dev_priv->display.hpd_irq_setup(dev_priv); spin_unlock_irq(&dev_priv->irq_lock); - intel_dp_mst_resume(dev); + mst_pending = intel_dp_mst_resume(dev); intel_display_resume(dev); + intel_dp_mst_resume_post(dev, mst_pending); + drm_kms_helper_poll_enable(dev); /* diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index d1670b8afbf5..fc5ea900e6f3 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -6027,9 +6027,10 @@ void intel_dp_mst_suspend(struct drm_device *dev) } } -void intel_dp_mst_resume(struct drm_device *dev) +int intel_dp_mst_resume(struct drm_device *dev) { struct drm_i915_private *dev_priv = to_i915(dev); + int pending = 0; int i; for (i = 0; i < I915_MAX_PORTS; i++) { @@ -6041,6 +6042,23 @@ void intel_dp_mst_resume(struct drm_device *dev) ret = drm_dp_mst_topology_mgr_resume(&intel_dig_port->dp.mst_mgr); if (ret) + pending |= 1 << i; + } + + return pending; +} + +void intel_dp_mst_resume_post(struct drm_device *dev, int pending) +{ + struct drm_i915_private *dev_priv = to_i915(dev); + int i; + + for (i = 0; i < I915_MAX_PORTS; i++) { + struct intel_digital_port *intel_dig_port = + dev_priv->hotplug.irq_port[i]; + if (!intel_dig_port || !intel_dig_port->dp.can_mst) + continue; + if (pending & (1 << i)) intel_dp_check_mst_status(&intel_dig_port->dp); } } diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 344f238b283f..2025aafdcd26 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -1447,7 +1447,8 @@ void intel_edp_panel_on(struct intel_dp *intel_dp); void intel_edp_panel_off(struct intel_dp *intel_dp); void intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *connector); void intel_dp_mst_suspend(struct drm_device *dev); -void intel_dp_mst_resume(struct drm_device *dev); +int intel_dp_mst_resume(struct drm_device *dev); +void intel_dp_mst_resume_post(struct drm_device *dev, int pending); int intel_dp_max_link_rate(struct intel_dp *intel_dp); int intel_dp_rate_select(struct intel_dp *intel_dp, int rate); void intel_dp_hot_plug(struct intel_encoder *intel_encoder); -- 2.11.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
