From 3dd14c04d77d7d702de5aa7157df4cc9417329f3 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 21 Apr 2017 14:58:15 +0100 Subject: [PATCH] drm/i915: Avoid busy-spinning on VLV_GLTC_PW_STATUS mmio MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The busy-spin, as the first stage of intel_wait_for_register(), is currently under suspicion for causing: [ 62.034926] NMI watchdog: Watchdog detected hard LOCKUP on cpu 1 [ 62.034928] Modules linked in: i2c_dev i915 intel_gtt drm_kms_helper prime_numbers [ 62.034932] CPU: 1 PID: 183 Comm: kworker/1:2 Not tainted 4.11.0-rc7+ #471 [ 62.034933] Hardware name: / , BIOS PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015 [ 62.034934] Workqueue: pm pm_runtime_work [ 62.034936] task: ffff880275a04ec0 task.stack: ffffc900002d8000 [ 62.034936] RIP: 0010:__intel_wait_for_register_fw+0x77/0x1a0 [i915] [ 62.034937] RSP: 0018:ffffc900002dbc38 EFLAGS: 00000082 [ 62.034939] RAX: ffffc90003530094 RBX: 0000000000130094 RCX: 0000000000000001 [ 62.034940] RDX: 00000000000000a1 RSI: ffff88027fd15e58 RDI: 0000000000000000 [ 62.034941] RBP: ffffc900002dbc78 R08: 0000000000000002 R09: 0000000000000000 [ 62.034942] R10: ffffc900002dbc18 R11: ffff880276429dd0 R12: ffff8802707c0000 [ 62.034943] R13: 00000000000000a0 R14: 0000000000000000 R15: 00000000fffefc10 [ 62.034945] FS: 0000000000000000(0000) GS:ffff88027fd00000(0000) knlGS:0000000000000000 [ 62.034945] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 62.034947] CR2: 00007ffd3cd98ff8 CR3: 0000000274c19000 CR4: 00000000001006e0 [ 62.034947] Call Trace: [ 62.034948] intel_wait_for_register+0x77/0x140 [i915] [ 62.034949] vlv_suspend_complete+0x23/0x5b0 [i915] [ 62.034950] intel_runtime_suspend+0x16c/0x2a0 [i915] [ 62.034950] pci_pm_runtime_suspend+0x50/0x180 [ 62.034951] ? pci_pm_runtime_resume+0xa0/0xa0 [ 62.034952] __rpm_callback+0xc5/0x210 [ 62.034953] rpm_callback+0x1f/0x80 [ 62.034953] ? pci_pm_runtime_resume+0xa0/0xa0 [ 62.034954] rpm_suspend+0x118/0x580 [ 62.034955] pm_runtime_work+0x64/0x90 [ 62.034956] process_one_work+0x1bb/0x3e0 [ 62.034956] worker_thread+0x46/0x4f0 [ 62.034957] ? __schedule+0x18b/0x610 [ 62.034958] kthread+0xff/0x140 [ 62.034958] ? process_one_work+0x3e0/0x3e0 [ 62.034959] ? kthread_create_on_node+ and related hard lockups in CI for byt and bsw. Note this effectively reverts commits 41ce405e6894 and b27366958869 ("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()") v2: Convert bool allow into a u32 mask for clarity and repeat the comment on vlv rc6 timing to justify the 3ms timeout used for the wait (Ville) Fixes: 41ce405e6894 ("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()") Fixes: b27366958869 ("drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()") Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100718 Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Cc: Ville Syrjälä Cc: Tomi Sarvela Reviewed-by: Ville Syrjälä Link: http://patchwork.freedesktop.org/patch/msgid/20170421135815.11897-1-chris@chris-wilson.co.uk Tested-by: Tomi Sarvela --- drivers/gpu/drm/i915/i915_drv.c | 46 +++++++++++++++++---------------- 1 file changed, 24 insertions(+), 22 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index cc7393e65e99..c7d68e789642 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -2175,6 +2175,20 @@ static void vlv_restore_gunit_s0ix_state(struct drm_i915_private *dev_priv) I915_WRITE(VLV_GUNIT_CLOCK_GATE2, s->clock_gate_dis2); } +static int vlv_wait_for_pw_status(struct drm_i915_private *dev_priv, + u32 mask, u32 val) +{ + /* The HW does not like us polling for PW_STATUS frequently, so + * use the sleeping loop rather than risk the busy spin within + * intel_wait_for_register(). + * + * Transitioning between RC6 states should be at most 2ms (see + * valleyview_enable_rps) so use a 3ms timeout. + */ + return wait_for((I915_READ_NOTRACE(VLV_GTLC_PW_STATUS) & mask) == val, + 3); +} + int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool force_on) { u32 val; @@ -2203,8 +2217,9 @@ int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool force_on) static int vlv_allow_gt_wake(struct drm_i915_private *dev_priv, bool allow) { + u32 mask; u32 val; - int err = 0; + int err; val = I915_READ(VLV_GTLC_WAKE_CTRL); val &= ~VLV_GTLC_ALLOWWAKEREQ; @@ -2213,45 +2228,32 @@ static int vlv_allow_gt_wake(struct drm_i915_private *dev_priv, bool allow) I915_WRITE(VLV_GTLC_WAKE_CTRL, val); POSTING_READ(VLV_GTLC_WAKE_CTRL); - err = intel_wait_for_register(dev_priv, - VLV_GTLC_PW_STATUS, - VLV_GTLC_ALLOWWAKEACK, - allow, - 1); + mask = VLV_GTLC_ALLOWWAKEACK; + val = allow ? mask : 0; + + err = vlv_wait_for_pw_status(dev_priv, mask, val); if (err) DRM_ERROR("timeout disabling GT waking\n"); return err; } -static int vlv_wait_for_gt_wells(struct drm_i915_private *dev_priv, - bool wait_for_on) +static void vlv_wait_for_gt_wells(struct drm_i915_private *dev_priv, + bool wait_for_on) { u32 mask; u32 val; - int err; mask = VLV_GTLC_PW_MEDIA_STATUS_MASK | VLV_GTLC_PW_RENDER_STATUS_MASK; val = wait_for_on ? mask : 0; - if ((I915_READ(VLV_GTLC_PW_STATUS) & mask) == val) - return 0; - - DRM_DEBUG_KMS("waiting for GT wells to go %s (%08x)\n", - onoff(wait_for_on), - I915_READ(VLV_GTLC_PW_STATUS)); /* * RC6 transitioning can be delayed up to 2 msec (see * valleyview_enable_rps), use 3 msec for safety. */ - err = intel_wait_for_register(dev_priv, - VLV_GTLC_PW_STATUS, mask, val, - 3); - if (err) + if (vlv_wait_for_pw_status(dev_priv, mask, val)) DRM_ERROR("timeout waiting for GT wells to go %s\n", onoff(wait_for_on)); - - return err; } static void vlv_check_no_gt_access(struct drm_i915_private *dev_priv) @@ -2272,7 +2274,7 @@ static int vlv_suspend_complete(struct drm_i915_private *dev_priv) * Bspec defines the following GT well on flags as debug only, so * don't treat them as hard failures. */ - (void)vlv_wait_for_gt_wells(dev_priv, false); + vlv_wait_for_gt_wells(dev_priv, false); mask = VLV_GTLC_RENDER_CTX_EXISTS | VLV_GTLC_MEDIA_CTX_EXISTS; WARN_ON((I915_READ(VLV_GTLC_WAKE_CTRL) & mask) != mask); -- 2.20.1