From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Cc: Jani Nikula <jani.nikula@linux.intel.com>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, Rodrigo Vivi <rodrigo.vivi@intel.com>, David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, Thomas Gleixner <tglx@linutronix.de>, Mike Galbraith <umgwanakikbuti@gmail.com>, Sebastian Andrzej Siewior <bigeasy@linutronix.de> Subject: [PATCH 2/8] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates Date: Tue, 5 Oct 2021 17:00:40 +0200 [thread overview] Message-ID: <20211005150046.1000285-3-bigeasy@linutronix.de> (raw) In-Reply-To: <20211005150046.1000285-1-bigeasy@linutronix.de> From: Mike Galbraith <umgwanakikbuti@gmail.com> Commit 8d7849db3eab7 ("drm/i915: Make sprite updates atomic") started disabling interrupts across atomic updates. This breaks on PREEMPT_RT because within this section the code attempt to acquire spinlock_t locks which are sleeping locks on PREEMPT_RT. According to the comment the interrupts are disabled to avoid random delays and not required for protection or synchronisation. If this needs to happen with disabled interrupts on PREEMPT_RT, and the whole section is restricted to register access then all sleeping locks need to be acquired before interrupts are disabled and some function maybe moved after enabling interrupts again. This includes: - prepare_to_wait() + finish_wait() due its wake queue. - drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock. - skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and maybe others due to intel_uncore::lock - drm_crtc_arm_vblank_event() due to drm_device::event_lock and drm_device::vblank_time_lock. Don't disable interrupts on PREEMPT_RT during atomic updates. [bigeasy: drop local locks, commit message] Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/gpu/drm/i915/display/intel_crtc.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c index 254e67141a776..7a39029b083f4 100644 --- a/drivers/gpu/drm/i915/display/intel_crtc.c +++ b/drivers/gpu/drm/i915/display/intel_crtc.c @@ -425,7 +425,8 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state) */ intel_psr_wait_for_idle(new_crtc_state); - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); crtc->debug.min_vbl = min; crtc->debug.max_vbl = max; @@ -450,11 +451,13 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state) break; } - local_irq_enable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_enable(); timeout = schedule_timeout(timeout); - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); } finish_wait(wq, &wait); @@ -487,7 +490,8 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state) return; irq_disable: - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); } #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE) @@ -566,7 +570,8 @@ void intel_pipe_update_end(struct intel_crtc_state *new_crtc_state) new_crtc_state->uapi.event = NULL; } - local_irq_enable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_enable(); /* Send VRR Push to terminate Vblank */ intel_vrr_send_push(new_crtc_state); -- 2.33.0
WARNING: multiple messages have this Message-ID (diff)
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Cc: Jani Nikula <jani.nikula@linux.intel.com>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, Rodrigo Vivi <rodrigo.vivi@intel.com>, David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, Thomas Gleixner <tglx@linutronix.de>, Mike Galbraith <umgwanakikbuti@gmail.com>, Sebastian Andrzej Siewior <bigeasy@linutronix.de> Subject: [Intel-gfx] [PATCH 2/8] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates Date: Tue, 5 Oct 2021 17:00:40 +0200 [thread overview] Message-ID: <20211005150046.1000285-3-bigeasy@linutronix.de> (raw) In-Reply-To: <20211005150046.1000285-1-bigeasy@linutronix.de> From: Mike Galbraith <umgwanakikbuti@gmail.com> Commit 8d7849db3eab7 ("drm/i915: Make sprite updates atomic") started disabling interrupts across atomic updates. This breaks on PREEMPT_RT because within this section the code attempt to acquire spinlock_t locks which are sleeping locks on PREEMPT_RT. According to the comment the interrupts are disabled to avoid random delays and not required for protection or synchronisation. If this needs to happen with disabled interrupts on PREEMPT_RT, and the whole section is restricted to register access then all sleeping locks need to be acquired before interrupts are disabled and some function maybe moved after enabling interrupts again. This includes: - prepare_to_wait() + finish_wait() due its wake queue. - drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock. - skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and maybe others due to intel_uncore::lock - drm_crtc_arm_vblank_event() due to drm_device::event_lock and drm_device::vblank_time_lock. Don't disable interrupts on PREEMPT_RT during atomic updates. [bigeasy: drop local locks, commit message] Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/gpu/drm/i915/display/intel_crtc.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c index 254e67141a776..7a39029b083f4 100644 --- a/drivers/gpu/drm/i915/display/intel_crtc.c +++ b/drivers/gpu/drm/i915/display/intel_crtc.c @@ -425,7 +425,8 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state) */ intel_psr_wait_for_idle(new_crtc_state); - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); crtc->debug.min_vbl = min; crtc->debug.max_vbl = max; @@ -450,11 +451,13 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state) break; } - local_irq_enable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_enable(); timeout = schedule_timeout(timeout); - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); } finish_wait(wq, &wait); @@ -487,7 +490,8 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state) return; irq_disable: - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); } #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE) @@ -566,7 +570,8 @@ void intel_pipe_update_end(struct intel_crtc_state *new_crtc_state) new_crtc_state->uapi.event = NULL; } - local_irq_enable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_enable(); /* Send VRR Push to terminate Vblank */ intel_vrr_send_push(new_crtc_state); -- 2.33.0
next prev parent reply other threads:[~2021-10-05 15:00 UTC|newest] Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-05 15:00 [PATCH 0/8] drm/i915: PREEMPT_RT related fixups Sebastian Andrzej Siewior 2021-10-05 15:00 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-05 15:00 ` [PATCH 1/8] drm/i915: Use preempt_disable/enable_rt() where recommended Sebastian Andrzej Siewior 2021-10-05 15:00 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-05 15:00 ` Sebastian Andrzej Siewior [this message] 2021-10-05 15:00 ` [Intel-gfx] [PATCH 2/8] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates Sebastian Andrzej Siewior 2021-10-06 9:16 ` Ville Syrjälä 2021-10-05 15:00 ` [PATCH 3/8] drm/i915: Disable tracing points on PREEMPT_RT Sebastian Andrzej Siewior 2021-10-05 15:00 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-06 9:34 ` Ville Syrjälä 2021-10-06 9:34 ` [Intel-gfx] " Ville Syrjälä 2021-10-06 10:15 ` Sebastian Andrzej Siewior 2021-10-06 10:15 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-06 16:46 ` Sebastian Andrzej Siewior 2021-10-06 16:46 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-05 15:00 ` [PATCH 4/8] drm/i915: skip DRM_I915_LOW_LEVEL_TRACEPOINTS with NOTRACE Sebastian Andrzej Siewior 2021-10-05 15:00 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-05 15:00 ` [PATCH 5/8] drm/i915/gt: Queue and wait for the irq_work item Sebastian Andrzej Siewior 2021-10-05 15:00 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-05 15:00 ` [PATCH 6/8] drm/i915/gt: Use spin_lock_irq() instead of local_irq_disable() + spin_lock() Sebastian Andrzej Siewior 2021-10-05 15:00 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-05 15:00 ` [PATCH 7/8] drm/i915: Drop the irqs_disabled() check Sebastian Andrzej Siewior 2021-10-05 15:00 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-05 15:00 ` [PATCH 8/8] drm/i915: Don't disable interrupts and pretend a lock as been acquired in __timeline_mark_lock() Sebastian Andrzej Siewior 2021-10-05 15:00 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-05 19:16 ` Peter Zijlstra 2021-10-05 19:16 ` [Intel-gfx] " Peter Zijlstra 2021-10-06 6:58 ` Sebastian Andrzej Siewior 2021-10-06 6:58 ` [Intel-gfx] " Sebastian Andrzej Siewior 2021-10-08 6:21 ` [drm/i915] 511e5fb0c3: WARNING:suspicious_RCU_usage kernel test robot 2021-10-08 6:21 ` kernel test robot 2021-10-08 6:21 ` [Intel-gfx] " kernel test robot 2021-10-05 16:12 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/i915: PREEMPT_RT related fixups Patchwork 2021-10-05 16:48 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork 2021-10-06 17:41 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for drm/i915: PREEMPT_RT related fixups. (rev2) Patchwork
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