2024-01-22 17:57:19 +01:00
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From 725cdc8f12a18ee15bbc8eb0f44927a324e78f93 Mon Sep 17 00:00:00 2001
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2024-01-04 13:38:55 +01:00
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From: Mike Galbraith <umgwanakikbuti@gmail.com>
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Date: Sat, 27 Feb 2016 09:01:42 +0100
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Subject: [PATCH 24/62] drm/i915: Don't disable interrupts on PREEMPT_RT during
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atomic updates
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Commit
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8d7849db3eab7 ("drm/i915: Make sprite updates atomic")
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started disabling interrupts across atomic updates. This breaks on PREEMPT_RT
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because within this section the code attempt to acquire spinlock_t locks which
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are sleeping locks on PREEMPT_RT.
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According to the comment the interrupts are disabled to avoid random delays and
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not required for protection or synchronisation.
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If this needs to happen with disabled interrupts on PREEMPT_RT, and the
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whole section is restricted to register access then all sleeping locks
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need to be acquired before interrupts are disabled and some function
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maybe moved after enabling interrupts again.
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This includes:
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- prepare_to_wait() + finish_wait() due its wake queue.
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- drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock.
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- skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and
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maybe others due to intel_uncore::lock
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- drm_crtc_arm_vblank_event() due to drm_device::event_lock and
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drm_device::vblank_time_lock.
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Don't disable interrupts on PREEMPT_RT during atomic updates.
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[bigeasy: drop local locks, commit message]
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Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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drivers/gpu/drm/i915/display/intel_crtc.c | 15 ++++++++++-----
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1 file changed, 10 insertions(+), 5 deletions(-)
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diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
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index 6792a9056f46..43cedfef104f 100644
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--- a/drivers/gpu/drm/i915/display/intel_crtc.c
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+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
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@@ -521,7 +521,8 @@ void intel_pipe_update_start(struct intel_crtc_state *new_crtc_state)
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*/
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intel_psr_wait_for_idle_locked(new_crtc_state);
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- local_irq_disable();
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+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
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+ local_irq_disable();
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crtc->debug.min_vbl = min;
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crtc->debug.max_vbl = max;
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@@ -546,11 +547,13 @@ void intel_pipe_update_start(struct intel_crtc_state *new_crtc_state)
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break;
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}
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- local_irq_enable();
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+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
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+ local_irq_enable();
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timeout = schedule_timeout(timeout);
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- local_irq_disable();
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+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
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+ local_irq_disable();
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}
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finish_wait(wq, &wait);
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@@ -583,7 +586,8 @@ void intel_pipe_update_start(struct intel_crtc_state *new_crtc_state)
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return;
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irq_disable:
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- local_irq_disable();
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+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
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+ local_irq_disable();
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}
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#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
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@@ -684,7 +688,8 @@ void intel_pipe_update_end(struct intel_crtc_state *new_crtc_state)
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*/
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intel_vrr_send_push(new_crtc_state);
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- local_irq_enable();
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+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
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+ local_irq_enable();
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if (intel_vgpu_active(dev_priv))
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return;
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--
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2.43.0
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