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Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0024-drm-i915-Don-t-disable-interrupts-on-PREEMPT_RT-duri.patch | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/debian/patches-rt/0024-drm-i915-Don-t-disable-interrupts-on-PREEMPT_RT-duri.patch b/debian/patches-rt/0024-drm-i915-Don-t-disable-interrupts-on-PREEMPT_RT-duri.patch new file mode 100644 index 000000000..c05066850 --- /dev/null +++ b/debian/patches-rt/0024-drm-i915-Don-t-disable-interrupts-on-PREEMPT_RT-duri.patch @@ -0,0 +1,91 @@ +From 7540de1a42a1a7409b4367b67c76480f7e96d25b Mon Sep 17 00:00:00 2001 +From: Mike Galbraith <umgwanakikbuti@gmail.com> +Date: Sat, 27 Feb 2016 09:01:42 +0100 +Subject: [PATCH 24/62] drm/i915: Don't disable interrupts on PREEMPT_RT during + atomic updates +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.1/older/patches-6.1.69-rt21.tar.xz + +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 6792a9056f46..43cedfef104f 100644 +--- a/drivers/gpu/drm/i915/display/intel_crtc.c ++++ b/drivers/gpu/drm/i915/display/intel_crtc.c +@@ -521,7 +521,8 @@ void intel_pipe_update_start(struct intel_crtc_state *new_crtc_state) + */ + intel_psr_wait_for_idle_locked(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; +@@ -546,11 +547,13 @@ void intel_pipe_update_start(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); +@@ -583,7 +586,8 @@ void intel_pipe_update_start(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) +@@ -684,7 +688,8 @@ void intel_pipe_update_end(struct intel_crtc_state *new_crtc_state) + */ + intel_vrr_send_push(new_crtc_state); + +- local_irq_enable(); ++ if (!IS_ENABLED(CONFIG_PREEMPT_RT)) ++ local_irq_enable(); + + if (intel_vgpu_active(dev_priv)) + return; +-- +2.43.0 + |