From b3a0bbd37f5ac5309d09ab56ac461c0306582bdb Mon Sep 17 00:00:00 2001 From: "yang.yang29@zte.com.cn" Date: Fri, 9 Jun 2023 14:23:33 +0800 Subject: [PATCH 1/5] drm,radeon,i915: Use preempt_disable/enable_rt() where recommended commit 29ea2693d1daba2e6098b7b079a796945316d61d upstream. DRM folks identified the spots, so use them. Signed-off-by: Mike Galbraith Cc: Sebastian Andrzej Siewior Cc: linux-rt-users Signed-off-by: Thomas Gleixner --- drivers/gpu/drm/i915/i915_irq.c | 2 ++ drivers/gpu/drm/radeon/radeon_display.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 759f523c6a6b..7339a42ab2b8 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -847,6 +847,7 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, spin_lock_irqsave(&dev_priv->uncore.lock, irqflags); /* preempt_disable_rt() should go right here in PREEMPT_RT patchset. */ + preempt_disable_rt(); /* Get optional system timestamp before query. */ if (stime) @@ -898,6 +899,7 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, *etime = ktime_get(); /* preempt_enable_rt() should go right here in PREEMPT_RT patchset. */ + preempt_enable_rt(); spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c index 71bdafac9210..95ce311f434b 100644 --- a/drivers/gpu/drm/radeon/radeon_display.c +++ b/drivers/gpu/drm/radeon/radeon_display.c @@ -1823,6 +1823,7 @@ int radeon_get_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe, struct radeon_device *rdev = dev->dev_private; /* preempt_disable_rt() should go right here in PREEMPT_RT patchset. */ + preempt_disable_rt(); /* Get optional system timestamp before query. */ if (stime) @@ -1915,6 +1916,7 @@ int radeon_get_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe, *etime = ktime_get(); /* preempt_enable_rt() should go right here in PREEMPT_RT patchset. */ + preempt_enable_rt(); /* Decode into vertical and horizontal scanout position. */ *vpos = position & 0x1fff; -- Gitee From ecbd3a9325a0ceb1c6fd6cbbcaa12d71546d8ad9 Mon Sep 17 00:00:00 2001 From: "yang.yang29@zte.com.cn" Date: Fri, 9 Jun 2023 14:23:45 +0800 Subject: [PATCH 2/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates commit 8f6669784f0e3759750bb5966b3085e95b26264d upstream. 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. Don't disable interrupts on PREEMPT_RT during atomic updates. [bigeasy: drop local locks, commit message] Signed-off-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior --- drivers/gpu/drm/i915/display/intel_sprite.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c index 12f7128b777f..a65061e3e1d3 100644 --- a/drivers/gpu/drm/i915/display/intel_sprite.c +++ b/drivers/gpu/drm/i915/display/intel_sprite.c @@ -118,7 +118,8 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state) "PSR idle timed out 0x%x, atomic update may fail\n", psr_status); - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); crtc->debug.min_vbl = min; crtc->debug.max_vbl = max; @@ -143,11 +144,13 @@ 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); @@ -180,7 +183,8 @@ 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(); } /** @@ -218,7 +222,8 @@ 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(); if (intel_vgpu_active(dev_priv)) return; -- Gitee From 2b437d60bfba2a40520b08bcb444b4ee16b1790e Mon Sep 17 00:00:00 2001 From: "yang.yang29@zte.com.cn" Date: Fri, 9 Jun 2023 14:24:02 +0800 Subject: [PATCH 3/5] drm/i915: disable tracing on -RT commit 650ec72ae4ea9537fe72a559e14c6fe3cebfd429 upstream. Luca Abeni reported this: | BUG: scheduling while atomic: kworker/u8:2/15203/0x00000003 | CPU: 1 PID: 15203 Comm: kworker/u8:2 Not tainted 4.19.1-rt3 #10 | Call Trace: | rt_spin_lock+0x3f/0x50 | gen6_read32+0x45/0x1d0 [i915] | g4x_get_vblank_counter+0x36/0x40 [i915] | trace_event_raw_event_i915_pipe_update_start+0x7d/0xf0 [i915] The tracing events use trace_i915_pipe_update_start() among other events use functions acquire spin locks. A few trace points use intel_get_crtc_scanline(), others use ->get_vblank_counter() wich also might acquire a sleeping lock. Based on this I don't see any other way than disable trace points on RT. Cc: stable-rt@vger.kernel.org Reported-by: Luca Abeni Signed-off-by: Sebastian Andrzej Siewior --- drivers/gpu/drm/i915/i915_trace.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h index a4addcc64978..0ba5a0a0fd25 100644 --- a/drivers/gpu/drm/i915/i915_trace.h +++ b/drivers/gpu/drm/i915/i915_trace.h @@ -2,6 +2,10 @@ #if !defined(_I915_TRACE_H_) || defined(TRACE_HEADER_MULTI_READ) #define _I915_TRACE_H_ +#ifdef CONFIG_PREEMPT_RT +#define NOTRACE +#endif + #include #include #include -- Gitee From 2c8191aaff4b7a6247c9832144da10366a858ff1 Mon Sep 17 00:00:00 2001 From: "yang.yang29@zte.com.cn" Date: Fri, 9 Jun 2023 14:24:12 +0800 Subject: [PATCH 4/5] drm/i915: skip DRM_I915_LOW_LEVEL_TRACEPOINTS with NOTRACE commit c5f247c733a6b6cced5ab52f1c218df4bf313c68 upstream. The order of the header files is important. If this header file is included after tracepoint.h was included then the NOTRACE here becomes a nop. Currently this happens for two .c files which use the tracepoitns behind DRM_I915_LOW_LEVEL_TRACEPOINTS. Signed-off-by: Sebastian Andrzej Siewior --- drivers/gpu/drm/i915/i915_trace.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h index 0ba5a0a0fd25..396b6598694d 100644 --- a/drivers/gpu/drm/i915/i915_trace.h +++ b/drivers/gpu/drm/i915/i915_trace.h @@ -782,7 +782,7 @@ DEFINE_EVENT(i915_request, i915_request_add, TP_ARGS(rq) ); -#if defined(CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS) +#if defined(CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS) && !defined(NOTRACE) DEFINE_EVENT(i915_request, i915_request_submit, TP_PROTO(struct i915_request *rq), TP_ARGS(rq) -- Gitee From 851a0c288ccd810aa848314ba59e6612c88bc9a0 Mon Sep 17 00:00:00 2001 From: "yang.yang29@zte.com.cn" Date: Fri, 9 Jun 2023 14:24:21 +0800 Subject: [PATCH 5/5] drm/i915/gt: Only disable interrupts for the timeline lock on !force-threaded commit f976696bf81de3206f9a264edc78281a0084dd46 upstream. According to commit d67739268cf0e ("drm/i915/gt: Mark up the nested engine-pm timeline lock as irqsafe") the intrrupts are disabled the code may be called from an interrupt handler and from preemptible context. With `force_irqthreads' set the timeline mutex is never observed in IRQ context so it is not neede to disable interrupts. Disable only interrupts if not in `force_irqthreads' mode. Signed-off-by: Sebastian Andrzej Siewior --- drivers/gpu/drm/i915/gt/intel_engine_pm.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c index f7b2e07e2229..313d8a28e776 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c @@ -60,9 +60,10 @@ static int __engine_unpark(struct intel_wakeref *wf) static inline unsigned long __timeline_mark_lock(struct intel_context *ce) { - unsigned long flags; + unsigned long flags = 0; - local_irq_save(flags); + if (!force_irqthreads) + local_irq_save(flags); mutex_acquire(&ce->timeline->mutex.dep_map, 2, 0, _THIS_IP_); return flags; @@ -72,7 +73,8 @@ static inline void __timeline_mark_unlock(struct intel_context *ce, unsigned long flags) { mutex_release(&ce->timeline->mutex.dep_map, _THIS_IP_); - local_irq_restore(flags); + if (!force_irqthreads) + local_irq_restore(flags); } #else -- Gitee