From d2944cf21305c754fa8b2d6c1eea05ad5dad7944 Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst Date: Tue, 11 Aug 2015 12:31:11 +0200 Subject: [PATCH] drm/i915: Commit planes on each crtc separately. This patch is based on the upstream commit 5ac1c4bcf073ad and amended for v4.2 to make sure it works as intended. Repeated calls to begin_crtc_commit can cause warnings like this: [ 169.127746] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:616 [ 169.127835] in_atomic(): 0, irqs_disabled(): 1, pid: 1947, name: kms_flip [ 169.127840] 3 locks held by kms_flip/1947: [ 169.127843] #0: (&dev->mode_config.mutex){+.+.+.}, at: [] __drm_modeset_lock_all+0x9c/0x130 [ 169.127860] #1: (crtc_ww_class_acquire){+.+.+.}, at: [] __drm_modeset_lock_all+0xad/0x130 [ 169.127870] #2: (crtc_ww_class_mutex){+.+.+.}, at: [] drm_modeset_lock+0x38/0x110 [ 169.127879] irq event stamp: 665690 [ 169.127882] hardirqs last enabled at (665689): [] _raw_spin_unlock_irqrestore+0x55/0x70 [ 169.127889] hardirqs last disabled at (665690): [] intel_pipe_update_start+0x113/0x5c0 [i915] [ 169.127936] softirqs last enabled at (665470): [] __do_softirq+0x236/0x650 [ 169.127942] softirqs last disabled at (665465): [] irq_exit+0xc5/0xd0 [ 169.127951] CPU: 1 PID: 1947 Comm: kms_flip Not tainted 4.1.0-rc4-patser+ #4039 [ 169.127954] Hardware name: LENOVO 2349AV8/2349AV8, BIOS G1ETA5WW (2.65 ) 04/15/2014 [ 169.127957] ffff8800c49036f0 ffff8800cde5fa28 ffffffff817f6907 0000000080000001 [ 169.127964] 0000000000000000 ffff8800cde5fa58 ffffffff810aebed 0000000000000046 [ 169.127970] ffffffff81c5d518 0000000000000268 0000000000000000 ffff8800cde5fa88 [ 169.127981] Call Trace: [ 169.127992] [] dump_stack+0x4f/0x7b [ 169.128001] [] ___might_sleep+0x16d/0x270 [ 169.128008] [] __might_sleep+0x48/0x90 [ 169.128017] [] mutex_lock_nested+0x29/0x410 [ 169.128073] [] ? vgpu_write64+0x220/0x220 [i915] [ 169.128138] [] ? ironlake_update_primary_plane+0x2ff/0x410 [i915] [ 169.128198] [] intel_frontbuffer_flush+0x25/0x70 [i915] [ 169.128253] [] intel_finish_crtc_commit+0x4c/0x180 [i915] [ 169.128279] [] drm_atomic_helper_commit_planes+0x12c/0x240 [drm_kms_helper] [ 169.128338] [] __intel_set_mode+0x684/0x830 [i915] [ 169.128378] [] intel_crtc_set_config+0x49a/0x620 [i915] [ 169.128385] [] ? mutex_unlock+0x9/0x10 [ 169.128391] [] drm_mode_set_config_internal+0x69/0x120 [ 169.128398] [] ? might_fault+0x57/0xb0 [ 169.128403] [] drm_mode_setcrtc+0x253/0x620 [ 169.128409] [] drm_ioctl+0x1a0/0x6a0 [ 169.128415] [] ? get_parent_ip+0x11/0x50 [ 169.128424] [] do_vfs_ioctl+0x2f8/0x530 [ 169.128429] [] ? trace_hardirqs_on+0xd/0x10 [ 169.128435] [] ? selinux_file_ioctl+0x56/0x100 [ 169.128439] [] SyS_ioctl+0x81/0xa0 [ 169.128445] [] system_call_fastpath+0x12/0x6f Solve it by using the newly introduced drm_atomic_helper_commit_planes_on_crtc. The problem here was that the drm_atomic_helper_commit_planes() helper we were using was basically designed to do begin_crtc_commit(crtc #1) begin_crtc_commit(crtc #2) ... commit all planes finish_crtc_commit(crtc #1) finish_crtc_commit(crtc #2) The problem here is that since our hardware relies on vblank evasion, our CRTC 'begin' function waits until we're out of the danger zone in which register writes might wind up straddling the vblank, then disables interrupts; our 'finish' function re-enables interrupts after the registers have been written. The expectation is that the operations between 'begin' and 'end' must be performed without sleeping (since interrupts are disabled) and should happen as quickly as possible. By clumping all of the 'begin' calls together, we introducing a couple problems: * Subsequent 'begin' invocations might sleep (which is illegal) * The first 'begin' ensured that we were far enough from the vblank that we could write our registers safely and ensure they all fell within the same frame. Adding extra delay waiting for subsequent CRTC's wasn't accounted for and could put us back into the 'danger zone' for CRTC #1. This commit solves the problem by using a new helper that allows an order of operations like: for each crtc { begin_crtc_commit(crtc) // sleep (maybe), then disable interrupts commit planes for this specific CRTC end_crtc_commit(crtc) // reenable interrupts } so that sleeps will only be performed while interrupts are enabled and we can be sure that registers for a CRTC will be written immediately once we know we're in the safe zone. The crtc->config->base.crtc update may seem unrelated, but the helper will use it to obtain the crtc for the state. Without the update it will dereference NULL and crash. Changes since v1: - Use Matt Roper's commit message. Signed-off-by: Maarten Lankhorst Reviewed-by: Matt Roper References: https://bugs.freedesktop.org/show_bug.cgi?id=90398 Reviewed-by: Ander Conselvan de Oliveira Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/intel_atomic.c | 45 +++++----------------------- drivers/gpu/drm/i915/intel_display.c | 11 +++---- 2 files changed, 14 insertions(+), 42 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_atomic.c b/drivers/gpu/drm/i915/intel_atomic.c index 7ed8033aae60..8e35e0d013df 100644 --- a/drivers/gpu/drm/i915/intel_atomic.c +++ b/drivers/gpu/drm/i915/intel_atomic.c @@ -129,8 +129,9 @@ int intel_atomic_commit(struct drm_device *dev, struct drm_atomic_state *state, bool async) { - int ret; - int i; + struct drm_crtc_state *crtc_state; + struct drm_crtc *crtc; + int ret, i; if (async) { DRM_DEBUG_KMS("i915 does not yet support async commit\n"); @@ -142,48 +143,18 @@ int intel_atomic_commit(struct drm_device *dev, return ret; /* Point of no return */ - - /* - * FIXME: The proper sequence here will eventually be: - * - * drm_atomic_helper_swap_state(dev, state) - * drm_atomic_helper_commit_modeset_disables(dev, state); - * drm_atomic_helper_commit_planes(dev, state); - * drm_atomic_helper_commit_modeset_enables(dev, state); - * drm_atomic_helper_wait_for_vblanks(dev, state); - * drm_atomic_helper_cleanup_planes(dev, state); - * drm_atomic_state_free(state); - * - * once we have full atomic modeset. For now, just manually update - * plane states to avoid clobbering good states with dummy states - * while nuclear pageflipping. - */ - for (i = 0; i < dev->mode_config.num_total_plane; i++) { - struct drm_plane *plane = state->planes[i]; - - if (!plane) - continue; - - plane->state->state = state; - swap(state->plane_states[i], plane->state); - plane->state->state = NULL; - } + drm_atomic_helper_swap_state(dev, state); /* swap crtc_scaler_state */ - for (i = 0; i < dev->mode_config.num_crtc; i++) { - struct drm_crtc *crtc = state->crtcs[i]; - if (!crtc) { - continue; - } - - to_intel_crtc(crtc)->config->scaler_state = - to_intel_crtc_state(state->crtc_states[i])->scaler_state; + for_each_crtc_in_state(state, crtc, crtc_state, i) { + to_intel_crtc(crtc)->config = to_intel_crtc_state(crtc->state); if (INTEL_INFO(dev)->gen >= 9) skl_detach_scalers(to_intel_crtc(crtc)); + + drm_atomic_helper_commit_planes_on_crtc(crtc_state); } - drm_atomic_helper_commit_planes(dev, state); drm_atomic_helper_wait_for_vblanks(dev, state); drm_atomic_helper_cleanup_planes(dev, state); drm_atomic_state_free(state); diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index faf4d186caf7..87476ff181dd 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -12626,17 +12626,17 @@ static int __intel_set_mode(struct drm_crtc *modeset_crtc, modeset_update_crtc_power_domains(state); - drm_atomic_helper_commit_planes(dev, state); - /* Now enable the clocks, plane, pipe, and connectors that we set up. */ for_each_crtc_in_state(state, crtc, crtc_state, i) { - if (!needs_modeset(crtc->state) || !crtc->state->enable) + if (!needs_modeset(crtc->state) || !crtc->state->enable) { + drm_atomic_helper_commit_planes_on_crtc(crtc_state); continue; + } update_scanline_offset(to_intel_crtc(crtc)); dev_priv->display.crtc_enable(crtc); - intel_crtc_enable_planes(crtc); + drm_atomic_helper_commit_planes_on_crtc(crtc_state); } /* FIXME: add subpixel order */ @@ -13269,7 +13269,7 @@ intel_check_primary_plane(struct drm_plane *plane, if (IS_BROADWELL(dev)) intel_crtc->atomic.wait_vblank = true; - if (crtc_state && !needs_modeset(&crtc_state->base)) + if (crtc_state) intel_crtc->atomic.post_enable_primary = true; } @@ -15004,6 +15004,7 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev) struct intel_plane_state *plane_state; memset(crtc->config, 0, sizeof(*crtc->config)); + crtc->config->base.crtc = &crtc->base; crtc->config->quirks |= PIPE_CONFIG_QUIRK_INHERITED_MODE; -- 2.39.2