From 5ac1c4bcf073ad897c4510931518275d9e393dc7 Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst Date: Mon, 1 Jun 2015 12:50:01 +0200 Subject: [PATCH] drm/i915: Swap planes on each crtc separately, v2. 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 Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/intel_atomic.c | 13 +++---------- drivers/gpu/drm/i915/intel_display.c | 5 +++-- 2 files changed, 6 insertions(+), 12 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_atomic.c b/drivers/gpu/drm/i915/intel_atomic.c index d0b901ddb357..4df6d2d7a9c8 100644 --- a/drivers/gpu/drm/i915/intel_atomic.c +++ b/drivers/gpu/drm/i915/intel_atomic.c @@ -151,18 +151,11 @@ int intel_atomic_commit(struct drm_device *dev, if (INTEL_INFO(dev)->gen >= 9) skl_detach_scalers(to_intel_crtc(crtc)); + + drm_atomic_helper_commit_planes_on_crtc(crtc_state); } - /* - * FIXME: The proper sequence here will eventually be: - * - * drm_atomic_helper_commit_modeset_disables(dev, state); - * drm_atomic_helper_commit_planes(dev, state); - * drm_atomic_helper_commit_modeset_enables(dev, state); - * - * once we have full atomic modeset. - */ - drm_atomic_helper_commit_planes(dev, state); + /* FIXME: This function should eventually call __intel_set_mode when needed */ drm_atomic_helper_wait_for_vblanks(dev, state); drm_atomic_helper_cleanup_planes(dev, state); diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index aec398cd2289..b56641b6de70 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -12902,10 +12902,10 @@ static int __intel_set_mode(struct drm_atomic_state *state) 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) { + drm_atomic_helper_commit_planes_on_crtc(crtc_state); + if (!needs_modeset(crtc->state) || !crtc->state->active) continue; @@ -15267,6 +15267,7 @@ 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;