[PATCH v2 3/4] drm/atomic: Add drm_atomic_state->duplicated

[Lyude Paul <lyude@redhat.com>]

Since

commit 39b50c603878 ("drm/atomic_helper: Stop modesets on unregistered
connectors harder")

We've been failing atomic checks if they try to enable new displays on
unregistered connectors. This is fine except for the one situation that
breaks atomic assumptions: suspend/resume. If a connector is
unregistered before we attempt to restore the atomic state, something we
end up failing the atomic check that happens when trying to restore the
state during resume.

Normally this would be OK: we try our best to make sure that the atomic
state pre-suspend can be restored post-suspend, but failures at that
point usually don't cause problems. That is of course, until we
introduced the new atomic MST VCPI helpers:

[drm:drm_atomic_helper_check_modeset [drm_kms_helper]] [CRTC:65:pipe B] active changed
[drm:drm_atomic_helper_check_modeset [drm_kms_helper]] Updating routing for [CONNECTOR:123:DP-5]
[drm:drm_atomic_helper_check_modeset [drm_kms_helper]] Disabling [CONNECTOR:123:DP-5]
[drm:drm_atomic_get_private_obj_state [drm]] Added new private object 0000000025844636 state 000000009fd2899a to 000000003a13d7b8
WARNING: CPU: 6 PID: 1070 at drivers/gpu/drm/drm_dp_mst_topology.c:3153 drm_dp_atomic_release_vcpi_slots+0xb9/0x200 [drm_kms_helper]
Modules linked in: fuse vfat fat snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic joydev iTCO_wdt i915(O) wmi_bmof intel_rapl btusb btrtl x86_pkg_temp_thermal btbcm btintel coretemp i2c_algo_bit drm_kms_helper(O) crc32_pclmul snd_hda_intel syscopyarea sysfillrect snd_hda_codec sysimgblt snd_hda_core bluetooth fb_sys_fops snd_pcm pcspkr drm(O) psmouse snd_timer mei_me ecdh_generic i2c_i801 mei i2c_core ucsi_acpi typec_ucsi typec wmi thinkpad_acpi ledtrig_audio snd soundcore tpm_tis rfkill tpm_tis_core video tpm acpi_pad pcc_cpufreq uas usb_storage crc32c_intel nvme serio_raw xhci_pci nvme_core xhci_hcd
CPU: 6 PID: 1070 Comm: gnome-shell Tainted: G        W  O      5.0.0-rc2Lyude-Test+ #1
Hardware name: LENOVO 20L8S2N800/20L8S2N800, BIOS N22ET35W (1.12 ) 04/09/2018
RIP: 0010:drm_dp_atomic_release_vcpi_slots+0xb9/0x200 [drm_kms_helper]
Code: 00 4c 39 6d f0 74 49 48 8d 7b 10 48 89 f9 48 c1 e9 03 42 80 3c 21 00 0f 85 d2 00 00 00 48 8b 6b 10 48 8d 5d f0 49 39 ee 75 c5 <0f> 0b 48 c7 c7 c0 78 b3 a0 48 89 c2 4c 89 ee e8 03 6c aa ff b8 ea
RSP: 0018:ffff88841235f268 EFLAGS: 00010246
RAX: ffff88841bf12ab0 RBX: ffff88841bf12aa8 RCX: 1ffff110837e2557
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffed108246bde0
RBP: ffff88841bf12ab8 R08: ffffed1083db3c93 R09: ffffed1083db3c92
R10: ffffed1083db3c92 R11: ffff88841ed9e497 R12: ffff888419555d80
R13: ffff8883bc499100 R14: ffff88841bf12ab8 R15: 0000000000000000
FS:  00007f16fbd4cd00(0000) GS:ffff88841ed80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1687c9f000 CR3: 00000003ba3cc003 CR4: 00000000003606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 drm_atomic_helper_check_modeset+0xf21/0x2f50 [drm_kms_helper]
 ? drm_atomic_helper_commit_modeset_enables+0xa90/0xa90 [drm_kms_helper]
 ? __printk_safe_exit+0x10/0x10
 ? save_stack+0x8c/0xb0
 ? vprintk_func+0x96/0x1bf
 ? __printk_safe_exit+0x10/0x10
 intel_atomic_check+0x234/0x4750 [i915]
 ? printk+0x9f/0xc5
 ? kmsg_dump_rewind_nolock+0xd9/0xd9
 ? _raw_spin_lock_irqsave+0xa4/0x140
 ? drm_atomic_check_only+0xb1/0x28b0 [drm]
 ? drm_dbg+0x186/0x1b0 [drm]
 ? drm_dev_dbg+0x200/0x200 [drm]
 ? intel_link_compute_m_n+0xb0/0xb0 [i915]
 ? drm_mode_put_tile_group+0x20/0x20 [drm]
 ? skl_plane_format_mod_supported+0x17f/0x1b0 [i915]
 ? drm_plane_check_pixel_format+0x14a/0x310 [drm]
 drm_atomic_check_only+0x13c4/0x28b0 [drm]
 ? drm_state_info+0x220/0x220 [drm]
 ? drm_atomic_helper_disable_plane+0x1d0/0x1d0 [drm_kms_helper]
 ? pick_single_encoder_for_connector+0xe0/0xe0 [drm_kms_helper]
 ? kasan_unpoison_shadow+0x35/0x40
 drm_atomic_commit+0x3b/0x100 [drm]
 drm_atomic_helper_set_config+0xd5/0x100 [drm_kms_helper]
 drm_mode_setcrtc+0x636/0x1660 [drm]
 ? vprintk_func+0x96/0x1bf
 ? drm_dev_dbg+0x200/0x200 [drm]
 ? drm_mode_getcrtc+0x790/0x790 [drm]
 ? printk+0x9f/0xc5
 ? mutex_unlock+0x1d/0x40
 ? drm_mode_addfb2+0x2e9/0x3a0 [drm]
 ? rcu_sync_dtor+0x2e0/0x2e0
 ? drm_dbg+0x186/0x1b0 [drm]
 ? set_page_dirty+0x271/0x4d0
 drm_ioctl_kernel+0x203/0x290 [drm]
 ? drm_mode_getcrtc+0x790/0x790 [drm]
 ? drm_setversion+0x7f0/0x7f0 [drm]
 ? __switch_to_asm+0x34/0x70
 ? __switch_to_asm+0x34/0x70
 drm_ioctl+0x445/0x950 [drm]
 ? drm_mode_getcrtc+0x790/0x790 [drm]
 ? drm_getunique+0x220/0x220 [drm]
 ? expand_files.part.10+0x920/0x920
 do_vfs_ioctl+0x1a1/0x13d0
 ? ioctl_preallocate+0x2b0/0x2b0
 ? __fget_light+0x2d6/0x390
 ? schedule+0xd7/0x2e0
 ? fget_raw+0x10/0x10
 ? apic_timer_interrupt+0xa/0x20
 ? apic_timer_interrupt+0xa/0x20
 ? rcu_cleanup_dead_rnp+0x2c0/0x2c0
 ksys_ioctl+0x60/0x90
 __x64_sys_ioctl+0x6f/0xb0
 do_syscall_64+0x136/0x440
 ? syscall_return_slowpath+0x2d0/0x2d0
 ? do_page_fault+0x89/0x330
 ? __do_page_fault+0x9c0/0x9c0
 ? prepare_exit_to_usermode+0x188/0x200
 ? perf_trace_sys_enter+0x1090/0x1090
 ? __x64_sys_sigaltstack+0x280/0x280
 ? __put_user_4+0x1c/0x30
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f16ff89a09b
Code: 0f 1e fa 48 8b 05 ed bd 0c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d bd bd 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007fff001232b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fff001232f0 RCX: 00007f16ff89a09b
RDX: 00007fff001232f0 RSI: 00000000c06864a2 RDI: 000000000000000b
RBP: 00007fff001232f0 R08: 0000000000000000 R09: 000055a79d484460
R10: 000055a79d44e770 R11: 0000000000000246 R12: 00000000c06864a2
R13: 000000000000000b R14: 0000000000000000 R15: 000055a79d44e770
WARNING: CPU: 6 PID: 1070 at drivers/gpu/drm/drm_dp_mst_topology.c:3153 drm_dp_atomic_release_vcpi_slots+0xb9/0x200 [drm_kms_helper]
---[ end trace d536c05c13c83be2 ]---
[drm:drm_dp_atomic_release_vcpi_slots [drm_kms_helper]] *ERROR* no VCPI for [MST PORT:00000000f9e2b143] found in mst state 000000009fd2899a

This appears to be happening because we destroy the VCPI allocations
when disabling all connected displays while suspending, and those VCPI
allocations don't get restored on resume due to failing to restore the
atomic state.

So, fix this by introducing the suspending option to
drm_atomic_helper_duplicate_state() and use that to indicate in the
atomic state that it's being used for suspending or resuming the system,
and thus needs to be fixed up by the driver. We can then use the new
state->duplicated hook to tell update_connector_routing() in
drm_atomic_check_modeset() to allow for modesets on unregistered
connectors, which allows us to restore atomic states that contain MST
topologies that were removed after the state was duplicated and thus:
mostly fixing suspend and resume. This just leaves some issues that were
introduced with nouveau, that will be addressed next.

Changes since v2:
* Remove the changes in this patch to the VCPI helpers, they aren't
  needed anymore
Changes since v1:
* Rename suspend_or_resume to duplicated

Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: eceae1472467 ("drm/dp_mst: Start tracking per-port VCPI allocations")
Cc: Daniel Vetter <daniel@ffwll.ch>
---
 drivers/gpu/drm/drm_atomic_helper.c   | 10 +++++++++-
 drivers/gpu/drm/drm_dp_mst_topology.c | 28 +++++++++++++++++++++++++++
 include/drm/drm_atomic.h              |  9 +++++++++
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 6fe2303fccd9..f578bf1fe164 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -332,8 +332,15 @@ update_connector_routing(struct drm_atomic_state *state,
 	 * about is ensuring that userspace can't do anything but shut off the
 	 * display on a connector that was destroyed after its been notified,
 	 * not before.
+	 *
+	 * Additionally, we also want to ignore connector registration when
+	 * we're trying to restore an atomic state during system resume since
+	 * there's a chance the connector may have been destroyed during the
+	 * process, but it's better to ignore that then cause
+	 * drm_atomic_helper_resume() to fail.
 	 */
-	if (drm_connector_is_unregistered(connector) && crtc_state->active) {
+	if (!state->duplicated && drm_connector_is_unregistered(connector) &&
+	    crtc_state->active) {
 		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] is not registered\n",
 				 connector->base.id, connector->name);
 		return -EINVAL;
@@ -3180,6 +3187,7 @@ drm_atomic_helper_duplicate_state(struct drm_device *dev,
 		return ERR_PTR(-ENOMEM);
 
 	state->acquire_ctx = ctx;
+	state->duplicated = true;
 
 	drm_for_each_crtc(crtc, dev) {
 		struct drm_crtc_state *crtc_state;
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 4325e1518286..ea1540ea67af 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3097,6 +3097,10 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
  * @port as needed. It is not OK however, to call this function and
  * drm_dp_atomic_release_vcpi_slots() in the same atomic check phase.
  *
+ * When &drm_atomic_state.duplicated is set to %true%, this function will not
+ * perform any error checking and will instead simply return the previously
+ * recorded VCPI allocations.
+ *
  * See also:
  * drm_dp_atomic_release_vcpi_slots()
  * drm_dp_mst_atomic_check()
@@ -3123,6 +3127,19 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 			vcpi = pos;
 			prev_slots = vcpi->vcpi;
 
+			/*
+			 * When resuming, we just want to restore the previous
+			 * VCPI without doing error checking
+			 */
+			if (state->duplicated) {
+				DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] restoring VCPI of %d\n",
+						 port->connector->base.id,
+						 port->connector->name,
+						 port, prev_slots);
+
+				return prev_slots;
+			}
+
 			/*
 			 * This should never happen, unless the driver tries
 			 * releasing and allocating the same VCPI allocation,
@@ -3181,6 +3198,11 @@ EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
  * drm_dp_atomic_find_vcpi_slots() on the same @port in a single atomic check
  * phase.
  *
+ * When &drm_atomic_state.duplicated is set, this function will not
+ * modify the VCPI allocations in &drm_dp_mst_topology_state.vcpis, so that
+ * those VCPI allocations may be restored as-is from the duplicated state. In
+ * this scenario, this function will always return 0.
+ *
  * See also:
  * drm_dp_atomic_find_vcpi_slots()
  * drm_dp_mst_atomic_check()
@@ -3197,6 +3219,12 @@ int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 	struct drm_dp_vcpi_allocation *pos;
 	bool found = false;
 
+	/* During suspend, just keep our VCPI allocations as-is in the atomic
+	 * state so they can be restored as-is at resume
+	 */
+	if (state->duplicated)
+		return 0;
+
 	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
 	if (IS_ERR(topology_state))
 		return PTR_ERR(topology_state);
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 811b4a92568f..961c792fa98b 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -329,6 +329,15 @@ struct drm_atomic_state {
 	bool allow_modeset : 1;
 	bool legacy_cursor_update : 1;
 	bool async_update : 1;
+	/**
+	 * @duplicated:
+	 *
+	 * Indicates whether or not this atomic state was duplicated using
+	 * drm_atomic_helper_duplicate_state(). Drivers and atomic helpers
+	 * should use this to fixup normal  inconsistencies in duplicated
+	 * states.
+	 */
+	bool duplicated : 1;
 	struct __drm_planes_state *planes;
 	struct __drm_crtcs_state *crtcs;
 	int num_connector;
-- 
2.20.1