Re: vlv_disable_backlight causing warnings with i915 @ Xorg start

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, May 08, 2017 at 09:27:36AM -0400, Andrew Siplas wrote:
> At Xorg startup after a fresh compile of the mainline kernel, WARN_ON is
> truthy and throws a warning into the kernel's dmesg buffer.
> 
> I'm still trying to understand the driver, but it originates here:
> 
> --
> 
> static void vlv_disable_backlight(struct intel_connector *connector)
> {
>         struct drm_i915_private *dev_priv =
> to_i915(connector->base.dev);
>         enum pipe pipe = intel_get_pipe_from_connector(connector);

Not sure why that's not working anymore. Did we stop updating the legacy
connector<->crtc linkage or something?

Anyway we would need to eliminate that guy and instead pass down the
correct atomic state from higher up. Maarten, did you have patches
for that already?

>         u32 tmp;
> 
>         if (WARN_ON(pipe != PIPE_A && pipe != PIPE_B))
>                 return;
> 
>         intel_panel_actually_set_backlight(connector, 0);
> 
>         tmp = I915_READ(VLV_BLC_PWM_CTL2(pipe));
>         I915_WRITE(VLV_BLC_PWM_CTL2(pipe), tmp & ~BLM_PWM_ENABLE);
> }
> 
> --
> 
> Don't know yet what this means and so taking a chance this warning is
> something someone here might have some insight into / want to know about
> especially given the "...----[ cut here ]----...".
> 
> The last two lines are from 5+ minutes after the warning but seem related:
> 
> 
> [   67.896233] ------------[ cut here ]------------
> [   67.896259] WARNING: CPU: 1 PID: 4276 at drivers/gpu/drm/i915/intel_panel.c:771 vlv_disable_backlight+0x86/0x90
> [   67.896261] Modules linked in: iptable_nat nf_nat_ipv4 nf_nat uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_core videodev
> [   67.896299] CPU: 1 PID: 4276 Comm: Xorg Not tainted 4.11.0+ #2
> [   67.896303] Hardware name: HP HP Notebook/80C5, BIOS F.1E 12/25/2015
> [   67.896308] task: ffff8d6e75d79800 task.stack: ffff9a06c1218000
> [   67.896318] RIP: 0010:vlv_disable_backlight+0x86/0x90
> [   67.896323] RSP: 0018:ffff9a06c121b998 EFLAGS: 00010286
> [   67.896330] RAX: 0000000000000029 RBX: ffff8d6e76018000 RCX: ffffffff8ea56a78
> [   67.896335] RDX: 0000000000000001 RSI: 0000000000000092 RDI: ffffffff8ece6bcc
> [   67.896339] RBP: ffff9a06c121b9b0 R08: 0000000000000029 R09: 00000000000002d8
> [   67.896344] R10: 0000000000000000 R11: 0000000000000320 R12: ffff8d6e723c5000
> [   67.896348] R13: 00000000ffffffff R14: ffff8d6e7423e800 R15: ffff8d6e74ab9830
> [   67.896355] FS:  00007fb8d7e00a40(0000) GS:ffff8d6e7fc80000(0000) knlGS:0000000000000000
> [   67.896359] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   67.896364] CR2: 0000557bfe77dfd0 CR3: 0000000274d31000 CR4: 00000000001006e0
> [   67.896368] Call Trace:
> [   67.896383]  intel_panel_disable_backlight+0x51/0x80
> [   67.896391]  intel_edp_backlight_off+0x42/0x50
> [   67.896397]  intel_disable_dp+0x70/0xf0
> [   67.896407]  intel_encoders_disable.isra.103+0x82/0x90
> [   67.896416]  i9xx_crtc_disable+0x51/0x3b0
> [   67.896424]  ? intel_crtc_disable_planes+0xd4/0xf0
> [   67.896434]  intel_atomic_commit_tail+0x892/0xfb0
> [   67.896444]  ? insert_work+0x52/0x70
> [   67.896453]  ? __queue_work+0x12e/0x390
> [   67.896461]  ? intel_atomic_commit_ready+0x70/0x80
> [   67.896470]  intel_atomic_commit+0x3e6/0x4b0
> [   67.896479]  ? handle_conflicting_encoders+0x279/0x290
> [   67.896489]  drm_atomic_commit+0x46/0x50
> [   67.896497]  drm_atomic_helper_set_config+0x6b/0xa0
> [   67.896507]  __drm_mode_set_config_internal+0x62/0x110
> [   67.896514]  drm_mode_setcrtc+0x4ba/0x5a0
> [   67.896524]  drm_ioctl+0x326/0x430
> [   67.896532]  ? drm_mode_getcrtc+0x170/0x170
> [   67.896543]  do_vfs_ioctl+0x8f/0x5a0
> [   67.896552]  ? getnstimeofday64+0x9/0x20
> [   67.896561]  SyS_ioctl+0x74/0x80
> [   67.896569]  do_syscall_64+0x48/0xb0
> [   67.896580]  entry_SYSCALL64_slow_path+0x25/0x25
> [   67.896586] RIP: 0033:0x7fb8d5932507
> [   67.896590] RSP: 002b:00007ffe8bf43018 EFLAGS: 00003246 ORIG_RAX: 0000000000000010
> [   67.896598] RAX: ffffffffffffffda RBX: 0000561b92c11210 RCX: 00007fb8d5932507
> [   67.896602] RDX: 00007ffe8bf43140 RSI: 00000000c06864a2 RDI: 0000000000000009
> [   67.896607] RBP: 00007ffe8bf43140 R08: 0000561b92c11050 R09: 0000000000000001
> [   67.896611] R10: 0000000000000001 R11: 0000000000003246 R12: 00000000c06864a2
> [   67.896615] R13: 0000000000000009 R14: 0000561b92c13f70 R15: 00007fb8d7d67000
> [   67.896620] Code: df 41 8d b4 05 50 12 06 00 ff 93 f8 06 00 00 5b 41 5c 41 5d 5d c3 48 c7 c6 18 bc 88 8e 48 c7 c7 22 e8 82 8e 31 c0 e8 47 70 b6 ff <0f> ff eb e0 66 0f 1f 44 00 00 55 8b b7 f4 03 00 00 48 89 e5 e8 
> [   67.896771] ---[ end trace 528f42628325fc1b ]---
> [  490.370803] [drm] Atomic update on pipe (A) took 102 us, max time under evasion is 100 us
> [ 2623.216311] [drm] Atomic update on pipe (A) took 415 us, max time under evasion is 100 us
> 



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-- 
Ville Syrjälä
Intel OTC
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