On Sat, 01 Feb 2020, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> If the display is not driving any pipes, we cannot change the bclk and
> doing so risks chasing NULL pointers:
Does this mean we can't probe hda if there are no displays attached at
boot on GLK?
BR,
Jani.
>
> <6> [278.907105] snd_hda_intel 0000:00:0e.0: DSP detected with PCI class/subclass/prog-if info 0x040100
> <6> [278.909936] snd_hda_intel 0000:00:0e.0: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])
> <7> [278.910078] i915 0000:00:02.0: [drm:intel_power_well_enable [i915]] enabling power well 2
> <1> [278.910228] BUG: kernel NULL pointer dereference, address: 0000000000000080
> <1> [278.910243] #PF: supervisor read access in kernel mode
> <1> [278.910251] #PF: error_code(0x0000) - not-present page
> <6> [278.910260] PGD 0 P4D 0
> <4> [278.910267] Oops: 0000 [#1] PREEMPT SMP PTI
> <4> [278.910276] CPU: 0 PID: 5 Comm: kworker/0:0 Tainted: G U 5.5.0-CI-CI_DRM_7853+ #1
> <4> [278.910289] Hardware name: Intel Corp. Geminilake/GLK RVP2 LP4SD (07), BIOS GELKRVPA.X64.0062.B30.1708222146 08/22/2017
> <4> [278.910312] Workqueue: events azx_probe_work [snd_hda_intel]
> <4> [278.910327] RIP: 0010:__ww_mutex_lock.constprop.15+0x5e/0x1090
> <4> [278.910338] Code: 75 88 be a7 03 00 00 65 48 8b 04 25 28 00 00 00 48 89 45 c8 31 c0 4c 89 c3 e8 5e b3 6d ff 44 8b 3d 2f 24 37 02 45 85 ff 75 0a <4d> 3b 6d 58 0f 85 3f 07 00 00 48 85 db 74 22 49 8b 95 80 00 00 00
> <4> [278.910362] RSP: 0018:ffffc9000008bc10 EFLAGS: 00010246
> <4> [278.910371] RAX: 0000000000000246 RBX: ffffc9000008bd30 RCX: 0000000000000001
> <4> [278.910382] RDX: 0000000000000000 RSI: ffffffff82647c60 RDI: ffff88817b27d848
> <4> [278.910393] RBP: ffffc9000008bcc0 R08: 0000000000000000 R09: 0000000000000001
> <4> [278.910404] R10: ffffc9000008bce0 R11: 0000000000000000 R12: ffffffff8168f0fc
> <4> [278.910414] R13: 0000000000000028 R14: ffffc9000008bd60 R15: 0000000000000000
> <4> [278.910425] FS: 0000000000000000(0000) GS:ffff88817bc00000(0000) knlGS:0000000000000000
> <4> [278.910437] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> <4> [278.910446] CR2: 0000000000000080 CR3: 00000001650da000 CR4: 0000000000340ef0
> <4> [278.910456] Call Trace:
> <4> [278.910468] ? mark_held_locks+0x49/0x70
> <4> [278.910479] ? ww_mutex_lock+0x39/0x70
> <4> [278.910487] ww_mutex_lock+0x39/0x70
> <4> [278.910497] drm_modeset_lock+0x6c/0x120
> <4> [278.910575] glk_force_audio_cdclk+0x7d/0x140 [i915]
> <4> [278.910656] i915_audio_component_get_power+0xf2/0x110 [i915]
> <4> [278.910673] snd_hdac_display_power+0x7d/0x120 [snd_hda_core]
> <4> [278.910686] azx_probe_work+0x88/0x7e0 [snd_hda_intel]
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_audio.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c
> index e3efd81c5855..3d92849811e1 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.c
> +++ b/drivers/gpu/drm/i915/display/intel_audio.c
> @@ -810,16 +810,14 @@ void intel_init_audio_hooks(struct drm_i915_private *dev_priv)
> }
> }
>
> -static int glk_force_audio_cdclk_commit(struct intel_atomic_state *state,
> +static int glk_force_audio_cdclk_commit(struct intel_crtc *crtc,
> + struct intel_atomic_state *state,
> bool enable)
> {
> - struct drm_i915_private *dev_priv = to_i915(state->base.dev);
> struct intel_cdclk_state *cdclk_state;
> - struct intel_crtc *crtc;
> int ret;
>
> /* need to hold at least one crtc lock for the global state */
> - crtc = intel_get_crtc_for_pipe(dev_priv, PIPE_A);
> ret = drm_modeset_lock(&crtc->base.mutex, state->base.acquire_ctx);
> if (ret)
> return ret;
> @@ -843,8 +841,13 @@ static void glk_force_audio_cdclk(struct drm_i915_private *dev_priv,
> {
> struct drm_modeset_acquire_ctx ctx;
> struct drm_atomic_state *state;
> + struct intel_crtc *crtc;
> int ret;
>
> + crtc = intel_get_crtc_for_pipe(dev_priv, PIPE_A);
> + if (!crtc)
> + return;
> +
> drm_modeset_acquire_init(&ctx, 0);
> state = drm_atomic_state_alloc(&dev_priv->drm);
> if (WARN_ON(!state))
> @@ -853,7 +856,9 @@ static void glk_force_audio_cdclk(struct drm_i915_private *dev_priv,
> state->acquire_ctx = &ctx;
>
> retry:
> - ret = glk_force_audio_cdclk_commit(to_intel_atomic_state(state), enable);
> + ret = glk_force_audio_cdclk_commit(crtc,
> + to_intel_atomic_state(state),
> + enable);
> if (ret == -EDEADLK) {
> drm_atomic_state_clear(state);
> drm_modeset_backoff(&ctx);
--
Jani Nikula, Intel Open Source Graphics Center
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