On Wed, Aug 02, 2023 at 04:35:01PM -0700, Alan Previn wrote:
> When suspending, add a timeout when calling
> intel_gt_pm_wait_for_idle else if we have a lost
> G2H event that holds a wakeref (which would be
> indicating of a bug elsewhere in the driver), we
> get to complete the suspend-resume cycle, albeit
> without all the lower power hw counters hitting
> its targets, instead of hanging in the kernel.
>
> Signed-off-by: Alan Previn <alan.previn.teres.alexis@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 +-
> drivers/gpu/drm/i915/gt/intel_gt_pm.c | 7 ++++++-
> drivers/gpu/drm/i915/gt/intel_gt_pm.h | 7 ++++++-
> drivers/gpu/drm/i915/intel_wakeref.c | 14 ++++++++++----
> drivers/gpu/drm/i915/intel_wakeref.h | 5 +++--
> 5 files changed, 26 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index ee15486fed0d..090438eb8682 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> @@ -688,7 +688,7 @@ void intel_engines_release(struct intel_gt *gt)
> if (!engine->release)
> continue;
>
> - intel_wakeref_wait_for_idle(&engine->wakeref);
> + intel_wakeref_wait_for_idle(&engine->wakeref, 0);
> GEM_BUG_ON(intel_engine_pm_is_awake(engine));
>
> engine->release(engine);
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> index 3162d859ed68..dfe77eb3efd1 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
> @@ -289,6 +289,8 @@ int intel_gt_resume(struct intel_gt *gt)
>
> static void wait_for_suspend(struct intel_gt *gt)
> {
> + int timeout_ms = CONFIG_DRM_I915_MAX_REQUEST_BUSYWAIT ? : 10000;
> +
> if (!intel_gt_pm_is_awake(gt)) {
> intel_uc_suspend_prepare(>->uc);
> return;
> @@ -305,7 +307,10 @@ static void wait_for_suspend(struct intel_gt *gt)
> intel_uc_suspend_prepare(>->uc);
> }
>
> - intel_gt_pm_wait_for_idle(gt);
> + /* we are suspending, so we shouldn't be waiting forever */
> + if (intel_gt_pm_wait_timeout_for_idle(gt, timeout_ms) == -ETIME)
> + drm_warn(>->i915->drm, "Bailing from %s after %d milisec timeout\n",
> + __func__, timeout_ms);
> }
>
> void intel_gt_suspend_prepare(struct intel_gt *gt)
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> index 6c9a46452364..5358acc2b5b1 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> @@ -68,7 +68,12 @@ static inline void intel_gt_pm_might_put(struct intel_gt *gt)
>
> static inline int intel_gt_pm_wait_for_idle(struct intel_gt *gt)
> {
> - return intel_wakeref_wait_for_idle(>->wakeref);
> + return intel_wakeref_wait_for_idle(>->wakeref, 0);
> +}
> +
> +static inline int intel_gt_pm_wait_timeout_for_idle(struct intel_gt *gt, int timeout_ms)
> +{
> + return intel_wakeref_wait_for_idle(>->wakeref, timeout_ms);
> }
>
> void intel_gt_pm_init_early(struct intel_gt *gt);
> diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
> index 718f2f1b6174..7e01d4cc300c 100644
> --- a/drivers/gpu/drm/i915/intel_wakeref.c
> +++ b/drivers/gpu/drm/i915/intel_wakeref.c
> @@ -111,14 +111,20 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
> "wakeref.work", &key->work, 0);
> }
>
> -int intel_wakeref_wait_for_idle(struct intel_wakeref *wf)
> +int intel_wakeref_wait_for_idle(struct intel_wakeref *wf, int timeout_ms)
> {
> - int err;
> + int err = 0;
>
> might_sleep();
>
> - err = wait_var_event_killable(&wf->wakeref,
> - !intel_wakeref_is_active(wf));
> + if (!timeout_ms)
> + err = wait_var_event_killable(&wf->wakeref,
> + !intel_wakeref_is_active(wf));
> + else if (wait_var_event_timeout(&wf->wakeref,
> + !intel_wakeref_is_active(wf),
> + msecs_to_jiffies(timeout_ms)) < 1)
> + err = -ETIME;
it looks to me that -ETIMEDOUT would be a better error.
> +
> if (err)
> return err;
>
> diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
> index ec881b097368..6fbb7a2fb6ea 100644
> --- a/drivers/gpu/drm/i915/intel_wakeref.h
> +++ b/drivers/gpu/drm/i915/intel_wakeref.h
> @@ -251,15 +251,16 @@ __intel_wakeref_defer_park(struct intel_wakeref *wf)
> /**
> * intel_wakeref_wait_for_idle: Wait until the wakeref is idle
> * @wf: the wakeref
> + * @timeout_ms: timeout to wait in milisecs, zero means forever
> *
> * Wait for the earlier asynchronous release of the wakeref. Note
> * this will wait for any third party as well, so make sure you only wait
> * when you have control over the wakeref and trust no one else is acquiring
> * it.
> *
> - * Return: 0 on success, error code if killed.
> + * Return: 0 on success, error code if killed, -ETIME if timed-out.
> */
> -int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
> +int intel_wakeref_wait_for_idle(struct intel_wakeref *wf, int timeout_ms);
>
> struct intel_wakeref_auto {
> struct drm_i915_private *i915;
> --
> 2.39.0
>
