Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> During suspend we want to flush out all active contexts and their
> rendering. To do so we queue a request from the kernel's context, once
> we know that request is done, we know the GPU is completely idle. To
> speed up that switch bump the GPU clocks.
>
> Switching to the kernel context prior to idling is also used to enforce
> a barrier before changing OA properties, and when evicting active
> rendering from the global GTT. All cases where we do want to
> race-to-idle.
>
> v2: Limit the boosting to only the switch before suspend.
> v3: Limit it to the wait-for-idle on suspend.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: David Weinehall <david.weinehall@xxxxxxxxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> #v1
> Tested-by: David Weinehall <david.weinehall@xxxxxxxxxxxxxxx> #v1
> ---
> drivers/gpu/drm/i915/i915_gem.c | 27 +++++++++++++++++++++++++--
> drivers/gpu/drm/i915/i915_request.h | 1 +
> 2 files changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index c93f5dcb1d82..7b5544efa0ba 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3704,7 +3704,29 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
>
> static int wait_for_timeline(struct i915_timeline *tl, unsigned int flags)
> {
> - return i915_gem_active_wait(&tl->last_request, flags);
> + struct i915_request *rq;
> + long ret;
> +
> + rq = i915_gem_active_get_unlocked(&tl->last_request);
> + if (!rq)
> + return 0;
> +
> + /*
> + * "Race-to-idle".
> + *
> + * Switching to the kernel context is often used a synchronous
> + * step prior to idling, e.g. in suspend for flushing all
> + * current operations to memory before sleeping. These we
> + * want to complete as quickly as possible to avoid prolonged
> + * stalls, so allow the gpu to boost to maximum clocks.
> + */
> + if (flags & I915_WAIT_FOR_IDLE_BOOST)
> + gen6_rps_boost(rq, NULL);
> +
> + ret = i915_request_wait(rq, flags, MAX_SCHEDULE_TIMEOUT);
I pondered about the boost flag falling through into wait.
But they are flags on wait domain so no reason to split/limit.
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> + i915_request_put(rq);
> +
> + return ret < 0 ? ret : 0;
> }
>
> static int wait_for_engines(struct drm_i915_private *i915)
> @@ -4979,7 +5001,8 @@ int i915_gem_suspend(struct drm_i915_private *dev_priv)
>
> ret = i915_gem_wait_for_idle(dev_priv,
> I915_WAIT_INTERRUPTIBLE |
> - I915_WAIT_LOCKED);
> + I915_WAIT_LOCKED |
> + I915_WAIT_FOR_IDLE_BOOST);
> if (ret && ret != -EIO)
> goto err_unlock;
>
> diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
> index 1bbbb7a9fa03..491ff81d0fea 100644
> --- a/drivers/gpu/drm/i915/i915_request.h
> +++ b/drivers/gpu/drm/i915/i915_request.h
> @@ -267,6 +267,7 @@ long i915_request_wait(struct i915_request *rq,
> #define I915_WAIT_INTERRUPTIBLE BIT(0)
> #define I915_WAIT_LOCKED BIT(1) /* struct_mutex held, handle GPU reset */
> #define I915_WAIT_ALL BIT(2) /* used by i915_gem_object_wait() */
> +#define I915_WAIT_FOR_IDLE_BOOST BIT(3)
>
> static inline u32 intel_engine_get_seqno(struct intel_engine_cs *engine);
>
> --
> 2.17.0
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