Re: [PATCH v2] drm/i915: Kick the rps worker when changing the boost frequency

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> The boost frequency is only applied from the RPS worker while someone is
> waiting on a request and requested a boost. As such, when the user
> wishes to change the frequency, we have to kick the worker in order to
> re-evaluate whether to apply the boost frequency.
>
> v2: Check num_waiters to decide if we should kick the worker to handle
> boosting.
>
> Fixes: 29ecd78d3b79 ("drm/i915: Define a separate variable and control for RPS waitboost frequency")
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@intel.com>

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_sysfs.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index b33d2158c234..e5e6f6bb2b05 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -304,8 +304,9 @@ static ssize_t gt_boost_freq_mhz_store(struct device *kdev,
>  {
>  	struct drm_i915_private *dev_priv = kdev_minor_to_i915(kdev);
>  	struct intel_rps *rps = &dev_priv->gt_pm.rps;
> -	u32 val;
> +	bool boost = false;
>  	ssize_t ret;
> +	u32 val;
>  
>  	ret = kstrtou32(buf, 0, &val);
>  	if (ret)
> @@ -317,8 +318,13 @@ static ssize_t gt_boost_freq_mhz_store(struct device *kdev,
>  		return -EINVAL;
>  
>  	mutex_lock(&dev_priv->pcu_lock);
> -	rps->boost_freq = val;
> +	if (val != rps->boost_freq) {
> +		rps->boost_freq = val;
> +		boost = atomic_read(&rps->num_waiters);
> +	}
>  	mutex_unlock(&dev_priv->pcu_lock);
> +	if (boost)
> +		schedule_work(&rps->work);
>  
>  	return count;
>  }
> -- 
> 2.16.2
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