[PATCH 1/2] drm/msm/devfreq: Add some locking asserts

[PATCH 1/2] drm/msm/devfreq: Add some locking asserts

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index 47b3cf2df230..b24e5475cafb 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -20,6 +20,8 @@ static int msm_devfreq_target(struct device *dev, unsigned long *freq,
 	struct msm_gpu *gpu = dev_to_gpu(dev);
 	struct dev_pm_opp *opp;
 
+	WARN_ON(!mutex_is_locked(&gpu->devfreq.devfreq->lock));
+
 	opp = devfreq_recommended_opp(dev, freq, flags);
 
 	/*
@@ -63,6 +65,8 @@ static int msm_devfreq_get_dev_status(struct device *dev,
 	struct msm_gpu *gpu = dev_to_gpu(dev);
 	ktime_t time;
 
+	WARN_ON(!mutex_is_locked(&gpu->devfreq.devfreq->lock));
+
 	status->current_frequency = get_freq(gpu);
 	status->busy_time = gpu->funcs->gpu_busy(gpu);
 
@@ -75,7 +79,11 @@ static int msm_devfreq_get_dev_status(struct device *dev,
 
 static int msm_devfreq_get_cur_freq(struct device *dev, unsigned long *freq)
 {
-	*freq = get_freq(dev_to_gpu(dev));
+	struct msm_gpu *gpu = dev_to_gpu(dev);
+
+	WARN_ON(!mutex_is_locked(&gpu->devfreq.devfreq->lock));
+
+	*freq = get_freq(gpu);
 
 	return 0;
 }
-- 
2.31.1

[PATCH 2/2] drm/msm/gpu: Respect PM QoS constraints

[Rob Clark]

From: Rob Clark <robdclark@chromium.org>

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 31 +++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index b24e5475cafb..427c55002f4d 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -158,6 +158,33 @@ void msm_devfreq_suspend(struct msm_gpu *gpu)
 	devfreq_suspend_device(gpu->devfreq.devfreq);
 }
 
+static void set_target(struct msm_gpu *gpu, unsigned long freq)
+{
+	struct msm_gpu_devfreq *df = &gpu->devfreq;
+	unsigned long min_freq, max_freq;
+	u32 flags = 0;
+
+	/*
+	 * When setting the target freq internally, we need to apply PM QoS
+	 * constraints (such as cooling):
+	 */
+	min_freq = dev_pm_qos_read_value(df->devfreq->dev.parent,
+					 DEV_PM_QOS_MIN_FREQUENCY);
+	max_freq = dev_pm_qos_read_value(df->devfreq->dev.parent,
+					 DEV_PM_QOS_MAX_FREQUENCY);
+
+	if (freq < min_freq) {
+		freq = min_freq;
+		flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
+	}
+	if (freq > max_freq) {
+		freq = max_freq;
+		flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
+	}
+
+	msm_devfreq_target(&gpu->pdev->dev, &freq, flags);
+}
+
 void msm_devfreq_boost(struct msm_gpu *gpu, unsigned factor)
 {
 	struct msm_gpu_devfreq *df = &gpu->devfreq;
@@ -173,7 +200,7 @@ void msm_devfreq_boost(struct msm_gpu *gpu, unsigned factor)
 
 	freq *= factor;
 
-	msm_devfreq_target(&gpu->pdev->dev, &freq, 0);
+	set_target(gpu, freq);
 
 	mutex_unlock(&df->devfreq->lock);
 }
@@ -212,7 +239,7 @@ void msm_devfreq_active(struct msm_gpu *gpu)
 
 	df->idle_freq = 0;
 
-	msm_devfreq_target(&gpu->pdev->dev, &target_freq, 0);
+	set_target(gpu, target_freq);
 
 	/*
 	 * Reset the polling interval so we aren't inconsistent
-- 
2.31.1

Re: [PATCH 2/2] drm/msm/gpu: Respect PM QoS constraints

[Doug Anderson]

Hi,

On Wed, Nov 3, 2021 at 1:59 PM Rob Clark <robdclark@gmail.com> wrote:
>
> From: Rob Clark <robdclark@chromium.org>
>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>  drivers/gpu/drm/msm/msm_gpu_devfreq.c | 31 +++++++++++++++++++++++++--
>  1 file changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> index b24e5475cafb..427c55002f4d 100644
> --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> @@ -158,6 +158,33 @@ void msm_devfreq_suspend(struct msm_gpu *gpu)
>         devfreq_suspend_device(gpu->devfreq.devfreq);
>  }
>
> +static void set_target(struct msm_gpu *gpu, unsigned long freq)
> +{
> +       struct msm_gpu_devfreq *df = &gpu->devfreq;
> +       unsigned long min_freq, max_freq;
> +       u32 flags = 0;
> +
> +       /*
> +        * When setting the target freq internally, we need to apply PM QoS
> +        * constraints (such as cooling):
> +        */
> +       min_freq = dev_pm_qos_read_value(df->devfreq->dev.parent,
> +                                        DEV_PM_QOS_MIN_FREQUENCY);

Chatted with Rob offline about this, but to document on the lists for
those playing at home: the above function isn't exported to modules,
so this will fail with "allmodconfig".

In general this isn't the right approach here. I believe that the
right approach is to boost with freq_qos_update_request() and then
kick off a timer to stop boosting after a fixed period of time.


-Doug