Before start streaming set cpufreq minimum frequency requirement. The cpufreq governor will adapt the frequencies and we will have no latency for handling interrupts.
Signed-off-by: Benjamin Gaignard <[email protected]> --- drivers/media/platform/stm32/stm32-dcmi.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c index b8931490b83b..97c342351569 100644 --- a/drivers/media/platform/stm32/stm32-dcmi.c +++ b/drivers/media/platform/stm32/stm32-dcmi.c @@ -13,6 +13,7 @@ #include <linux/clk.h> #include <linux/completion.h> +#include <linux/cpufreq.h> #include <linux/delay.h> #include <linux/dmaengine.h> #include <linux/init.h> @@ -99,6 +100,8 @@ enum state { #define OVERRUN_ERROR_THRESHOLD 3 +#define DCMI_MIN_FREQ 650000 /* in KHz */ + struct dcmi_graph_entity { struct v4l2_async_subdev asd; @@ -173,6 +176,10 @@ struct stm32_dcmi { struct media_device mdev; struct media_pad vid_cap_pad; struct media_pipeline pipeline; + + /* CPU freq contraint */ + struct cpufreq_policy *policy; + struct freq_qos_request qos_req; }; static inline struct stm32_dcmi *notifier_to_dcmi(struct v4l2_async_notifier *n) @@ -736,11 +743,20 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count) goto err_release_buffers; } + if (dcmi->policy) { + ret = freq_qos_add_request(&dcmi->policy->constraints, + &dcmi->qos_req, FREQ_QOS_MIN, + DCMI_MIN_FREQ); + + if (ret < 0) + goto err_pm_put; + } + ret = media_pipeline_start(&dcmi->vdev->entity, &dcmi->pipeline); if (ret < 0) { dev_err(dcmi->dev, "%s: Failed to start streaming, media pipeline start error (%d)\n", __func__, ret); - goto err_pm_put; + goto err_drop_qos; } ret = dcmi_pipeline_start(dcmi); @@ -835,6 +851,9 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count) err_media_pipeline_stop: media_pipeline_stop(&dcmi->vdev->entity); +err_drop_qos: + if (dcmi->policy) + freq_qos_remove_request(&dcmi->qos_req); err_pm_put: pm_runtime_put(dcmi->dev); @@ -863,6 +882,9 @@ static void dcmi_stop_streaming(struct vb2_queue *vq) media_pipeline_stop(&dcmi->vdev->entity); + if (dcmi->policy) + freq_qos_remove_request(&dcmi->qos_req); + spin_lock_irq(&dcmi->irqlock); /* Disable interruptions */ @@ -2020,6 +2042,8 @@ static int dcmi_probe(struct platform_device *pdev) goto err_cleanup; } + dcmi->policy = cpufreq_cpu_get(0); + dev_info(&pdev->dev, "Probe done\n"); platform_set_drvdata(pdev, dcmi); @@ -2049,6 +2073,9 @@ static int dcmi_remove(struct platform_device *pdev) pm_runtime_disable(&pdev->dev); + if (dcmi->policy) + cpufreq_cpu_put(dcmi->policy); + v4l2_async_notifier_unregister(&dcmi->notifier); v4l2_async_notifier_cleanup(&dcmi->notifier); media_entity_cleanup(&dcmi->vdev->entity); -- 2.15.0
