Acked-by: Hugues Fruchet <hugues.fruchet@xxxxxx>
On 5/27/20 5:16 PM, Benjamin Gaignard wrote:
> 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 <benjamin.gaignard@xxxxxx>
> ---
> 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);
>
