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Message-ID: <b40a7312-9ea8-098f-8ba8-f080b3f57b5f@st.com>
Date: Wed, 24 Jun 2020 09:24:17 +0000
From: Hugues FRUCHET <hugues.fruchet@...com>
To: Benjamin GAIGNARD <benjamin.gaignard@...com>,
"mchehab@...nel.org" <mchehab@...nel.org>,
"mcoquelin.stm32@...il.com" <mcoquelin.stm32@...il.com>,
Alexandre TORGUE <alexandre.torgue@...com>
CC: "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
"linux-stm32@...md-mailman.stormreply.com"
<linux-stm32@...md-mailman.stormreply.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
"valentin.schneider@....com" <valentin.schneider@....com>,
"rjw@...ysocki.net" <rjw@...ysocki.net>
Subject: Re: [PATCH v6 2/3] media: stm32-dcmi: Set minimum cpufreq requirement
Hi Benjamin,
test condition in set_min_frequency() to fix, appart from that:
Acked-by: Hugues Fruchet <hugues.fruchet@...com>
BR,
Hugues.
On 6/10/20 2:24 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.
> The frequency requirement is retrieved from the device-tree node.
>
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
> ---
> version 6:
> - come back to version 4 and follow Valentin's suggestions about notifier
> - add Valentin's comment about notifier set/unset
>
> version 5:
> - add a mutex to protect dcmi_irq_notifier_notify()
> - register notifier a probe time
>
> version 4:
> - simplify irq affinity handling by using only dcmi_irq_notifier_notify()
>
> version 3:
> - add a cpumask field to track boosted CPUs
> - add irq_affinity_notify callback
> - protect cpumask field with a mutex
>
> drivers/media/platform/stm32/stm32-dcmi.c | 138 ++++++++++++++++++++++++++++--
> 1 file changed, 130 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
> index b8931490b83b..382df6e7c864 100644
> --- a/drivers/media/platform/stm32/stm32-dcmi.c
> +++ b/drivers/media/platform/stm32/stm32-dcmi.c
> @@ -13,10 +13,13 @@
>
> #include <linux/clk.h>
> #include <linux/completion.h>
> +#include <linux/cpufreq.h>
> +#include <linux/cpumask.h>
> #include <linux/delay.h>
> #include <linux/dmaengine.h>
> #include <linux/init.h>
> #include <linux/interrupt.h>
> +#include <linux/irq.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/of.h>
> @@ -99,6 +102,8 @@ enum state {
>
> #define OVERRUN_ERROR_THRESHOLD 3
>
> +static DEFINE_PER_CPU(struct freq_qos_request, qos_req);
> +
> struct dcmi_graph_entity {
> struct v4l2_async_subdev asd;
>
> @@ -133,6 +138,7 @@ struct stm32_dcmi {
> struct resource *res;
> struct reset_control *rstc;
> int sequence;
> + int irq;
> struct list_head buffers;
> struct dcmi_buf *active;
>
> @@ -173,6 +179,11 @@ struct stm32_dcmi {
> struct media_device mdev;
> struct media_pad vid_cap_pad;
> struct media_pipeline pipeline;
> +
> + struct mutex freq_lock;
> + u32 min_frequency;
> + cpumask_var_t boosted;
> + struct irq_affinity_notify notify;
> };
>
> static inline struct stm32_dcmi *notifier_to_dcmi(struct v4l2_async_notifier *n)
> @@ -722,6 +733,99 @@ static void dcmi_pipeline_stop(struct stm32_dcmi *dcmi)
> dcmi_pipeline_s_stream(dcmi, 0);
> }
>
> +static void dcmi_get_min_frequency(struct stm32_dcmi *dcmi)
> +{
> + struct device_node *np = dcmi->mdev.dev->of_node;
> +
> + dcmi->min_frequency = FREQ_QOS_MIN_DEFAULT_VALUE;
> +
> + of_property_read_u32(np, "st,stm32-dcmi-min-frequency",
> + &dcmi->min_frequency);
> +}
> +
> +static void dcmi_irq_notifier_notify(struct irq_affinity_notify *notify,
> + const cpumask_t *mask)
> +{
> + struct stm32_dcmi *dcmi = container_of(notify,
> + struct stm32_dcmi,
> + notify);
> + struct cpufreq_policy *p;
> + int cpu;
> +
> + mutex_lock(&dcmi->freq_lock);
> + /*
> + * For all boosted CPUs check if it is still the case
> + * if not remove the request
> + */
> + for_each_cpu(cpu, dcmi->boosted) {
> + if (cpumask_test_cpu(cpu, mask))
> + continue;
> +
> + p = cpufreq_cpu_get(cpu);
> + if (!p)
> + continue;
> +
> + freq_qos_remove_request(&per_cpu(qos_req, cpu));
> + cpumask_andnot(dcmi->boosted, dcmi->boosted, p->cpus);
> +
> + cpufreq_cpu_put(p);
> + }
> +
> + /*
> + * For CPUs in the mask check if they are boosted if not add
> + * a request
> + */
> + for_each_cpu(cpu, mask) {
> + if (cpumask_test_cpu(cpu, dcmi->boosted))
> + continue;
> +
> + p = cpufreq_cpu_get(cpu);
> + if (!p)
> + continue;
> +
> + freq_qos_add_request(&p->constraints, &per_cpu(qos_req, cpu),
> + FREQ_QOS_MIN, dcmi->min_frequency);
> + cpumask_or(dcmi->boosted, dcmi->boosted, p->cpus);
> + cpufreq_cpu_put(p);
> + }
> +
> + mutex_unlock(&dcmi->freq_lock);
> +}
> +
> +static void dcmi_irq_notifier_release(struct kref *ref)
> +{
> + /*
> + * This is required by affinity notifier. We don't have anything to
> + * free here.
> + */
> +}
> +
> +static void dcmi_set_min_frequency(struct stm32_dcmi *dcmi, s32 freq)
> +{
> + struct irq_affinity_notify *notify = &dcmi->notify;
> + struct cpumask clear;
> +
> + if (freq) {
if (freq != FREQ_QOS_MIN_DEFAULT_VALUE)
> + /*
> + * Register the notifier before doing any change, so the
> + * callback can be queued if an affinity change happens *while*
> + * we are requesting the boosts.
> + */
> + irq_set_affinity_notifier(dcmi->irq, notify);
> + dcmi_irq_notifier_notify(notify,
> + irq_get_affinity_mask(dcmi->irq));
> + } else {
> + /*
> + * Unregister the notifier before clearing the boost requests,
> + * as we don't want to boost again if an affinity change happens
> + * *while* we are clearing the requests
> + */
> + irq_set_affinity_notifier(dcmi->irq, NULL);
> + cpumask_clear(&clear);
> + dcmi_irq_notifier_notify(notify, &clear);
> + }
> +}
> +
> static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
> {
> struct stm32_dcmi *dcmi = vb2_get_drv_priv(vq);
> @@ -736,11 +840,13 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
> goto err_release_buffers;
> }
>
> + dcmi_set_min_frequency(dcmi, dcmi->min_frequency);
> +
> 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);
> @@ -835,7 +941,8 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
> err_media_pipeline_stop:
> media_pipeline_stop(&dcmi->vdev->entity);
>
> -err_pm_put:
> +err_drop_qos:
> + dcmi_set_min_frequency(dcmi, FREQ_QOS_MIN_DEFAULT_VALUE) > pm_runtime_put(dcmi->dev);
>
> err_release_buffers:
> @@ -863,6 +970,8 @@ static void dcmi_stop_streaming(struct vb2_queue *vq)
>
> media_pipeline_stop(&dcmi->vdev->entity);
>
> + dcmi_set_min_frequency(dcmi, FREQ_QOS_MIN_DEFAULT_VALUE);
> +
> spin_lock_irq(&dcmi->irqlock);
>
> /* Disable interruptions */
> @@ -1834,11 +1943,11 @@ static int dcmi_probe(struct platform_device *pdev)
> struct device_node *np = pdev->dev.of_node;
> const struct of_device_id *match = NULL;
> struct v4l2_fwnode_endpoint ep = { .bus_type = 0 };
> + struct irq_affinity_notify *notify;
> struct stm32_dcmi *dcmi;
> struct vb2_queue *q;
> struct dma_chan *chan;
> struct clk *mclk;
> - int irq;
> int ret = 0;
>
> match = of_match_device(of_match_ptr(stm32_dcmi_of_match), &pdev->dev);
> @@ -1879,9 +1988,9 @@ static int dcmi_probe(struct platform_device *pdev)
> dcmi->bus.bus_width = ep.bus.parallel.bus_width;
> dcmi->bus.data_shift = ep.bus.parallel.data_shift;
>
> - irq = platform_get_irq(pdev, 0);
> - if (irq <= 0)
> - return irq ? irq : -ENXIO;
> + dcmi->irq = platform_get_irq(pdev, 0);
> + if (dcmi->irq <= 0)
> + return dcmi->irq ? dcmi->irq : -ENXIO;
>
> dcmi->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> if (!dcmi->res) {
> @@ -1895,11 +2004,12 @@ static int dcmi_probe(struct platform_device *pdev)
> return PTR_ERR(dcmi->regs);
> }
>
> - ret = devm_request_threaded_irq(&pdev->dev, irq, dcmi_irq_callback,
> + ret = devm_request_threaded_irq(&pdev->dev, dcmi->irq,
> + dcmi_irq_callback,
> dcmi_irq_thread, IRQF_ONESHOT,
> dev_name(&pdev->dev), dcmi);
> if (ret) {
> - dev_err(&pdev->dev, "Unable to request irq %d\n", irq);
> + dev_err(&pdev->dev, "Unable to request irq %d\n", dcmi->irq);
> return ret;
> }
>
> @@ -1922,6 +2032,7 @@ static int dcmi_probe(struct platform_device *pdev)
> spin_lock_init(&dcmi->irqlock);
> mutex_init(&dcmi->lock);
> mutex_init(&dcmi->dma_lock);
> + mutex_init(&dcmi->freq_lock);
> init_completion(&dcmi->complete);
> INIT_LIST_HEAD(&dcmi->buffers);
>
> @@ -1930,6 +2041,13 @@ static int dcmi_probe(struct platform_device *pdev)
> dcmi->state = STOPPED;
> dcmi->dma_chan = chan;
>
> + if (!alloc_cpumask_var(&dcmi->boosted, GFP_KERNEL))
> + return -ENODEV;
> +
> + notify = &dcmi->notify;
> + notify->notify = dcmi_irq_notifier_notify;
> + notify->release = dcmi_irq_notifier_release;
> +
> q = &dcmi->queue;
>
> dcmi->v4l2_dev.mdev = &dcmi->mdev;
> @@ -2022,6 +2140,8 @@ static int dcmi_probe(struct platform_device *pdev)
>
> dev_info(&pdev->dev, "Probe done\n");
>
> + dcmi_get_min_frequency(dcmi);
> +
> platform_set_drvdata(pdev, dcmi);
>
> pm_runtime_enable(&pdev->dev);
> @@ -2049,6 +2169,8 @@ static int dcmi_remove(struct platform_device *pdev)
>
> pm_runtime_disable(&pdev->dev);
>
> + free_cpumask_var(dcmi->boosted);
> +
> v4l2_async_notifier_unregister(&dcmi->notifier);
> v4l2_async_notifier_cleanup(&dcmi->notifier);
> media_entity_cleanup(&dcmi->vdev->entity);
>
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