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Message-ID: <e2e46cae-d8dc-82ed-b9f5-f8520cf248a7@st.com>
Date: Wed, 24 Jun 2020 11:27:23 +0000
From: Benjamin GAIGNARD <benjamin.gaignard@...com>
To: Hugues FRUCHET <hugues.fruchet@...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
On 6/24/20 11:24 AM, Hugues FRUCHET wrote:
> 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)
FREQ_QOS_MIN_DEFAULT_VALUE value is zero so that won't change anything.
Thanks,
Benjamin
>> + /*
>> + * 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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