Re: [PATCH] media: chips-media: wave5: Add hrtimer based polling support

From: Devarsh Thakkar
Date: Mon Feb 12 2024 - 07:39:27 EST

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Gentle reminder.

On 25/01/24 18:38, Devarsh Thakkar wrote:
> Add support for starting a polling timer in case interrupt is not
> available. This helps keep the VPU functional in SoC's such as AM62A, where
> the hardware interrupt hookup may not be present due to an SoC errata [1].
>
> The timer is shared across all instances of encoder and decoder and is
> started when first instance of encoder or decoder is opened and stopped
> when last instance is closed, thus avoiding per instance polling and saving
> CPU bandwidth.
>
> hrtimer callback is called with 5ms polling interval while any of the
> encoder/decoder instances are running to check the interrupt status as
> being done in irq handler.
>
> Based on above interrupt status, use a worker thread to iterate over the
> interrupt status for each instance and send completion event as being done
> in irq thread function.
>
> Parse for irq number before v4l2 device registration and if not available
> only then, initialize hrtimer and worker thread.
>
> Move the core functionality of irq thread function to a separate function
> wave5_vpu_handle_irq so that it can be used by both the worker thread when
> using polling mode and irq thread when using interrupt mode.
>
> Protect hrtimer access and instance list with device specific mutex locks
> to avoid race conditions while different instances of encoder and decoder
> are started together.
>
> Add module param to change polling interval for debug purpose.
>
> [1] https://www.ti.com/lit/pdf/spruj16
> (Ref: Section 4.2.3.3 Resets, Interrupts, and Clocks)
>
> Signed-off-by: Devarsh Thakkar <devarsht@xxxxxx>
> ---
> Test logs:
> https://gist.github.com/devarsht/613bc8aa66e65814c8374ffb6a4f50fb
> ---
> .../platform/chips-media/wave5/wave5-helper.c | 16 ++-
> .../chips-media/wave5/wave5-vpu-dec.c | 13 +-
> .../chips-media/wave5/wave5-vpu-enc.c | 13 +-
> .../platform/chips-media/wave5/wave5-vpu.c | 117 ++++++++++++------
> .../platform/chips-media/wave5/wave5-vpuapi.h | 4 +
> 5 files changed, 122 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/media/platform/chips-media/wave5/wave5-helper.c b/drivers/media/platform/chips-media/wave5/wave5-helper.c
> index 8433ecab230c..475b7628964f 100644
> --- a/drivers/media/platform/chips-media/wave5/wave5-helper.c
> +++ b/drivers/media/platform/chips-media/wave5/wave5-helper.c
> @@ -52,6 +52,8 @@ int wave5_vpu_release_device(struct file *filp,
> char *name)
> {
> struct vpu_instance *inst = wave5_to_vpu_inst(filp->private_data);
> + struct vpu_device *dev = inst->dev;
> + int ret = 0;
>
> v4l2_m2m_ctx_release(inst->v4l2_fh.m2m_ctx);
> if (inst->state != VPU_INST_STATE_NONE) {
> @@ -71,8 +73,20 @@ int wave5_vpu_release_device(struct file *filp,
> }
>
> wave5_cleanup_instance(inst);
> + if (dev->irq < 0) {
> + ret = mutex_lock_interruptible(&dev->dev_lock);
> + if (ret)
> + return ret;
>
> - return 0;
> + if (list_empty(&dev->instances)) {
> + dev_dbg(dev->dev, "Disabling the hrtimer\n");
> + hrtimer_cancel(&dev->hrtimer);
> + }
> +
> + mutex_unlock(&dev->dev_lock);
> + }
> +
> + return ret;
> }
>
> int wave5_vpu_queue_init(void *priv, struct vb2_queue *src_vq, struct vb2_queue *dst_vq,
> diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c b/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c
> index ef227af72348..c8624c681fa6 100644
> --- a/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c
> +++ b/drivers/media/platform/chips-media/wave5/wave5-vpu-dec.c
> @@ -1810,7 +1810,6 @@ static int wave5_vpu_open_dec(struct file *filp)
> v4l2_fh_add(&inst->v4l2_fh);
>
> INIT_LIST_HEAD(&inst->list);
> - list_add_tail(&inst->list, &dev->instances);
>
> inst->v4l2_m2m_dev = inst->dev->v4l2_m2m_dec_dev;
> inst->v4l2_fh.m2m_ctx =
> @@ -1867,6 +1866,18 @@ static int wave5_vpu_open_dec(struct file *filp)
>
> wave5_vdi_allocate_sram(inst->dev);
>
> + ret = mutex_lock_interruptible(&dev->dev_lock);
> + if (ret)
> + goto cleanup_inst;
> +
> + if (dev->irq < 0 && !hrtimer_active(&dev->hrtimer) && list_empty(&dev->instances))
> + hrtimer_start(&dev->hrtimer, ns_to_ktime(dev->vpu_poll_interval * NSEC_PER_MSEC),
> + HRTIMER_MODE_REL_PINNED);
> +
> + list_add_tail(&inst->list, &dev->instances);
> +
> + mutex_unlock(&dev->dev_lock);
> +
> return 0;
>
> cleanup_inst:
> diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpu-enc.c b/drivers/media/platform/chips-media/wave5/wave5-vpu-enc.c
> index f29cfa3af94a..9e88424761b6 100644
> --- a/drivers/media/platform/chips-media/wave5/wave5-vpu-enc.c
> +++ b/drivers/media/platform/chips-media/wave5/wave5-vpu-enc.c
> @@ -1554,7 +1554,6 @@ static int wave5_vpu_open_enc(struct file *filp)
> v4l2_fh_add(&inst->v4l2_fh);
>
> INIT_LIST_HEAD(&inst->list);
> - list_add_tail(&inst->list, &dev->instances);
>
> inst->v4l2_m2m_dev = inst->dev->v4l2_m2m_enc_dev;
> inst->v4l2_fh.m2m_ctx =
> @@ -1729,6 +1728,18 @@ static int wave5_vpu_open_enc(struct file *filp)
>
> wave5_vdi_allocate_sram(inst->dev);
>
> + ret = mutex_lock_interruptible(&dev->dev_lock);
> + if (ret)
> + goto cleanup_inst;
> +
> + if (dev->irq < 0 && !hrtimer_active(&dev->hrtimer) && list_empty(&dev->instances))
> + hrtimer_start(&dev->hrtimer, ns_to_ktime(dev->vpu_poll_interval * NSEC_PER_MSEC),
> + HRTIMER_MODE_REL_PINNED);
> +
> + list_add_tail(&inst->list, &dev->instances);
> +
> + mutex_unlock(&dev->dev_lock);
> +
> return 0;
>
> cleanup_inst:
> diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpu.c b/drivers/media/platform/chips-media/wave5/wave5-vpu.c
> index bfe4caa79cc9..968ec9baf1ef 100644
> --- a/drivers/media/platform/chips-media/wave5/wave5-vpu.c
> +++ b/drivers/media/platform/chips-media/wave5/wave5-vpu.c
> @@ -26,6 +26,9 @@ struct wave5_match_data {
> const char *fw_name;
> };
>
> +static int vpu_poll_interval = 5;
> +module_param(vpu_poll_interval, int, 0644);
> +
> int wave5_vpu_wait_interrupt(struct vpu_instance *inst, unsigned int timeout)
> {
> int ret;
> @@ -40,7 +43,7 @@ int wave5_vpu_wait_interrupt(struct vpu_instance *inst, unsigned int timeout)
> return 0;
> }
>
> -static irqreturn_t wave5_vpu_irq_thread(int irq, void *dev_id)
> +static void wave5_vpu_handle_irq(void *dev_id)
> {
> u32 seq_done;
> u32 cmd_done;
> @@ -48,42 +51,67 @@ static irqreturn_t wave5_vpu_irq_thread(int irq, void *dev_id)
> struct vpu_instance *inst;
> struct vpu_device *dev = dev_id;
>
> - if (wave5_vdi_read_register(dev, W5_VPU_VPU_INT_STS)) {
> - irq_reason = wave5_vdi_read_register(dev, W5_VPU_VINT_REASON);
> - wave5_vdi_write_register(dev, W5_VPU_VINT_REASON_CLR, irq_reason);
> - wave5_vdi_write_register(dev, W5_VPU_VINT_CLEAR, 0x1);
> -
> - list_for_each_entry(inst, &dev->instances, list) {
> - seq_done = wave5_vdi_read_register(dev, W5_RET_SEQ_DONE_INSTANCE_INFO);
> - cmd_done = wave5_vdi_read_register(dev, W5_RET_QUEUE_CMD_DONE_INST);
> -
> - if (irq_reason & BIT(INT_WAVE5_INIT_SEQ) ||
> - irq_reason & BIT(INT_WAVE5_ENC_SET_PARAM)) {
> - if (seq_done & BIT(inst->id)) {
> - seq_done &= ~BIT(inst->id);
> - wave5_vdi_write_register(dev, W5_RET_SEQ_DONE_INSTANCE_INFO,
> - seq_done);
> - complete(&inst->irq_done);
> - }
> + irq_reason = wave5_vdi_read_register(dev, W5_VPU_VINT_REASON);
> + wave5_vdi_write_register(dev, W5_VPU_VINT_REASON_CLR, irq_reason);
> + wave5_vdi_write_register(dev, W5_VPU_VINT_CLEAR, 0x1);
> +
> + list_for_each_entry(inst, &dev->instances, list) {
> + seq_done = wave5_vdi_read_register(dev, W5_RET_SEQ_DONE_INSTANCE_INFO);
> + cmd_done = wave5_vdi_read_register(dev, W5_RET_QUEUE_CMD_DONE_INST);
> +
> + if (irq_reason & BIT(INT_WAVE5_INIT_SEQ) ||
> + irq_reason & BIT(INT_WAVE5_ENC_SET_PARAM)) {
> + if (seq_done & BIT(inst->id)) {
> + seq_done &= ~BIT(inst->id);
> + wave5_vdi_write_register(dev, W5_RET_SEQ_DONE_INSTANCE_INFO,
> + seq_done);
> + complete(&inst->irq_done);
> }
> + }
>
> - if (irq_reason & BIT(INT_WAVE5_DEC_PIC) ||
> - irq_reason & BIT(INT_WAVE5_ENC_PIC)) {
> - if (cmd_done & BIT(inst->id)) {
> - cmd_done &= ~BIT(inst->id);
> - wave5_vdi_write_register(dev, W5_RET_QUEUE_CMD_DONE_INST,
> - cmd_done);
> - inst->ops->finish_process(inst);
> - }
> + if (irq_reason & BIT(INT_WAVE5_DEC_PIC) ||
> + irq_reason & BIT(INT_WAVE5_ENC_PIC)) {
> + if (cmd_done & BIT(inst->id)) {
> + cmd_done &= ~BIT(inst->id);
> + wave5_vdi_write_register(dev, W5_RET_QUEUE_CMD_DONE_INST,
> + cmd_done);
> + inst->ops->finish_process(inst);
> }
> -
> - wave5_vpu_clear_interrupt(inst, irq_reason);
> }
> +
> + wave5_vpu_clear_interrupt(inst, irq_reason);
> }
> +}
> +
> +static irqreturn_t wave5_vpu_irq_thread(int irq, void *dev_id)
> +{
> + struct vpu_device *dev = dev_id;
> +
> + if (wave5_vdi_read_register(dev, W5_VPU_VPU_INT_STS))
> + wave5_vpu_handle_irq(dev);
>
> return IRQ_HANDLED;
> }
>
> +static void wave5_vpu_irq_work_fn(struct kthread_work *work)
> +{
> + struct vpu_device *dev = container_of(work, struct vpu_device, work);
> +
> + if (wave5_vdi_read_register(dev, W5_VPU_VPU_INT_STS))
> + wave5_vpu_handle_irq(dev);
> +}
> +
> +static enum hrtimer_restart wave5_vpu_timer_callback(struct hrtimer *timer)
> +{
> + struct vpu_device *dev =
> + container_of(timer, struct vpu_device, hrtimer);
> +
> + kthread_queue_work(dev->worker, &dev->work);
> + hrtimer_forward_now(timer, ns_to_ktime(vpu_poll_interval * NSEC_PER_MSEC));
> +
> + return HRTIMER_RESTART;
> +}
> +
> static int wave5_vpu_load_firmware(struct device *dev, const char *fw_name,
> u32 *revision)
> {
> @@ -209,16 +237,24 @@ static int wave5_vpu_probe(struct platform_device *pdev)
>
> dev->irq = platform_get_irq(pdev, 0);
> if (dev->irq < 0) {
> - dev_err(&pdev->dev, "failed to get irq resource\n");
> - ret = -ENXIO;
> - goto err_enc_unreg;
> - }
> -
> - ret = devm_request_threaded_irq(&pdev->dev, dev->irq, NULL,
> - wave5_vpu_irq_thread, IRQF_ONESHOT, "vpu_irq", dev);
> - if (ret) {
> - dev_err(&pdev->dev, "Register interrupt handler, fail: %d\n", ret);
> - goto err_enc_unreg;
> + dev_err(&pdev->dev, "failed to get irq resource, falling back to polling\n");
> + hrtimer_init(&dev->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
> + dev->hrtimer.function = &wave5_vpu_timer_callback;
> + dev->worker = kthread_create_worker(0, "vpu_irq_thread");
> + if (IS_ERR(dev->worker)) {
> + dev_err(&pdev->dev, "failed to create vpu irq worker\n");
> + ret = PTR_ERR(dev->worker);
> + goto err_vdi_release;
> + }
> + dev->vpu_poll_interval = vpu_poll_interval;
> + kthread_init_work(&dev->work, wave5_vpu_irq_work_fn);
> + } else {
> + ret = devm_request_threaded_irq(&pdev->dev, dev->irq, NULL,
> + wave5_vpu_irq_thread, IRQF_ONESHOT, "vpu_irq", dev);
> + if (ret) {
> + dev_err(&pdev->dev, "Register interrupt handler, fail: %d\n", ret);
> + goto err_enc_unreg;
> + }
> }
>
> ret = wave5_vpu_load_firmware(&pdev->dev, match_data->fw_name, &fw_revision);
> @@ -254,6 +290,11 @@ static int wave5_vpu_remove(struct platform_device *pdev)
> {
> struct vpu_device *dev = dev_get_drvdata(&pdev->dev);
>
> + if (dev->irq < 0) {
> + kthread_destroy_worker(dev->worker);
> + hrtimer_cancel(&dev->hrtimer);
> + }
> +
> mutex_destroy(&dev->dev_lock);
> mutex_destroy(&dev->hw_lock);
> clk_bulk_disable_unprepare(dev->num_clks, dev->clks);
> diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpuapi.h b/drivers/media/platform/chips-media/wave5/wave5-vpuapi.h
> index 352f6e904e50..edc50450ddb8 100644
> --- a/drivers/media/platform/chips-media/wave5/wave5-vpuapi.h
> +++ b/drivers/media/platform/chips-media/wave5/wave5-vpuapi.h
> @@ -756,6 +756,10 @@ struct vpu_device {
> u32 product_code;
> struct ida inst_ida;
> struct clk_bulk_data *clks;
> + struct hrtimer hrtimer;
> + struct kthread_work work;
> + struct kthread_worker *worker;
> + int vpu_poll_interval;
> int num_clks;
> };
>

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