Hi Jacopo,
Thank you for the patch.
On Tue, Aug 27, 2024 at 09:40:17AM +0200, Jacopo Mondi wrote:
> Currently the 'pispbe_schedule()' function does two things:
>
> 1) Tries to assemble a job by inspecting all the video node queues
> to make sure all the required buffers are available
> 2) Submit the job to the hardware
>
> The pispbe_schedule() function is called at:
>
> - video device start_streaming() time
> - video device qbuf() time
> - irq handler
>
> As assembling a job requires inspecting all queues, it is a rather
> time consuming operation which is better not run in IRQ context.
>
> To avoid the executing the time consuming job creation in interrupt
> context split the job creation and job scheduling in two distinct
> operations. When a well-formed job is created, append it to the
> newly introduced 'pispbe->job_queue' where it will be dequeued from
> by the scheduling routine.
>
> At start_streaming() and qbuf() time immediately try to schedule a job
> if one has been created as the irq handler routing is only called when
> a job has completed, and we can't solely rely on it for scheduling new
> jobs.
>
> Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
> ---
> .../platform/raspberrypi/pisp_be/pisp_be.c | 137 +++++++++++-------
> 1 file changed, 83 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/media/platform/raspberrypi/pisp_be/pisp_be.c b/drivers/media/platform/raspberrypi/pisp_be/pisp_be.c
> index 73a5c88e25d0..f42541bb4827 100644
> --- a/drivers/media/platform/raspberrypi/pisp_be/pisp_be.c
> +++ b/drivers/media/platform/raspberrypi/pisp_be/pisp_be.c
> @@ -190,6 +190,8 @@ struct pispbe_hw_enables {
>
> /* Records a job configuration and memory addresses. */
> struct pispbe_job_descriptor {
> + struct list_head queue;
> + struct pispbe_buffer *buffers[PISPBE_NUM_NODES];
> dma_addr_t hw_dma_addrs[N_HW_ADDRESSES];
> struct pisp_be_tiles_config *config;
A candidate for a separate patch, I think storage for
pisp_be_tiles_config should be moved from pisbbe_dev.config to
pispbe_buffer, like we do for the rkisp1 driver. The memory would be
allocated at buffer allocation time (for config node buffers only, of
course).
> struct pispbe_hw_enables hw_enables;
> @@ -215,8 +217,10 @@ struct pispbe_dev {
> unsigned int sequence;
> u32 streaming_map;
> struct pispbe_job queued_job, running_job;
> - spinlock_t hw_lock; /* protects "hw_busy" flag and streaming_map */
> + /* protects "hw_busy" flag, streaming_map and job_queue*/
s/job_queue/job_queue /
I don't think streaming_map needs to be protected by the spinlock
anymore. It is now accessed only from the qbuf, start_streaming and
stop_streaming operations, which are all protected by the vb2 queue
mutex... scratch that, we use a different mutex for different video
devices.
> + spinlock_t hw_lock;
> bool hw_busy; /* non-zero if a job is queued or is being started */
> + struct list_head job_queue;
> int irq;
> u32 hw_version;
> u8 done, started;
> @@ -440,41 +444,50 @@ static void pispbe_xlate_addrs(struct pispbe_dev *pispbe,
> * For Output0, Output1, Tdn and Stitch, a buffer only needs to be
> * available if the blocks are enabled in the config.
> *
> - * Needs to be called with hw_lock held.
> + * If all the buffers required to form a job are available, append the
> + * job descriptor to the job queue to be later queued to the HW.
> *
> * Returns 0 if a job has been successfully prepared, < 0 otherwise.
> */
> -static int pispbe_prepare_job(struct pispbe_dev *pispbe,
> - struct pispbe_job_descriptor *job)
> +static int pispbe_prepare_job(struct pispbe_dev *pispbe)
> {
> struct pispbe_buffer *buf[PISPBE_NUM_NODES] = {};
> + struct pispbe_job_descriptor *job;
> + unsigned int streaming_map;
> unsigned int config_index;
> struct pispbe_node *node;
> - unsigned long flags;
>
> - lockdep_assert_held(&pispbe->hw_lock);
> + scoped_guard(spinlock_irqsave, &pispbe->hw_lock) {
Do you need the irqsave version ?
> + static const u32 mask = BIT(CONFIG_NODE) | BIT(MAIN_INPUT_NODE);
>
> - memset(job, 0, sizeof(struct pispbe_job_descriptor));
> + if ((pispbe->streaming_map & mask) != mask)
> + return -ENODEV;
>
> - if (((BIT(CONFIG_NODE) | BIT(MAIN_INPUT_NODE)) &
> - pispbe->streaming_map) !=
> - (BIT(CONFIG_NODE) | BIT(MAIN_INPUT_NODE)))
> - return -ENODEV;
> + /*
> + * Take a copy of streaming_map: nodes activated after this
> + * point are ignored when preparing this job.
> + */
> + streaming_map = pispbe->streaming_map;
> + }
> +
> + job = kzalloc(sizeof(*job), GFP_KERNEL);
> + if (!job)
> + return -ENOMEM;
>
> node = &pispbe->node[CONFIG_NODE];
> - spin_lock_irqsave(&node->ready_lock, flags);
> - buf[CONFIG_NODE] = list_first_entry_or_null(&node->ready_queue,
> - struct pispbe_buffer,
> - ready_list);
> - if (buf[CONFIG_NODE]) {
> +
> + scoped_guard(spinlock_irqsave, &node->ready_lock) {
Same here.
> + buf[CONFIG_NODE] = list_first_entry_or_null(&node->ready_queue,
> + struct pispbe_buffer,
> + ready_list);
> + if (!buf[CONFIG_NODE]) {
> + kfree(job);
> + return -ENODEV;
> + }
> +
> list_del(&buf[CONFIG_NODE]->ready_list);
> - pispbe->queued_job.buf[CONFIG_NODE] = buf[CONFIG_NODE];
> + job->buffers[CONFIG_NODE] = buf[CONFIG_NODE];
> }
> - spin_unlock_irqrestore(&node->ready_lock, flags);
> -
> - /* Exit early if no config buffer has been queued. */
> - if (!buf[CONFIG_NODE])
> - return -ENODEV;
>
> config_index = buf[CONFIG_NODE]->vb.vb2_buf.index;
> job->config = &pispbe->config[config_index];
> @@ -495,7 +508,7 @@ static int pispbe_prepare_job(struct pispbe_dev *pispbe,
> continue;
>
> buf[i] = NULL;
> - if (!(pispbe->streaming_map & BIT(i)))
> + if (!(streaming_map & BIT(i)))
> continue;
>
> if ((!(rgb_en & PISP_BE_RGB_ENABLE_OUTPUT0) &&
> @@ -522,25 +535,27 @@ static int pispbe_prepare_job(struct pispbe_dev *pispbe,
> node = &pispbe->node[i];
>
> /* Pull a buffer from each V4L2 queue to form the queued job */
> - spin_lock_irqsave(&node->ready_lock, flags);
> + spin_lock(&node->ready_lock);
> buf[i] = list_first_entry_or_null(&node->ready_queue,
> struct pispbe_buffer,
> ready_list);
> if (buf[i]) {
> list_del(&buf[i]->ready_list);
> - pispbe->queued_job.buf[i] = buf[i];
> + job->buffers[i] = buf[i];
> }
> - spin_unlock_irqrestore(&node->ready_lock, flags);
> + spin_unlock(&node->ready_lock);
>
> if (!buf[i] && !ignore_buffers)
The ignore_buffers logic seems weird to me. I don't understand why we
take buffers out of the ready_queue for the nodes that are not used by
this job. The problem isn't related to this patch, so it can be fixed
separately.
> goto err_return_buffers;
> }
>
> - pispbe->queued_job.valid = true;
> -
> /* Convert buffers to DMA addresses for the hardware */
> pispbe_xlate_addrs(pispbe, job, buf);
>
> + spin_lock(&pispbe->hw_lock);
> + list_add_tail(&job->queue, &pispbe->job_queue);
> + spin_unlock(&pispbe->hw_lock);
> +
> return 0;
>
> err_return_buffers:
> @@ -551,33 +566,41 @@ static int pispbe_prepare_job(struct pispbe_dev *pispbe,
> continue;
>
> /* Return the buffer to the ready_list queue */
> - spin_lock_irqsave(&n->ready_lock, flags);
> + spin_lock(&n->ready_lock);
> list_add(&buf[i]->ready_list, &n->ready_queue);
> - spin_unlock_irqrestore(&n->ready_lock, flags);
> + spin_unlock(&n->ready_lock);
Should pispbe_node_buffer_queue() and pispbe_node_stop_streaming()
switch away from spin_lock_irqsave() too then ? Actually, can't we drop
the lock completely, now that ready_queue is only accessed from vb2 ops
all protected by the vb2 queue lock ?
> }
>
> - memset(&pispbe->queued_job, 0, sizeof(pispbe->queued_job));
> + kfree(job);
>
> return -ENODEV;
> }
>
> static void pispbe_schedule(struct pispbe_dev *pispbe, bool clear_hw_busy)
> {
> - struct pispbe_job_descriptor job;
> - unsigned long flags;
> - int ret;
> + struct pispbe_job_descriptor *job;
>
> - spin_lock_irqsave(&pispbe->hw_lock, flags);
> + scoped_guard(spinlock_irqsave, &pispbe->hw_lock) {
> + if (clear_hw_busy)
> + pispbe->hw_busy = false;
>
> - if (clear_hw_busy)
> - pispbe->hw_busy = false;
> + if (pispbe->hw_busy)
> + return;
>
> - if (pispbe->hw_busy)
> - goto unlock_and_return;
> + job = list_first_entry_or_null(&pispbe->job_queue,
> + struct pispbe_job_descriptor,
> + queue);
> + if (!job)
> + return;
>
> - ret = pispbe_prepare_job(pispbe, &job);
> - if (ret)
> - goto unlock_and_return;
> + list_del(&job->queue);
> +
> + for (unsigned int i = 0; i < PISPBE_NUM_NODES; i++)
> + pispbe->queued_job.buf[i] = job->buffers[i];
> + pispbe->queued_job.valid = true;
Ideally this should be replaced with a pointer to the job descriptor,
but it can be done in a second step.
Ideally also, this should go to pispbe_queue_job(). I however don't
understand the logic that handles queued_job in pispbe_isr() and why the
interrupt handler can complete the queued job in some circumstances, so
I'm not sure how it would interact with moving this code to the
pispbe_queue_job() function.
> +
> + pispbe->hw_busy = true;
> + }
>
> /*
> * We can kick the job off without the hw_lock, as this can
> @@ -585,16 +608,8 @@ static void pispbe_schedule(struct pispbe_dev *pispbe, bool clear_hw_busy)
> * only when the following job has been queued and an interrupt
> * is rised.
> */
> - pispbe->hw_busy = true;
> - spin_unlock_irqrestore(&pispbe->hw_lock, flags);
> -
> - pispbe_queue_job(pispbe, &job);
> -
> - return;
> -
> -unlock_and_return:
> - /* No job has been queued, just release the lock and return. */
> - spin_unlock_irqrestore(&pispbe->hw_lock, flags);
> + pispbe_queue_job(pispbe, job);
> + kfree(job);
> }
>
> static void pispbe_isr_jobdone(struct pispbe_dev *pispbe,
> @@ -857,7 +872,8 @@ static void pispbe_node_buffer_queue(struct vb2_buffer *buf)
> * Every time we add a buffer, check if there's now some work for the hw
> * to do.
> */
> - pispbe_schedule(pispbe, false);
> + if (!pispbe_prepare_job(pispbe))
> + pispbe_schedule(pispbe, false);
> }
>
> static int pispbe_node_start_streaming(struct vb2_queue *q, unsigned int count)
> @@ -883,7 +899,8 @@ static int pispbe_node_start_streaming(struct vb2_queue *q, unsigned int count)
> node->pispbe->streaming_map);
>
> /* Maybe we're ready to run. */
> - pispbe_schedule(pispbe, false);
> + if (!pispbe_prepare_job(pispbe))
> + pispbe_schedule(pispbe, false);
>
> return 0;
>
> @@ -935,6 +952,16 @@ static void pispbe_node_stop_streaming(struct vb2_queue *q)
>
> spin_lock_irqsave(&pispbe->hw_lock, flags);
> pispbe->streaming_map &= ~BIT(node->id);
> +
> + /* Release all jobs once all nodes have stopped streaming. */
> + if (pispbe->streaming_map == 0) {
> + struct pispbe_job_descriptor *job, *temp;
> +
> + list_for_each_entry_safe(job, temp, &pispbe->job_queue, queue) {
> + list_del(&job->queue);
> + kfree(job);
> + }
> + }
> spin_unlock_irqrestore(&pispbe->hw_lock, flags);
>
> pm_runtime_mark_last_busy(pispbe->dev);
> @@ -1677,6 +1704,8 @@ static int pispbe_probe(struct platform_device *pdev)
> if (!pispbe)
> return -ENOMEM;
>
> + INIT_LIST_HEAD(&pispbe->job_queue);
> +
> dev_set_drvdata(&pdev->dev, pispbe);
> pispbe->dev = &pdev->dev;
> platform_set_drvdata(pdev, pispbe);
--
Regards,
Laurent Pinchart
