On Sat, Aug 31, 2024 at 05:15:06PM +0200, Jacopo Mondi wrote:
> On Sat, Aug 31, 2024 at 05:39:09PM GMT, Laurent Pinchart wrote:
> > 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 ?
>
> Ah no but I did
> scoped_guard(spin_lock
> and it didn't compile so I though only spinlock_irqsave was valid :/
>
> > > + 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
>
> Isn't this done here ? :)
Not that I can see. You only change the lock functions in
pispbe_prepare_job().
> > the lock completely, now that ready_queue is only accessed from vb2 ops
> > all protected by the vb2 queue lock ?
>
> Ah probably yes. And probably in prepare_job() too as it is only
> called from vb2 ops callbacks
>
> This would really simplify the code
>
> > > }
> > >
> > > - 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.
>
> I know, but it makes backporting the patch to the BSP which has
> multi-group support quite impossible. As this doesn't have any
> performance impact I would keep it this way to ease backporting
You know my opinion about BSPs :-) I'm OK keeping this for a bit longer
until we implement proper multi-context support in mainline, assuming it
can be done in a reasonable time frame.
> > 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.
>
> I would refrain from touching that part of the code for little gain :)
Once queue_job gets replaced with a pointer that code will need to be
touched, but we can wait until then.
> > > +
> > > + 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
