On Wed, May 20, 2015 at 07:12:25PM -0700, Matt Roper wrote:
> Various places in the driver need the ability to schedule actions to run
> on a future vblank (updating watermarks, unpinning buffers, etc.). The
> long term goal is to add such a mechanism in the DRM core that can be
> shared by all drivers. Paulo Zanoni has already written some
> preliminary patches to support this, but his work will probably take
> some time to polish and get merged since it needs to untangle the DRM
> core's vblank infrastructure. This patch is partially based on Paulo's
> work, but takes a simpler approach and just adds an i915-specific
> mechanism that can be used in the interim since we have an immediate
> need for watermark updates.
>
> Inspired-by: Paulo Zanoni <przan...@gmail.com>
> Signed-off-by: Matt Roper <matthew.d.ro...@intel.com>
I like what I had better. No needless kmallocs (this IMO is a must
requirement for any solution), no needless workqueues, uses the hw
vblank counter and absolute values so isn't racy.
> ---
> drivers/gpu/drm/i915/i915_irq.c | 117
> +++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_display.c | 8 +++
> drivers/gpu/drm/i915/intel_drv.h | 27 ++++++++
> 3 files changed, 152 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 557af88..fd5a795 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1649,8 +1649,37 @@ static void gen6_rps_irq_handler(struct
> drm_i915_private *dev_priv, u32 pm_iir)
> }
> }
>
> +static void process_vblank_jobs(struct drm_device *dev, enum pipe pipe)
> +{
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
> + struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> + struct i915_vblank_job *job, *tmp;
> + u32 seq;
> +
> + seq = drm_vblank_count(dev, pipe);
> + list_for_each_entry_safe(job, tmp, &intel_crtc->vblank_jobs, link) {
> + if (seq - job->seq > (1<<23))
> + continue;
> +
> + list_del(&job->link);
> + drm_vblank_put(dev, pipe);
> +
> + if (job->wq) {
> + job->fired_seq = seq;
> + queue_work(job->wq, &job->work);
> + } else {
> + job->callback(intel_crtc, job->callback_data,
> + false, seq);
> + kfree(job);
> + }
> + }
> +}
> +
> static bool intel_pipe_handle_vblank(struct drm_device *dev, enum pipe pipe)
> {
> + process_vblank_jobs(dev, pipe);
> +
> if (!drm_handle_vblank(dev, pipe))
> return false;
>
> @@ -4511,3 +4540,91 @@ void intel_runtime_pm_enable_interrupts(struct
> drm_i915_private *dev_priv)
> dev_priv->dev->driver->irq_preinstall(dev_priv->dev);
> dev_priv->dev->driver->irq_postinstall(dev_priv->dev);
> }
> +
> +static void vblank_job_handler(struct work_struct *work)
> +{
> + struct i915_vblank_job *job =
> + container_of(work, struct i915_vblank_job, work);
> +
> + job->callback(job->crtc, job->callback_data,
> + job->seq != job->fired_seq, job->fired_seq);
> + kfree(job);
> +}
> +
> +/**
> + * intel_schedule_vblank_job - schedule work to happen on specified vblank
> + * @crtc: CRTC whose vblank should trigger the work
> + * @callback: Code to run on vblank
> + * @callback_data: Data to pass to callback function
> + * @wq: Workqueue to run job on (or NULL to run from interrupt context)
> + * @seq: vblank count relative to current to schedule for
> + *
> + * Schedule code that should be run after the specified vblank fires. The
> code
> + * can either run directly in the interrupt context or on a specified
> + * workqueue.
> + */
> +int intel_schedule_vblank_job(struct intel_crtc *crtc,
> + i915_vblank_callback_t callback,
> + void *callback_data,
> + struct workqueue_struct *wq,
> + u32 seq)
> +{
> + struct drm_device *dev = crtc->base.dev;
> + struct i915_vblank_job *job;
> + unsigned long irqflags;
> + int ret;
> +
> + job = kzalloc(sizeof(*job), GFP_ATOMIC);
> + if (!job)
> + return -ENOMEM;
> +
> + job->wq = wq;
> + job->crtc = crtc;
> + job->callback = callback;
> + job->callback_data = callback_data;
> + if (job->wq)
> + INIT_WORK(&job->work, vblank_job_handler);
> +
> + ret = drm_crtc_vblank_get(&crtc->base);
> + if (ret) {
> + DRM_DEBUG_KMS("Failed to enable interrupts, ret=%d\n", ret);
> + kfree(job);
> + return -EINVAL;
> + }
> +
> + spin_lock_irqsave(&dev->event_lock, irqflags);
> + job->seq = seq + drm_vblank_count(dev, crtc->pipe);
> + list_add_tail(&job->link, &crtc->vblank_jobs);
> + spin_unlock_irqrestore(&dev->event_lock, irqflags);
> +
> + return 0;
> +}
> +
> +/**
> + * intel_trigger_all_vblank_jobs - immediately trigger vblank jobs for a crtc
> + * @crtc: CRTC to trigger all outstanding jobs for
> + *
> + * Immediately triggers all of the jobs awaiting future vblanks on a CRTC.
> + * This will be called when a CRTC is disabled (because there may never be
> + * another vblank event). The job callbacks will receive 'true' for the
> + * early parameter, as well as the current vblank count.
> + */
> +void trigger_all_vblank_jobs(struct intel_crtc *crtc)
> +{
> + struct i915_vblank_job *job, *tmp;
> + u32 seq;
> +
> + seq = drm_vblank_count(crtc->base.dev, crtc->pipe);
> + list_for_each_entry_safe(job, tmp, &crtc->vblank_jobs, link) {
> + list_del(&job->link);
> + drm_vblank_put(crtc->base.dev, crtc->pipe);
> +
> + if (job->wq) {
> + job->fired_seq = seq;
> + queue_work(job->wq, &job->work);
> + } else {
> + job->callback(crtc, job->callback_data, true, seq);
> + kfree(job);
> + }
> + }
> +}
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index 76affba..9b56d07 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5099,6 +5099,8 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
> if (!intel_crtc->active)
> return;
>
> + trigger_all_vblank_jobs(intel_crtc);
> +
> for_each_encoder_on_crtc(dev, crtc, encoder)
> encoder->disable(encoder);
>
> @@ -5161,6 +5163,8 @@ static void haswell_crtc_disable(struct drm_crtc *crtc)
> if (!intel_crtc->active)
> return;
>
> + trigger_all_vblank_jobs(intel_crtc);
> +
> for_each_encoder_on_crtc(dev, crtc, encoder) {
> intel_opregion_notify_encoder(encoder, false);
> encoder->disable(encoder);
> @@ -6004,6 +6008,8 @@ static void i9xx_crtc_disable(struct drm_crtc *crtc)
> if (!intel_crtc->active)
> return;
>
> + trigger_all_vblank_jobs(intel_crtc);
> +
> /*
> * On gen2 planes are double buffered but the pipe isn't, so we must
> * wait for planes to fully turn off before disabling the pipe.
> @@ -13649,6 +13655,8 @@ static void intel_crtc_init(struct drm_device *dev,
> int pipe)
>
> drm_crtc_helper_add(&intel_crtc->base, &intel_helper_funcs);
>
> + INIT_LIST_HEAD(&intel_crtc->vblank_jobs);
> +
> WARN_ON(drm_crtc_index(&intel_crtc->base) != intel_crtc->pipe);
> return;
>
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index 627741a..630e7c1 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -504,6 +504,24 @@ struct intel_crtc_atomic_commit {
> unsigned update_sprite_watermarks;
> };
>
> +typedef void (*i915_vblank_callback_t)(struct intel_crtc *crtc,
> + void *data,
> + bool early,
> + u32 fired_seq);
> +
> +/* Task to run (or schedule on a workqueue) on a specific vblank */
> +struct i915_vblank_job {
> + u32 seq;
> + u32 fired_seq; /* early if crtc gets disabled */
> + struct intel_crtc *crtc;
> + struct workqueue_struct *wq; /* NULL = run from interrupt */
> + i915_vblank_callback_t callback;
> + void *callback_data;
> +
> + struct list_head link;
> + struct work_struct work;
> +};
> +
> struct intel_crtc {
> struct drm_crtc base;
> enum pipe pipe;
> @@ -550,6 +568,9 @@ struct intel_crtc {
>
> /* scalers available on this crtc */
> int num_scalers;
> +
> + /* Jobs to run/schedule on vblank */
> + struct list_head vblank_jobs;
> };
>
> struct intel_plane_wm_parameters {
> @@ -913,6 +934,12 @@ static inline bool intel_irqs_enabled(struct
> drm_i915_private *dev_priv)
> int intel_get_crtc_scanline(struct intel_crtc *crtc);
> void gen8_irq_power_well_post_enable(struct drm_i915_private *dev_priv,
> unsigned int pipe_mask);
> +int intel_schedule_vblank_job(struct intel_crtc *crtc,
> + i915_vblank_callback_t callback,
> + void *callback_data,
> + struct workqueue_struct *wq,
> + u32 seq);
> +void trigger_all_vblank_jobs(struct intel_crtc *crtc);
>
> /* intel_crt.c */
> void intel_crt_init(struct drm_device *dev);
> --
> 1.8.5.1
>
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--
Ville Syrjälä
Intel OTC
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