[PATCH 1/2] drm/msm: use common display thread for dispatching vblank events

Jeykumar Sankaran
2018-11-01T00:19:04Z

DPU was using one thread per display to dispatch async
commits and vblank requests. Since clean up already happened
in msm to use the common thread for all the display commits,
display threads are only used to cater vblank requests. Single
thread is sufficient to do the job without any performance hits.

Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 6 +---
drivers/gpu/drm/msm/msm_drv.c | 50 ++++++++++++-----------------
drivers/gpu/drm/msm/msm_drv.h | 2 +-
3 files changed, 23 insertions(+), 35 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index 82c55ef..aff20f5 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -753,11 +753,7 @@ static int dpu_encoder_resource_control(struct drm_encoder *drm_enc,
is_vid_mode = dpu_enc->disp_info.capabilities &
MSM_DISPLAY_CAP_VID_MODE;

- if (drm_enc->crtc->index >= ARRAY_SIZE(priv->disp_thread)) {
- DPU_ERROR("invalid crtc index\n");
- return -EINVAL;
- }
- disp_thread = &priv->disp_thread[drm_enc->crtc->index];
+ disp_thread = &priv->disp_thread;

/*
* when idle_pc is not supported, process only KICKOFF, STOP and MODESET
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 9c9f7ff..1f384b3 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -257,8 +257,7 @@ static int vblank_ctrl_queue_work(struct msm_drm_private *priv,
list_add_tail(&vbl_ev->node, &vbl_ctrl->event_list);
spin_unlock_irqrestore(&vbl_ctrl->lock, flags);

- kthread_queue_work(&priv->disp_thread[crtc_id].worker,
- &vbl_ctrl->work);
+ kthread_queue_work(&priv->disp_thread.worker, &vbl_ctrl->work);

return 0;
}
@@ -284,14 +283,12 @@ static int msm_drm_uninit(struct device *dev)
kfree(vbl_ev);
}

+ kthread_flush_worker(&priv->disp_thread.worker);
+ kthread_stop(priv->disp_thread.thread);
+ priv->disp_thread.thread = NULL;
+
/* clean up display commit/event worker threads */
for (i = 0; i < priv->num_crtcs; i++) {
- if (priv->disp_thread[i].thread) {
- kthread_flush_worker(&priv->disp_thread[i].worker);
- kthread_stop(priv->disp_thread[i].thread);
- priv->disp_thread[i].thread = NULL;
- }
-
if (priv->event_thread[i].thread) {
kthread_flush_worker(&priv->event_thread[i].worker);
kthread_stop(priv->event_thread[i].thread);
@@ -537,6 +534,22 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
ddev->mode_config.funcs = &mode_config_funcs;
ddev->mode_config.helper_private = &mode_config_helper_funcs;

+ /* initialize display thread */
+ kthread_init_worker(&priv->disp_thread.worker);
+ priv->disp_thread.dev = ddev;
+ priv->disp_thread.thread = kthread_run(kthread_worker_fn,
+ &priv->disp_thread.worker,
+ "disp_thread");
+ if (IS_ERR(priv->disp_thread.thread)) {
+ DRM_DEV_ERROR(dev, "failed to create crtc_commit kthread\n");
+ priv->disp_thread.thread = NULL;
+ goto err_msm_uninit;
+ }
+
+ ret = sched_setscheduler(priv->disp_thread.thread, SCHED_FIFO, &param);
+ if (ret)
+ pr_warn("display thread priority update failed: %d\n", ret);
+
/**
* this priority was found during empiric testing to have appropriate
* realtime scheduling to process display updates and interact with
@@ -544,27 +557,6 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
*/
param.sched_priority = 16;
for (i = 0; i < priv->num_crtcs; i++) {
-
- /* initialize display thread */
- priv->disp_thread[i].crtc_id = priv->crtcs[i]->base.id;
- kthread_init_worker(&priv->disp_thread[i].worker);
- priv->disp_thread[i].dev = ddev;
- priv->disp_thread[i].thread =
- kthread_run(kthread_worker_fn,
- &priv->disp_thread[i].worker,
- "crtc_commit:%d", priv->disp_thread[i].crtc_id);
- if (IS_ERR(priv->disp_thread[i].thread)) {
- DRM_DEV_ERROR(dev, "failed to create crtc_commit kthread\n");
- priv->disp_thread[i].thread = NULL;
- goto err_msm_uninit;
- }
-
- ret = sched_setscheduler(priv->disp_thread[i].thread,
- SCHED_FIFO, &param);
- if (ret)
- dev_warn(dev, "disp_thread set priority failed: %d\n",
- ret);
-
/* initialize event thread */
priv->event_thread[i].crtc_id = priv->crtcs[i]->base.id;
kthread_init_worker(&priv->event_thread[i].worker);
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 9d11f32..e81b1fa 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -197,7 +197,7 @@ struct msm_drm_private {
unsigned int num_crtcs;
struct drm_crtc *crtcs[MAX_CRTCS];

- struct msm_drm_thread disp_thread[MAX_CRTCS];
+ struct msm_drm_thread disp_thread;
struct msm_drm_thread event_thread[MAX_CRTCS];

unsigned int num_encoders;
--
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