From 7c0ed68cefdf72b1b74f59984057fff95dab52dc Mon Sep 17 00:00:00 2001
From: Matthew Bouyack <mbouyack@google.com>
Date: Thu, 30 Jun 2016 17:24:31 -0700
Subject: [PATCH] Replace the PPP workqueue with a dedicated thread
The PPP driver has little work to do but it is critical that it be
completed on time. With a dedicated thread we can use the realtime
scheduler to achieve the desired performance characteristics.
This is modeled after the behavior of the display thread in the
mdss_fb driver.
Change-Id: I599928d5f2c581718296be03b0ba14c6658fdeea
---
drivers/video/msm/mdss/mdp3_ppp.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)
diff --git a/drivers/video/msm/mdss/mdp3_ppp.c b/drivers/video/msm/mdss/mdp3_ppp.c
index d2285d76b649..a898dd75add8 100644
--- a/drivers/video/msm/mdss/mdp3_ppp.c
+++ b/drivers/video/msm/mdss/mdp3_ppp.c
@@ -101,7 +101,9 @@ struct ppp_status {
struct mutex config_ppp_mutex; /* Only one client configure register */
struct msm_fb_data_type *mfd;
- struct work_struct blit_work;
+ struct kthread_work blit_work;
+ struct kthread_worker kworker;
+ struct task_struct *blit_thread;
struct blit_req_queue req_q;
struct sw_sync_timeline *timeline;
@@ -1482,7 +1484,7 @@ static bool is_blit_optimization_possible(struct blit_req_list *req, int indx)
return status;
}
-static void mdp3_ppp_blit_wq_handler(struct work_struct *work)
+static void mdp3_ppp_blit_handler(struct kthread_work *work)
{
struct msm_fb_data_type *mfd = ppp_stat->mfd;
struct blit_req_list *req;
@@ -1650,7 +1652,7 @@ int mdp3_ppp_parse_req(void __user *p,
mdp3_ppp_req_push(req_q, req);
mutex_unlock(&ppp_stat->req_mutex);
- schedule_work(&ppp_stat->blit_work);
+ queue_kthread_work(&ppp_stat->kworker, &ppp_stat->blit_work);
if (!async) {
/* wait for release fence */
rc = sync_fence_wait(fence,
@@ -1677,6 +1679,8 @@ parse_err_1:
int mdp3_ppp_res_init(struct msm_fb_data_type *mfd)
{
+ int rc;
+ struct sched_param param = {.sched_priority = 16};
const char timeline_name[] = "mdp3_ppp";
ppp_stat = kzalloc(sizeof(struct ppp_status), GFP_KERNEL);
if (!ppp_stat) {
@@ -1693,7 +1697,22 @@ int mdp3_ppp_res_init(struct msm_fb_data_type *mfd)
ppp_stat->timeline_value = 1;
}
- INIT_WORK(&ppp_stat->blit_work, mdp3_ppp_blit_wq_handler);
+ init_kthread_worker(&ppp_stat->kworker);
+ init_kthread_work(&ppp_stat->blit_work, mdp3_ppp_blit_handler);
+ ppp_stat->blit_thread = kthread_run(kthread_worker_fn,
+ &ppp_stat->kworker,
+ "mdp3_ppp");
+
+ if (IS_ERR(ppp_stat->blit_thread)) {
+ rc = PTR_ERR(ppp_stat->blit_thread);
+ pr_err("ERROR: unable to start ppp blit thread, err = %d\n", rc);
+ ppp_stat->blit_thread = NULL;
+ return rc;
+ }
+
+ if (sched_setscheduler(ppp_stat->blit_thread, SCHED_FIFO, ¶m))
+ pr_warn("set priority failed for mdp3 blit thread\n");
+
INIT_WORK(&ppp_stat->free_bw_work, mdp3_free_bw_wq_handler);
init_completion(&ppp_stat->pop_q_comp);
mutex_init(&ppp_stat->req_mutex);
--
GitLab