MLK-16536-16 video: fbdev: dcss: change 'refcount' to 'struct kref' type

Use 'struct kref' type for 'refcount' field instead of
'atomic_t' to take advantage of 'kref_*()' interface
series. The benefit to do so can improve the defered
cfifo flush performance, since this defered flush does
not need to wait to be done until next vsync happens.

Signed-off-by: Fancy Fang <chen.fang@nxp.com>
Reviewed-by: Robby Cai <robby.cai@nxp.com>

diff --git a/drivers/video/fbdev/mxc/imx_dcss.c b/drivers/video/fbdev/mxc/imx_dcss.c
index 290d42e..b065956 100644 (file)
--- a/drivers/video/fbdev/mxc/imx_dcss.c
+++ b/drivers/video/fbdev/mxc/imx_dcss.c
@@ -262,7 +262,7 @@ struct vsync_info {
 
 struct ctxld_commit {
        struct list_head list;
-       atomic_t refcount;
+       struct kref refcount;
        struct work_struct work;
        void *data;
        uint32_t sb_data_len;
@@ -540,6 +540,8 @@ static int vcount_compare(unsigned long vcount,
                          struct vsync_info *vinfo);
 static int dcss_wait_for_vsync(unsigned long crtc,
                               struct dcss_info *info);
+static void flush_cfifo(struct ctxld_fifo *cfifo,
+                       struct work_struct *work);
 
 static struct fb_ops dcss_ops = {
        .owner = THIS_MODULE,
@@ -2351,8 +2353,8 @@ static struct ctxld_commit *alloc_cc(struct dcss_info *info)
 
        INIT_LIST_HEAD(&cc->list);
        INIT_WORK(&cc->work, dcss_ctxld_config);
+       kref_init(&cc->refcount);
        cc->data = info;
-       atomic_set(&cc->refcount, 0);
 
        return cc;
 }
@@ -2386,7 +2388,7 @@ static struct ctxld_commit *obtain_cc(int ch_id, struct dcss_info *info)
                cc = list_first_entry(&cfifo->ctxld_list,
                                      struct ctxld_commit,
                                      list);
-               atomic_inc(&cc->refcount);
+               kref_get(&cc->refcount);
        }
 
        spin_unlock_irqrestore(&vinfo->vwait.lock, irqflags);
@@ -2406,7 +2408,7 @@ static struct ctxld_commit *obtain_cc(int ch_id, struct dcss_info *info)
                                              struct ctxld_commit,
                                              list);
                }
-               atomic_inc(&cc->refcount);
+               kref_get(&cc->refcount);
 
                spin_unlock_irqrestore(&vinfo->vwait.lock, irqflags);
        }
@@ -2414,11 +2416,42 @@ static struct ctxld_commit *obtain_cc(int ch_id, struct dcss_info *info)
        return cc;
 }
 
-static void release_cc(struct ctxld_commit *cc)
+static void release_cc(struct kref *kref)
 {
-       WARN_ON(!atomic_read(&cc->refcount));
+       unsigned long irqflags;
+       struct ctxld_commit *cc;
+       struct dcss_info *info;
+       struct vsync_info *vinfo;
+       struct ctxld_fifo *cfifo;
+
+       cc = container_of(kref, struct ctxld_commit, refcount);
+       info  = (struct dcss_info *)cc->data;
+       vinfo = &info->vinfo;
+       cfifo = &info->cfifo;
 
-       atomic_dec(&cc->refcount);
+       spin_lock_irqsave(&vinfo->vwait.lock, irqflags);
+
+       list_del(&cc->list);
+       flush_cfifo(cfifo, &cc->work);
+
+       spin_unlock_irqrestore(&vinfo->vwait.lock, irqflags);
+}
+
+/**
+ * Only be called when 'vwait.lock' is hold
+ */
+static void release_cc_locked(struct kref *kref)
+{
+       struct ctxld_commit *cc;
+       struct dcss_info *info;
+       struct ctxld_fifo *cfifo;
+
+       cc = container_of(kref, struct ctxld_commit, refcount);
+       info  = (struct dcss_info *)cc->data;
+       cfifo = &info->cfifo;
+
+       list_del(&cc->list);
+       flush_cfifo(cfifo, &cc->work);
 }
 
 static void flush_cfifo(struct ctxld_fifo *cfifo,
@@ -2485,7 +2518,7 @@ static int commit_cfifo(uint32_t channel,
 
        if (unlikely(atomic_read(&info->flush) == 1)) {
                /* cancel this commit and restart it later */
-               release_cc(cc);
+               kref_put(&cc->refcount, release_cc);
 
                wait_event_interruptible_exclusive_locked(cfifo->cqueue,
                                                atomic_read(&info->flush));
@@ -2502,7 +2535,7 @@ static int commit_cfifo(uint32_t channel,
                spin_unlock(&cfifo->cqueue.lock);
 
                /* cancel this commit and restart it later */
-               release_cc(cc);
+               kref_put(&cc->refcount, release_cc);
 
                /* Wait fifo flush empty to avoid fifo wrap */
                finish_cfifo(cfifo);
@@ -2765,7 +2798,7 @@ restart:
        if (ret == -ERESTART)
                goto restart;
 
-       release_cc(cc);
+       kref_put(&cc->refcount, release_cc);
 #endif
 
        goto out;
@@ -2849,7 +2882,7 @@ restart:
        if (ret == -ERESTART)
                goto restart;
 
-       release_cc(cc);
+       kref_put(&cc->refcount, release_cc);
 #endif
 
        cinfo->blank = blank;
@@ -2920,7 +2953,7 @@ restart:
        if (ret == -ERESTART)
                goto restart;
 
-       release_cc(cc);
+       kref_put(&cc->refcount, release_cc);
 #endif
 
        goto out;
@@ -3031,6 +3064,7 @@ static void ctxld_irq_clear(struct dcss_info *info)
 
 static irqreturn_t dcss_irq_handler(int irq, void *dev_id)
 {
+       int ret;
        struct irq_desc *desc;
        uint32_t irq_status;
        unsigned long irqflags;
@@ -3062,18 +3096,19 @@ static irqreturn_t dcss_irq_handler(int irq, void *dev_id)
 
                spin_lock_irqsave(&info->vinfo.vwait.lock, irqflags);
 
+               /* unblock new commits */
                info->vinfo.vcount++;
+
                if (!list_empty(&cfifo->ctxld_list)) {
                        cc = list_first_entry(&cfifo->ctxld_list,
                                              struct ctxld_commit,
                                              list);
-                       /* defer cfifo flush to next frame window */
-                       if (atomic_read(&cc->refcount))
+
+                       ret = kref_put(&cc->refcount, release_cc_locked);
+
+                       /* 'cc' can not be released */
+                       if (!ret)
                                defer_flush_cfifo(cfifo);
-                       else {
-                               list_del(&cc->list);
-                               flush_cfifo(cfifo, &cc->work);
-                       }
                }
 
                spin_unlock_irqrestore(&info->vinfo.vwait.lock, irqflags);