drm/vc4: Optimise vc4_hvs_dlist_free_work to only read frcnt and active once

vc4_hvs_dlist_free_work was iterating through the list of stale
dlist entries and reading the frame count and active flags from
the hardware for each one.

Read the frame count and active flags once, and then use the
cached value in the loop.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
index 8872a55..e4466d8 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -855,14 +855,19 @@ static void vc4_hvs_dlist_free_work(struct work_struct *work)
        struct vc4_hvs *hvs = container_of(work, struct vc4_hvs, free_dlist_work);
        struct vc4_hvs_dlist_allocation *cur, *next;
        unsigned long flags;
+       bool active[3];
+       u8 frcnt[3];
+       int i;
+
 
        spin_lock_irqsave(&hvs->mm_lock, flags);
+       for (i = 0; i < 3; i++) {
+               frcnt[i] = vc4_hvs_get_fifo_frame_count(hvs, i);
+               active[i] = vc4_hvs_check_channel_active(hvs, i);
+       }
        list_for_each_entry_safe(cur, next, &hvs->stale_dlist_entries, node) {
-               u8 frcnt;
-
-               frcnt = vc4_hvs_get_fifo_frame_count(hvs, cur->channel);
-               if (vc4_hvs_check_channel_active(hvs, cur->channel) &&
-                   !vc4_hvs_frcnt_lte(cur->target_frame_count, frcnt))
+               if (active[cur->channel] &&
+                   !vc4_hvs_frcnt_lte(cur->target_frame_count, frcnt[cur->channel]))
                        continue;
 
                vc4_hvs_free_dlist_entry_locked(hvs, cur);