drm/vc4: Use DMA Resv to implement VC4 wait BO IOCTL

Since the BOs used by VC4 have DMA Reservation Objects attached to
them, waiting for seqnos to check BO availability is unnecessary.
Instead, `drm_gem_dma_resv_wait()` can be used.

Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Melissa Wen <mwen@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241220134204.634577-3-mcanal@igalia.com

diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index 1021f45cb53cc498613fd8c7549c6bcdbc77f526..de7be9942c1342ea55538cf51dd0e9b8d6a4ac7d 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -1020,8 +1020,10 @@ vc4_wait_bo_ioctl(struct drm_device *dev, void *data,
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        int ret;
        struct drm_vc4_wait_bo *args = data;
-       struct drm_gem_object *gem_obj;
-       struct vc4_bo *bo;
+       unsigned long timeout_jiffies =
+               usecs_to_jiffies(div_u64(args->timeout_ns, 1000));
+       ktime_t start = ktime_get();
+       u64 delta_ns;
 
        if (WARN_ON_ONCE(vc4->gen > VC4_GEN_4))
                return -ENODEV;
@@ -1029,17 +1031,18 @@ vc4_wait_bo_ioctl(struct drm_device *dev, void *data,
        if (args->pad != 0)
                return -EINVAL;
 
-       gem_obj = drm_gem_object_lookup(file_priv, args->handle);
-       if (!gem_obj) {
-               DRM_DEBUG("Failed to look up GEM BO %d\n", args->handle);
-               return -EINVAL;
-       }
-       bo = to_vc4_bo(gem_obj);
+       ret = drm_gem_dma_resv_wait(file_priv, args->handle,
+                                   true, timeout_jiffies);
 
-       ret = vc4_wait_for_seqno_ioctl_helper(dev, bo->seqno,
-                                             &args->timeout_ns);
+       /* Decrement the user's timeout, in case we got interrupted
+        * such that the ioctl will be restarted.
+        */
+       delta_ns = ktime_to_ns(ktime_sub(ktime_get(), start));
+       if (delta_ns < args->timeout_ns)
+               args->timeout_ns -= delta_ns;
+       else
+               args->timeout_ns = 0;
 
-       drm_gem_object_put(gem_obj);
        return ret;
 }