dma-buf/sync_file: Add SET_DEADLINE ioctl

The initial purpose is for igt tests, but this would also be useful for
compositors that wait until close to vblank deadline to make decisions
about which frame to show.

The igt tests can be found at:

https://gitlab.freedesktop.org/robclark/igt-gpu-tools/-/commits/fence-deadline

v2: Clarify the timebase, add link to igt tests
v3: Use u64 value in ns to express deadline.
v4: More doc

Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230823215458.203366-3-robdclark@gmail.com

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 8aa8f8cb7071efcce29b62cf5ac3bd96c7308056..e0fd99e61a2d4fcc0f8ea3c671fb0fb2238fa332 100644 (file)
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -934,7 +934,8 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout);
  *   the GPU's devfreq to reduce frequency, when in fact the opposite is what is
  *   needed.
  *
- * To this end, deadline hint(s) can be set on a &dma_fence via &dma_fence_set_deadline.
+ * To this end, deadline hint(s) can be set on a &dma_fence via &dma_fence_set_deadline
+ * (or indirectly via userspace facing ioctls like &sync_set_deadline).
  * The deadline hint provides a way for the waiting driver, or userspace, to
  * convey an appropriate sense of urgency to the signaling driver.
  *

diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 2e9a316c596a3b3a02a950e704a265db4516b46d..d9b1c1b2a72b2c619b973db791783b28a03b8d13 100644 (file)
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -347,6 +347,22 @@ out:
        return ret;
 }
 
+static int sync_file_ioctl_set_deadline(struct sync_file *sync_file,
+                                       unsigned long arg)
+{
+       struct sync_set_deadline ts;
+
+       if (copy_from_user(&ts, (void __user *)arg, sizeof(ts)))
+               return -EFAULT;
+
+       if (ts.pad)
+               return -EINVAL;
+
+       dma_fence_set_deadline(sync_file->fence, ns_to_ktime(ts.deadline_ns));
+
+       return 0;
+}
+
 static long sync_file_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
 {
@@ -359,6 +375,9 @@ static long sync_file_ioctl(struct file *file, unsigned int cmd,
        case SYNC_IOC_FILE_INFO:
                return sync_file_ioctl_fence_info(sync_file, arg);
 
+       case SYNC_IOC_SET_DEADLINE:
+               return sync_file_ioctl_set_deadline(sync_file, arg);
+
        default:
                return -ENOTTY;
        }

diff --git a/include/uapi/linux/sync_file.h b/include/uapi/linux/sync_file.h
index ff0a931833e25f32805ff734142a6cc83f5237c8..ff1f38889dcfb48ec1217e2e1f5c1a624d74dced 100644 (file)
--- a/include/uapi/linux/sync_file.h
+++ b/include/uapi/linux/sync_file.h
@@ -76,6 +76,27 @@ struct sync_file_info {
        __u64   sync_fence_info;
 };
 
+/**
+ * struct sync_set_deadline - SYNC_IOC_SET_DEADLINE - set a deadline hint on a fence
+ * @deadline_ns: absolute time of the deadline
+ * @pad:       must be zero
+ *
+ * Allows userspace to set a deadline on a fence, see &dma_fence_set_deadline
+ *
+ * The timebase for the deadline is CLOCK_MONOTONIC (same as vblank).  For
+ * example
+ *
+ *     clock_gettime(CLOCK_MONOTONIC, &t);
+ *     deadline_ns = (t.tv_sec * 1000000000L) + t.tv_nsec + ns_until_deadline
+ */
+struct sync_set_deadline {
+       __u64   deadline_ns;
+       /* Not strictly needed for alignment but gives some possibility
+        * for future extension:
+        */
+       __u64   pad;
+};
+
 #define SYNC_IOC_MAGIC         '>'
 
 /*
@@ -87,5 +108,6 @@ struct sync_file_info {
 
 #define SYNC_IOC_MERGE         _IOWR(SYNC_IOC_MAGIC, 3, struct sync_merge_data)
 #define SYNC_IOC_FILE_INFO     _IOWR(SYNC_IOC_MAGIC, 4, struct sync_file_info)
+#define SYNC_IOC_SET_DEADLINE  _IOW(SYNC_IOC_MAGIC, 5, struct sync_set_deadline)
 
 #endif /* _UAPI_LINUX_SYNC_H */