On Fri, 06 Feb 2026 10:32:38 +0100
Philipp Stanner [off-list ref] wrote:

On Thu, 2026-02-05 at 13:16 +0000, Gary Guo wrote:

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On Thu Feb 5, 2026 at 10:16 AM GMT, Boris Brezillon wrote:  

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On Tue,  3 Feb 2026 09:14:01 +0100
Philipp Stanner [off-list ref] wrote:
  

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+#[pin_data]
+pub struct DmaFence<T> {
+    /// The actual dma_fence passed to C.
+    #[pin]
+    inner: Opaque<bindings::dma_fence>,
+    /// User data.
+    #[pin]
+    data: T,  

A DmaFence is a cross-device synchronization mechanism that can (and
will)
  

I'm not questioning the truth behind this statement. They are designed
to do that. But is that actually being done, currently? I recently
found that the get_driver_name() callback intended to inform the
consumer of a fence about who actually issued the fence is only ever
used by i915.

It's also used by the dma-buf layer to expose info about dma-bufs
through debugfs (see dma_{fence,resv}_describe() and
dma_buf_debug_show()), meaning all GPU drivers adding their fences to
the dma_resv of an imported/exported buffer object should expect to
have their ::get_{driver,timeline}_name() implementation called.