Fix a bug in the metal implemtation of col2im1d. (huggingface#2284)

candle-core/src/metal_backend/mod.rs

@@ -848,7 +848,6 @@ impl BackendStorage for MetalStorage {
  .device
  .new_buffer(dst_el, self.dtype, "conv_transpose1d")?;
 
- let command_buffer = self.device.command_buffer()?;
  let name = match self.dtype {
  DType::F32 => "col2im1d_f32",
  DType::U32 => "col2im1d_u32",
@@ -869,6 +868,12 @@ impl BackendStorage for MetalStorage {
  &kernel_l_mm,
  )?
  };
+ // It is important for the command buffer to be obtained *after* the matmul
+ // kernel has run, otherwise we might use a command-buffer that has been commited
+ // already resulting in the following error.
+ // _status < MTLCommandBufferStatusCommitted >
+ // -[IOGPUMetalCommandBuffer setCurrentCommandEncoder:]
+ let command_buffer = self.device.command_buffer()?;
  candle_metal_kernels::call_col2im1d(
  &self.device.device,
  &command_buffer,