Adding shutdown handler support for zocl

[saifuddin-xilinx]

Problem solved by the commit

• Adds a platform-device shutdown handler to the ZOCL DRM driver so the driver can quiesce device activity during system shutdown/reboot/kexec, reducing the chance of ongoing traffic during subsystem restart.

How problem was solved, alternative solutions (if any) and why they were rejected

• Introduces zocl_drm_platform_shutdown() to quiesce DMA, soft CUs (SCUs), and AIE workqueues during shutdown.
  Registers the new shutdown callback via .shutdown = zocl_drm_platform_shutdown in the platform_driver.

Bug / issue (if any) fixed, which PR introduced the bug, how it was discovered

• VITIS-15710

Risks (if any) associated the changes in the commit

What has been tested and how, request additional testing if necessary

Documentation impact (if any)

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 3 comments.

Suppressed comments (1)

src/runtime_src/core/edge/drm/zocl/common/zocl_drv.c:1655

• Same as the remove() path: clearing zdev->zdev_dma_chan without synchronizing with the lazy DMA channel acquisition path can allow other threads to request and store a new DMA channel while shutdown teardown is in progress. That can leak channels and undermine the goal of quiescing DMA during shutdown. Please coordinate this with the DMA acquisition/use sites via a shared lock and/or a teardown flag that prevents new channel requests once shutdown begins.

		/* Prevent new users from reusing the channel during shutdown */
		zdev->zdev_dma_chan = NULL;
		/* Ensure any in-flight transactions are stopped before releasing */
		dmaengine_terminate_sync(chan);
		dma_release_channel(chan);

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

Suppressed comments (1)

src/runtime_src/core/edge/drm/zocl/common/zocl_drv.c:1563

• DMA channel teardown in .remove updates zdev->zdev_dma_chan without any synchronization. Since the DRM device is still registered until later in remove(), an ioctl path could race here (e.g., allocate/reuse the channel after it was set to NULL, leading to leaks or use-after-release). Consider serializing access with mm_lock and capturing the pointer under the lock before terminating/releasing the channel.

	if (zdev->zdev_dma_chan) {
		struct dma_chan *chan = zdev->zdev_dma_chan;
		/* Prevent new users from reusing the channel during teardown */
		zdev->zdev_dma_chan = NULL;
		/* Ensure any in-flight transactions are stopped before releasing */

[saifuddin-xilinx]

retest this please

[saifuddin-xilinx]

retest this please