Merge tag 'drm-misc-next-2021-07-16' of git://anongit.freedesktop.org/drm/drm-misc into drm-next

drm-misc-next for v5.15:

UAPI Changes:

Cross-subsystem Changes:
- udmabuf: Add support for mapping hugepages
- Add dma-buf stats to sysfs.
- Assorted fixes to fbdev/omap2.
- dma-buf: Document DMA_BUF_IOCTL_SYNC
- Improve dma-buf non-dynamic exporter expectations better.
- Add module parameters for dma-buf size and list limit.
- Add HDMI codec support to vc4, to replace vc4's own codec.
- Document dma-buf implicit fencing rules.
- dma_resv_test_signaled test_all handling.

Core Changes:
- Extract i915's eDP backlight code into DRM helpers.
- Assorted docbook updates.
- Rework drm_dp_aux documentation.
- Add support for the DP aux bus.
- Shrink dma-fence-chain slightly.
- Add alloc/free helpers for dma-fence-chain.
- Assorted fixes to TTM., drm/of, bridge
- drm_gem_plane_helper_prepare/cleanup_fb is now the default for gem drivers.
- Small fix for scheduler completion.
- Remove use of drm_device.irq_enabled.
- Print the driver name to dmesg when registering framebuffer.
- Export drm/gem's shadow plane handling, and use it in vkms.
- Assorted small fixes.

Driver Changes:
- Add eDP backlight to nouveau.
- Assorted fixes and cleanups to nouveau, panfrost, vmwgfx, anx7625,
  amdgpu, gma500, radeon, mgag200, vgem, vc4, vkms, omapdrm.
- Add support for Samsung DB7430, Samsung ATNA33XC20, EDT ETMV570G2DHU,
  EDT ETM0350G0DH6, Innolux EJ030NA panels.
- Fix some simple pannels missing bus_format and connector types.
- Add mks-guest-stats instrumentation support to vmwgfx.
- Merge i915-ttm topic branch.
- Make s6e63m0 panel use Mipi-DBI helpers.
- Add detect() supoprt for AST.
- Use interrupts for hotplug on vc4.
- vmwgfx is now moved to drm-misc-next, as sroland is no longer a maintainer for now.
- vmwgfx now uses copies of vmware's internal device headers.
- Slowly convert ti-sn65dsi83 over to atomic.
- Rework amdgpu dma-resv handling.
- Fix virtio fencing for planes.
- Ensure amdgpu can always evict to SYSTEM.
- Many drivers fixed for implicit fencing rules.
- Set default prepare/cleanup fb for tiny, vram and simple helpers too.
- Rework panfrost gpu reset and related serialization.
- Update VKMS todo list.
- Make bochs a tiny gpu driver, and use vram helper.
- Use linux irq interfaces instead of drm_irq in some drivers.
- Add support for Raspberry Pi Pico to GUD.

Signed-off-by: Dave Airlie <airlied@redhat.com>

# gpg: Signature made Fri 16 Jul 2021 21:06:04 AEST
# gpg:                using RSA key B97BD6A80CAC4981091AE547FE558C72A67013C3
# gpg: Good signature from "Maarten Lankhorst <maarten.lankhorst@linux.intel.com>" [expired]
# gpg:                 aka "Maarten Lankhorst <maarten@debian.org>" [expired]
# gpg:                 aka "Maarten Lankhorst <maarten.lankhorst@canonical.com>" [expired]
# gpg: Note: This key has expired!
# Primary key fingerprint: B97B D6A8 0CAC 4981 091A  E547 FE55 8C72 A670 13C3
From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/444811c3-cbec-e9d5-9a6b-9632eda7962a@linux.intel.com

1 files changed, 49 insertions, 1 deletions

diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
index 7f30393b92c3..8e4a2ca0bcbf 100644
--- a/include/uapi/linux/dma-buf.h
+++ b/include/uapi/linux/dma-buf.h
@@ -22,8 +22,56 @@
 
 #include <linux/types.h>
 
-/* begin/end dma-buf functions used for userspace mmap. */
+/**
+ * struct dma_buf_sync - Synchronize with CPU access.
+ *
+ * When a DMA buffer is accessed from the CPU via mmap, it is not always
+ * possible to guarantee coherency between the CPU-visible map and underlying
+ * memory.  To manage coherency, DMA_BUF_IOCTL_SYNC must be used to bracket
+ * any CPU access to give the kernel the chance to shuffle memory around if
+ * needed.
+ *
+ * Prior to accessing the map, the client must call DMA_BUF_IOCTL_SYNC
+ * with DMA_BUF_SYNC_START and the appropriate read/write flags.  Once the
+ * access is complete, the client should call DMA_BUF_IOCTL_SYNC with
+ * DMA_BUF_SYNC_END and the same read/write flags.
+ *
+ * The synchronization provided via DMA_BUF_IOCTL_SYNC only provides cache
+ * coherency.  It does not prevent other processes or devices from
+ * accessing the memory at the same time.  If synchronization with a GPU or
+ * other device driver is required, it is the client's responsibility to
+ * wait for buffer to be ready for reading or writing before calling this
+ * ioctl with DMA_BUF_SYNC_START.  Likewise, the client must ensure that
+ * follow-up work is not submitted to GPU or other device driver until
+ * after this ioctl has been called with DMA_BUF_SYNC_END?
+ *
+ * If the driver or API with which the client is interacting uses implicit
+ * synchronization, waiting for prior work to complete can be done via
+ * poll() on the DMA buffer file descriptor.  If the driver or API requires
+ * explicit synchronization, the client may have to wait on a sync_file or
+ * other synchronization primitive outside the scope of the DMA buffer API.
+ */
 struct dma_buf_sync {
+	/**
+	 * @flags: Set of access flags
+	 *
+	 * DMA_BUF_SYNC_START:
+	 *     Indicates the start of a map access session.
+	 *
+	 * DMA_BUF_SYNC_END:
+	 *     Indicates the end of a map access session.
+	 *
+	 * DMA_BUF_SYNC_READ:
+	 *     Indicates that the mapped DMA buffer will be read by the
+	 *     client via the CPU map.
+	 *
+	 * DMA_BUF_SYNC_WRITE:
+	 *     Indicates that the mapped DMA buffer will be written by the
+	 *     client via the CPU map.
+	 *
+	 * DMA_BUF_SYNC_RW:
+	 *     An alias for DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE.
+	 */
 	__u64 flags;
 };