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authorDave Airlie <airlied@redhat.com>2021-06-02 14:04:29 +1000
committerDave Airlie <airlied@redhat.com>2021-06-02 14:15:54 +1000
commitccd1950c2f7e38ae45aeefb99a08b39407cd6c63 (patch)
tree1fe82742fce2934ec5720e7bc265dabc8c015656 /Documentation/gpu
parent43ed3c6c786d996a264fcde68dbb36df6f03b965 (diff)
parent5b26d57fdb499c2363f3d895ef008e73ec02eb9b (diff)
Merge tag 'drm-intel-gt-next-2021-05-28' of git://anongit.freedesktop.org/drm/drm-intel into drm-next
UAPI Changes: - Add reworked uAPI for DG1 behind CONFIG_BROKEN (Matt A, Abdiel) Driver Changes: - Fix for Gitlab issues #3293 and #3450: Avoid kernel crash on older L-shape memory machines - Add Wa_14010733141 (VDBox SFC reset) for Gen11+ (Aditya) - Fix crash in auto_retire active retire callback due to misalignment (Stephane) - Fix overlay active retire callback alignment (Tvrtko) - Eliminate need to align active retire callbacks (Matt A, Ville, Daniel) - Program FF_MODE2 tuning value for all Gen12 platforms (Caz) - Add Wa_14011060649 for TGL,RKL,DG1 and ADLS (Swathi) - Create stolen memory region from local memory on DG1 (CQ) - Place PD in LMEM on dGFX (Matt A) - Use WC when default state object is allocated in LMEM (Venkata) - Determine the coherent map type based on object location (Venkata) - Use lmem physical addresses for fb_mmap() on discrete (Mohammed) - Bypass aperture on fbdev when LMEM is available (Anusha) - Return error value when displayable BO not in LMEM for dGFX (Mohammed) - Do release kernel context if breadcrumb measure fails (Janusz) - Hide modparams for compiled-out features (Tvrtko) - Apply Wa_22010271021 for all Gen11 platforms (Caz) - Fix unlikely ref count race in arming the watchdog timer (Tvrtko) - Check actual RC6 enable status in PMU (Tvrtko) - Fix a double free in gen8_preallocate_top_level_pdp (Lv) - Use trylock in shrinker for GGTT on BSW VT-d and BXT (Maarten) - Remove erroneous i915_is_ggtt check for I915_GEM_OBJECT_UNBIND_VM_TRYLOCK (Maarten) - Convert uAPI headers to real kerneldoc (Matt A) - Clean up kerneldoc warnings headers (Matt A, Maarten) - Fail driver if LMEM training failed (Matt R) - Avoid div-by-zero on Gen2 (Ville) - Read C0DRB3/C1DRB3 as 16 bits again and add _BW suffix (Ville) - Remove reference to struct drm_device.pdev (Thomas) - Increase separation between GuC and execlists code (Chris, Matt B) - Use might_alloc() (Bernard) - Split DGFX_FEATURES from GEN12_FEATURES (Lucas) - Deduplicate Wa_22010271021 programming on (Jose) - Drop duplicate WaDisable4x2SubspanOptimization:hsw (Tvrtko) - Selftest improvements (Chris, Hsin-Yi, Tvrtko) - Shuffle around init_memory_region for stolen (Matt) - Typo fixes (wengjianfeng) [airlied: fix conflict with fixes in i915_active.c] Signed-off-by: Dave Airlie <airlied@redhat.com> From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/YLCbBR22BsQ/dpJB@jlahtine-mobl.ger.corp.intel.com
Diffstat (limited to 'Documentation/gpu')
-rw-r--r--Documentation/gpu/driver-uapi.rst8
-rw-r--r--Documentation/gpu/index.rst1
-rw-r--r--Documentation/gpu/rfc/i915_gem_lmem.rst131
-rw-r--r--Documentation/gpu/rfc/index.rst4
4 files changed, 144 insertions, 0 deletions
diff --git a/Documentation/gpu/driver-uapi.rst b/Documentation/gpu/driver-uapi.rst
new file mode 100644
index 000000000000..4411e6919a3d
--- /dev/null
+++ b/Documentation/gpu/driver-uapi.rst
@@ -0,0 +1,8 @@
+===============
+DRM Driver uAPI
+===============
+
+drm/i915 uAPI
+=============
+
+.. kernel-doc:: include/uapi/drm/i915_drm.h
diff --git a/Documentation/gpu/index.rst b/Documentation/gpu/index.rst
index ec4bc72438e4..b9c1214d8f23 100644
--- a/Documentation/gpu/index.rst
+++ b/Documentation/gpu/index.rst
@@ -10,6 +10,7 @@ Linux GPU Driver Developer's Guide
drm-kms
drm-kms-helpers
drm-uapi
+ driver-uapi
drm-client
drivers
backlight
diff --git a/Documentation/gpu/rfc/i915_gem_lmem.rst b/Documentation/gpu/rfc/i915_gem_lmem.rst
new file mode 100644
index 000000000000..675ba8620d66
--- /dev/null
+++ b/Documentation/gpu/rfc/i915_gem_lmem.rst
@@ -0,0 +1,131 @@
+=========================
+I915 DG1/LMEM RFC Section
+=========================
+
+Upstream plan
+=============
+For upstream the overall plan for landing all the DG1 stuff and turning it for
+real, with all the uAPI bits is:
+
+* Merge basic HW enabling of DG1(still without pciid)
+* Merge the uAPI bits behind special CONFIG_BROKEN(or so) flag
+ * At this point we can still make changes, but importantly this lets us
+ start running IGTs which can utilize local-memory in CI
+* Convert over to TTM, make sure it all keeps working. Some of the work items:
+ * TTM shrinker for discrete
+ * dma_resv_lockitem for full dma_resv_lock, i.e not just trylock
+ * Use TTM CPU pagefault handler
+ * Route shmem backend over to TTM SYSTEM for discrete
+ * TTM purgeable object support
+ * Move i915 buddy allocator over to TTM
+ * MMAP ioctl mode(see `I915 MMAP`_)
+ * SET/GET ioctl caching(see `I915 SET/GET CACHING`_)
+* Send RFC(with mesa-dev on cc) for final sign off on the uAPI
+* Add pciid for DG1 and turn on uAPI for real
+
+New object placement and region query uAPI
+==========================================
+Starting from DG1 we need to give userspace the ability to allocate buffers from
+device local-memory. Currently the driver supports gem_create, which can place
+buffers in system memory via shmem, and the usual assortment of other
+interfaces, like dumb buffers and userptr.
+
+To support this new capability, while also providing a uAPI which will work
+beyond just DG1, we propose to offer three new bits of uAPI:
+
+DRM_I915_QUERY_MEMORY_REGIONS
+-----------------------------
+New query ID which allows userspace to discover the list of supported memory
+regions(like system-memory and local-memory) for a given device. We identify
+each region with a class and instance pair, which should be unique. The class
+here would be DEVICE or SYSTEM, and the instance would be zero, on platforms
+like DG1.
+
+Side note: The class/instance design is borrowed from our existing engine uAPI,
+where we describe every physical engine in terms of its class, and the
+particular instance, since we can have more than one per class.
+
+In the future we also want to expose more information which can further
+describe the capabilities of a region.
+
+.. kernel-doc:: include/uapi/drm/i915_drm.h
+ :functions: drm_i915_gem_memory_class drm_i915_gem_memory_class_instance drm_i915_memory_region_info drm_i915_query_memory_regions
+
+GEM_CREATE_EXT
+--------------
+New ioctl which is basically just gem_create but now allows userspace to provide
+a chain of possible extensions. Note that if we don't provide any extensions and
+set flags=0 then we get the exact same behaviour as gem_create.
+
+Side note: We also need to support PXP[1] in the near future, which is also
+applicable to integrated platforms, and adds its own gem_create_ext extension,
+which basically lets userspace mark a buffer as "protected".
+
+.. kernel-doc:: include/uapi/drm/i915_drm.h
+ :functions: drm_i915_gem_create_ext
+
+I915_GEM_CREATE_EXT_MEMORY_REGIONS
+----------------------------------
+Implemented as an extension for gem_create_ext, we would now allow userspace to
+optionally provide an immutable list of preferred placements at creation time,
+in priority order, for a given buffer object. For the placements we expect
+them each to use the class/instance encoding, as per the output of the regions
+query. Having the list in priority order will be useful in the future when
+placing an object, say during eviction.
+
+.. kernel-doc:: include/uapi/drm/i915_drm.h
+ :functions: drm_i915_gem_create_ext_memory_regions
+
+One fair criticism here is that this seems a little over-engineered[2]. If we
+just consider DG1 then yes, a simple gem_create.flags or something is totally
+all that's needed to tell the kernel to allocate the buffer in local-memory or
+whatever. However looking to the future we need uAPI which can also support
+upcoming Xe HP multi-tile architecture in a sane way, where there can be
+multiple local-memory instances for a given device, and so using both class and
+instance in our uAPI to describe regions is desirable, although specifically
+for DG1 it's uninteresting, since we only have a single local-memory instance.
+
+Existing uAPI issues
+====================
+Some potential issues we still need to resolve.
+
+I915 MMAP
+---------
+In i915 there are multiple ways to MMAP GEM object, including mapping the same
+object using different mapping types(WC vs WB), i.e multiple active mmaps per
+object. TTM expects one MMAP at most for the lifetime of the object. If it
+turns out that we have to backpedal here, there might be some potential
+userspace fallout.
+
+I915 SET/GET CACHING
+--------------------
+In i915 we have set/get_caching ioctl. TTM doesn't let us to change this, but
+DG1 doesn't support non-snooped pcie transactions, so we can just always
+allocate as WB for smem-only buffers. If/when our hw gains support for
+non-snooped pcie transactions then we must fix this mode at allocation time as
+a new GEM extension.
+
+This is related to the mmap problem, because in general (meaning, when we're
+not running on intel cpus) the cpu mmap must not, ever, be inconsistent with
+allocation mode.
+
+Possible idea is to let the kernel picks the mmap mode for userspace from the
+following table:
+
+smem-only: WB. Userspace does not need to call clflush.
+
+smem+lmem: We only ever allow a single mode, so simply allocate this as uncached
+memory, and always give userspace a WC mapping. GPU still does snooped access
+here(assuming we can't turn it off like on DG1), which is a bit inefficient.
+
+lmem only: always WC
+
+This means on discrete you only get a single mmap mode, all others must be
+rejected. That's probably going to be a new default mode or something like
+that.
+
+Links
+=====
+[1] https://patchwork.freedesktop.org/series/86798/
+
+[2] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5599#note_553791
diff --git a/Documentation/gpu/rfc/index.rst b/Documentation/gpu/rfc/index.rst
index a8621f7dab8b..05670442ca1b 100644
--- a/Documentation/gpu/rfc/index.rst
+++ b/Documentation/gpu/rfc/index.rst
@@ -15,3 +15,7 @@ host such documentation:
* Once the code has landed move all the documentation to the right places in
the main core, helper or driver sections.
+
+.. toctree::
+
+ i915_gem_lmem.rst