diff options
| author | Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com> | 2021-06-04 09:00:11 -0400 |
|---|---|---|
| committer | Steven Price <steven.price@arm.com> | 2021-06-04 16:16:04 +0100 |
| commit | 3e2926f8753dac1ded56c8ef3e91f56ee763dafd (patch) | |
| tree | 87dceeacea1e1bae6dafe8aa8a088404446d20d3 /include | |
| parent | cb1c81467af355829a4a9d8fa3f92ffab355d93c (diff) | |
| download | linux-3e2926f8753dac1ded56c8ef3e91f56ee763dafd.tar.bz2 | |
drm/panfrost: Add AFBC_FEATURES parameter
The value of the AFBC_FEATURES register is required by userspace to
determine AFBC support on Bifrost. A user on our IRC channel (#panfrost)
reported a workload that raised a fault on one system's Mali G31 but
worked flawlessly with another system's Mali G31. We determined the
cause to be missing AFBC support on one vendor's Mali implementation --
it turns out AFBC is optional on Bifrost!
Whether AFBC is supported or not is exposed in the AFBC_FEATURES
register on Bifrost, which reads back as 0 on Midgard. A zero value
indicates AFBC is fully supported, provided the architecture itself
supports AFBC, allowing backwards-compatibility with Midgard. Bits 0 and
15 indicate that AFBC support is absent for texturing and rendering
respectively.
The user experiencing the fault reports that AFBC_FEATURES reads back
0x10001 on their system, confirming the architectural lack of AFBC.
Userspace needs this parameter to know to disable AFBC on that
chip, and perhaps others.
v2: Fix typo from copy-paste fail.
v3: Bump the UABI version. This commit was cherry-picked from another
series so chalking this up to a rebase fail.
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210604130011.3203-1-alyssa.rosenzweig@collabora.com
Diffstat (limited to 'include')
| -rw-r--r-- | include/uapi/drm/panfrost_drm.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/drm/panfrost_drm.h b/include/uapi/drm/panfrost_drm.h index ec19db1eead8..061e700dd06c 100644 --- a/include/uapi/drm/panfrost_drm.h +++ b/include/uapi/drm/panfrost_drm.h @@ -171,6 +171,7 @@ enum drm_panfrost_param { DRM_PANFROST_PARAM_JS_FEATURES15, DRM_PANFROST_PARAM_NR_CORE_GROUPS, DRM_PANFROST_PARAM_THREAD_TLS_ALLOC, + DRM_PANFROST_PARAM_AFBC_FEATURES, }; struct drm_panfrost_get_param { |