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| author | Mika Kahola <mika.kahola@intel.com> | 2020-05-06 15:08:27 +0300 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-05-08 12:12:58 +0200 |
| commit | 50b6f619a099af6dfe06e958bfa08d46440ea788 (patch) | |
| tree | be819d1972f4b4a3aca810cb8ec33d6e64e20f41 /include/uapi/drm | |
| parent | d6ddbd5c97d1b9156646ac5c42b8851edd664ee2 (diff) | |
| download | linux-50b6f619a099af6dfe06e958bfa08d46440ea788.tar.bz2 | |
uapi/drm/drm_fourcc.h: Note on platform specificity for format modifiers
Make an additional note on DRM format modifiers for x and y tiling. These
format modifiers are defined for BDW+ platforms and therefore definition
is not valid for older gens. This is due to address swizzling for tiled
surfaces is no longer used. For newer platforms main memory controller has
a more effective address swizzling algorithm.
v2: Rephrase comment (Daniel)
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200506120827.12250-1-mika.kahola@intel.com
Diffstat (limited to 'include/uapi/drm')
| -rw-r--r-- | include/uapi/drm/drm_fourcc.h | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h index 8bc0b31597d8..9e488d10f8b4 100644 --- a/include/uapi/drm/drm_fourcc.h +++ b/include/uapi/drm/drm_fourcc.h @@ -354,9 +354,12 @@ extern "C" { * a platform-dependent stride. On top of that the memory can apply * platform-depending swizzling of some higher address bits into bit6. * - * This format is highly platforms specific and not useful for cross-driver - * sharing. It exists since on a given platform it does uniquely identify the - * layout in a simple way for i915-specific userspace. + * Note that this layout is only accurate on intel gen 8+ or valleyview chipsets. + * On earlier platforms the is highly platforms specific and not useful for + * cross-driver sharing. It exists since on a given platform it does uniquely + * identify the layout in a simple way for i915-specific userspace, which + * facilitated conversion of userspace to modifiers. Additionally the exact + * format on some really old platforms is not known. */ #define I915_FORMAT_MOD_X_TILED fourcc_mod_code(INTEL, 1) @@ -369,9 +372,12 @@ extern "C" { * memory can apply platform-depending swizzling of some higher address bits * into bit6. * - * This format is highly platforms specific and not useful for cross-driver - * sharing. It exists since on a given platform it does uniquely identify the - * layout in a simple way for i915-specific userspace. + * Note that this layout is only accurate on intel gen 8+ or valleyview chipsets. + * On earlier platforms the is highly platforms specific and not useful for + * cross-driver sharing. It exists since on a given platform it does uniquely + * identify the layout in a simple way for i915-specific userspace, which + * facilitated conversion of userspace to modifiers. Additionally the exact + * format on some really old platforms is not known. */ #define I915_FORMAT_MOD_Y_TILED fourcc_mod_code(INTEL, 2) |