kernel/linux.git/include/drm/drm_fixed.h, branch v6.19.11

drm: Add helper for conversion from signed-magnitude

2025-11-26T21:16:13+00:00

CTM values are defined as signed-magnitude values. Add a helper that converts from CTM signed-magnitude fixed point value to the twos-complement value used by drm_fixed. Reviewed-by: Sebastian Wick Reviewed-by: Louis Chauvet Signed-off-by: Harry Wentland Reviewed-by: Daniel Stone Reviewed-by: Melissa Wen Signed-off-by: Simon Ser Link: https://patch.msgid.link/20251115000237.3561250-2-alex.hung@amd.com

drm: fixed: Don't use "proxy" headers

2024-08-13T09:13:45+00:00

Update header inclusions to follow IWYU (Include What You Use) principle. Signed-off-by: Andy Shevchenko Reviewed-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/20240422143338.2026791-1-andriy.shevchenko@linux.intel.com Signed-off-by: Jani Nikula

drm: Add helpers for q4 fixed point values

2024-07-03T15:05:12+00:00

Add helpers to convert between q4 fixed point and integer/fraction values. Also add the format/argument macros required to printk q4 fixed point variables. The q4 notation is based on the short variant described by https://en.wikipedia.org/wiki/Q_(number_format) where only the number of fraction bits in the fixed point value are defined, while the full size is deducted from the container type, that is the size of int for these helpers. Using the fxp_ prefix, which makes moving these helpers outside of drm to a more generic place easier, if they prove to be useful. These are needed by later patches dumping the Display Stream Compression configuration in DRM core and in the i915 driver to replace the corresponding bpp_x16 helpers defined locally in the driver. v2: Use the more generic/descriptive fxp_q4 prefix instead of drm_x16. (Jani) Cc: Jani Nikula Acked-by: Jani Nikula Signed-off-by: Imre Deak Link: https://patchwork.freedesktop.org/patch/msgid/20240628164451.1177612-2-imre.deak@intel.com

drm: Fix drm_fixp2int_round() making it add 0.5

2024-03-19T00:28:28+00:00

As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong. To round a number, you need to add 0.5 to the number and floor that, drm_fixp2int_round() is adding 0.0000076. Make it add 0.5. [1]: https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paalanen@collabora.com/ Fixes: 8b25320887d7 ("drm: Add fixed-point helper to get rounded integer values") Suggested-by: Pekka Paalanen Reviewed-by: Harry Wentland Reviewed-by: Melissa Wen Signed-off-by: Arthur Grillo Signed-off-by: Melissa Wen Link: https://patchwork.freedesktop.org/patch/msgid/20240316-drm_fixed-v2-1-c1bc2665b5ed@riseup.net

drm: Don't treat 0 as -1 in drm_fixp2int_ceil

2024-01-02T12:57:44+00:00

Unit testing this in VKMS shows that passing 0 into this function returns -1, which is highly counter- intuitive. Fix it by checking whether the input is >= 0 instead of > 0. Fixes: 64566b5e767f ("drm: Add drm_fixp_from_fraction and drm_fixp2int_ceil") Signed-off-by: Harry Wentland Reviewed-by: Simon Ser Reviewed-by: Melissa Wen Signed-off-by: Melissa Wen Link: https://patchwork.freedesktop.org/patch/msgid/20231108163647.106853-2-harry.wentland@amd.com

drm: Add fixed-point helper to get rounded integer values

2023-05-15T13:58:10+00:00

Create a new fixed-point helper to allow us to return the rounded value of our fixed point value. [v2]: * Create the function drm_fixp2int_round() (Melissa Wen). [v3]: * Use drm_fixp2int() instead of shifting manually (Arthur Grillo). Signed-off-by: Maíra Canal Reviewed-by: Arthur Grillo Signed-off-by: Maíra Canal Link: https://patchwork.freedesktop.org/patch/msgid/20230512104044.65034-1-mcanal@igalia.com

drm: Remove unnecessary include statements for drm_crtc_helper.h

2023-01-18T08:25:30+00:00

Several DRM core and helper source files include drm_crtc_helper.h without needing it or only to get its transitive include statements; leading to unnecessary compile-time dependencies. Directly include required headers and drop drm_crtc_helper.h where possible. The header file, drm_fixed.h, includes for lower_32_bits(). v2: * include drm_crtc_helper.h in drm_crtc_helper.c (Sam) Signed-off-by: Thomas Zimmermann Reviewed-by: Sam Ravnborg Acked-by: Jani Nikula Acked-by: Alex Deucher Link: https://patchwork.freedesktop.org/patch/msgid/20230116131235.18917-3-tzimmermann@suse.de

drm: Add drm_fixp_from_fraction and drm_fixp2int_ceil

2016-02-05T05:23:48+00:00

drm_fixp_from_fraction allows us to create a fixed point directly from a fraction, rather than creating fixed point values and dividing later. This avoids overflow of our 64 bit value for large numbers. drm_fixp2int_ceil allows us to return the ceiling of our fixed point value. [airlied: squash Jordan's fix] 32-bit-build-fix: Jordan Lazare Signed-off-by: Harry Wentland Cc: stable@vger.kernel.org Reviewed-by: Alex Deucher Signed-off-by: Dave Airlie

drm: fix 64 bit drm fixed point helpers

2013-07-30T21:24:13+00:00

Sign bit wasn't handled properly and a small typo. Thanks to Christian for helping me sort this out. Signed-off-by: Alex Deucher

drm: add some additional fixed point helpers (v3)

2013-06-27T23:16:37+00:00

Required for certain driver calculations. Code was written by Christian König and ported to the drm by me. v2: fix 64 bit divides v3: fix 64 bit for real (math64.h) Signed-off-by: Alex Deucher