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authorImre Deak <imre.deak@intel.com>2024-06-28 18:44:42 +0200
committerImre Deak <imre.deak@intel.com>2024-07-03 17:05:12 +0200
commit58cd0cba82976a5a21bdfc78783952b147837a84 (patch)
treecd5b1ad395b37362651f38bb0fa66848d4b5d00f /include/drm
parentdrm/dp_mst: Skip CSN if topology probing is not done yet (diff)
downloadlinux-58cd0cba82976a5a21bdfc78783952b147837a84.tar.xz
linux-58cd0cba82976a5a21bdfc78783952b147837a84.zip
drm: Add helpers for q4 fixed point values
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 <jani.nikula@intel.com> Acked-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20240628164451.1177612-2-imre.deak@intel.com
Diffstat (limited to 'include/drm')
-rw-r--r--include/drm/drm_fixed.h23
1 files changed, 23 insertions, 0 deletions
diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
index 81572d32db0c..ef8bc8d72039 100644
--- a/include/drm/drm_fixed.h
+++ b/include/drm/drm_fixed.h
@@ -214,4 +214,27 @@ static inline s64 drm_fixp_exp(s64 x)
return sum;
}
+static inline int fxp_q4_from_int(int val_int)
+{
+ return val_int << 4;
+}
+
+static inline int fxp_q4_to_int(int val_q4)
+{
+ return val_q4 >> 4;
+}
+
+static inline int fxp_q4_to_int_roundup(int val_q4)
+{
+ return (val_q4 + 0xf) >> 4;
+}
+
+static inline int fxp_q4_to_frac(int val_q4)
+{
+ return val_q4 & 0xf;
+}
+
+#define FXP_Q4_FMT "%d.%04d"
+#define FXP_Q4_ARGS(val_q4) fxp_q4_to_int(val_q4), (fxp_q4_to_frac(val_q4) * 625)
+
#endif