On 2019-11-07 10:17 a.m., Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
This thing can get called several thousand times per LUT so seems like we want to inline it to:
- avoid the function call overhead
- allow constant folding
A quick synthetic test (w/o any hardware interaction) with a ridiculously large LUT size shows about 50% reduction in runtime on my HSW and BSW boxes. Slightly less with more reasonable LUT size but still easily measurable in tens of microseconds.
Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
Reviewed-by: Nicholas Kazlauskas nicholas.kazlauskas@amd.com
Seems reasonable to me. It would probably make sense to even split this further into two functions, one for high precision and one for low precision so it's purely a calculation and not hitting any branches.
Nicholas Kazlauskas
drivers/gpu/drm/drm_color_mgmt.c | 24 ------------------------ include/drm/drm_color_mgmt.h | 23 ++++++++++++++++++++++- 2 files changed, 22 insertions(+), 25 deletions(-)
diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c index 4ce5c6d8de99..19c5f635992a 100644 --- a/drivers/gpu/drm/drm_color_mgmt.c +++ b/drivers/gpu/drm/drm_color_mgmt.c @@ -108,30 +108,6 @@
- standard enum values supported by the DRM plane.
*/
-/**
- drm_color_lut_extract - clamp and round LUT entries
- @user_input: input value
- @bit_precision: number of bits the hw LUT supports
- Extract a degamma/gamma LUT value provided by user (in the form of
- &drm_color_lut entries) and round it to the precision supported by the
- hardware.
- */
-uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precision) -{
- uint32_t val = user_input;
- uint32_t max = 0xffff >> (16 - bit_precision);
- /* Round only if we're not using full precision. */
- if (bit_precision < 16) {
val += 1UL << (16 - bit_precision - 1);val >>= 16 - bit_precision;- }
- return clamp_val(val, 0, max);
-} -EXPORT_SYMBOL(drm_color_lut_extract);
- /**
- drm_crtc_enable_color_mgmt - enable color management properties
- @crtc: DRM CRTC
diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h index d1c662d92ab7..069b21d61871 100644 --- a/include/drm/drm_color_mgmt.h +++ b/include/drm/drm_color_mgmt.h @@ -29,7 +29,28 @@ struct drm_crtc; struct drm_plane;
-uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precision); +/**
- drm_color_lut_extract - clamp and round LUT entries
- @user_input: input value
- @bit_precision: number of bits the hw LUT supports
- Extract a degamma/gamma LUT value provided by user (in the form of
- &drm_color_lut entries) and round it to the precision supported by the
- hardware.
- */
+static inline u32 drm_color_lut_extract(u32 user_input, int bit_precision) +{
- u32 val = user_input;
- u32 max = 0xffff >> (16 - bit_precision);
- /* Round only if we're not using full precision. */
- if (bit_precision < 16) {
val += 1UL << (16 - bit_precision - 1);val >>= 16 - bit_precision;- }
- return clamp_val(val, 0, max);
+}
void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc, uint degamma_lut_size,