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From: Arthur Grillo <arthurgrillo@riseup.net>
Date: Wed, 06 Mar 2024 17:03:08 -0300
Subject: [PATCH 1/7] drm: Fix drm_fixp2int_round() making it add 0.5
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To: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>, 
 Melissa Wen <melissa.srw@gmail.com>, 
 =?utf-8?q?Ma=C3=ADra_Canal?= <mairacanal@riseup.net>, 
 Haneen Mohammed <hamohammed.sa@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
 Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, 
 Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de>, 
 David Airlie <airlied@gmail.com>, arthurgrillo@riseup.net, 
 Jonathan Corbet <corbet@lwn.net>, pekka.paalanen@haloniitty.fi, 
 Louis Chauvet <louis.chauvet@bootlin.com>
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, 
 jeremie.dautheribes@bootlin.com, miquel.raynal@bootlin.com, 
 thomas.petazzoni@bootlin.com, seanpaul@google.com, marcheu@google.com, 
 nicolejadeyee@google.com, Pekka Paalanen <pekka.paalanen@collabora.com>

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/

Suggested-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
---
 include/drm/drm_fixed.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
index 0c9f917a4d4b..de3a79909ac9 100644
--- a/include/drm/drm_fixed.h
+++ b/include/drm/drm_fixed.h
@@ -90,7 +90,7 @@ static inline int drm_fixp2int(s64 a)
 
 static inline int drm_fixp2int_round(s64 a)
 {
-	return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
+	return drm_fixp2int(a + DRM_FIXED_ONE / 2);
 }
 
 static inline int drm_fixp2int_ceil(s64 a)

-- 
2.43.0