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Message-ID: <20191016103339.25858-2-james.qian.wang@arm.com>
Date: Wed, 16 Oct 2019 10:34:08 +0000
From: "james qian wang (Arm Technology China)" <james.qian.wang@....com>
To: Liviu Dudau <Liviu.Dudau@....com>,
"airlied@...ux.ie" <airlied@...ux.ie>,
Brian Starkey <Brian.Starkey@....com>,
"maarten.lankhorst@...ux.intel.com"
<maarten.lankhorst@...ux.intel.com>,
"sean@...rly.run" <sean@...rly.run>,
"imirkin@...m.mit.edu" <imirkin@...m.mit.edu>
CC: "Jonathan Chai (Arm Technology China)" <Jonathan.Chai@....com>,
"Julien Yin (Arm Technology China)" <Julien.Yin@....com>,
"Thomas Sun (Arm Technology China)" <thomas.Sun@....com>,
"Lowry Li (Arm Technology China)" <Lowry.Li@....com>,
Ayan Halder <Ayan.Halder@....com>,
"Tiannan Zhu (Arm Technology China)" <Tiannan.Zhu@....com>,
"Yiqi Kang (Arm Technology China)" <Yiqi.Kang@....com>,
nd <nd@....com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
Ben Davis <Ben.Davis@....com>,
"Oscar Zhang (Arm Technology China)" <Oscar.Zhang@....com>,
"Channing Chen (Arm Technology China)" <Channing.Chen@....com>,
Mihail Atanassov <Mihail.Atanassov@....com>,
"james qian wang (Arm Technology China)" <james.qian.wang@....com>,
Daniel Vetter <daniel.vetter@...ll.ch>
Subject: [PATCH v5 1/4] drm: Add a new helper drm_color_ctm_s31_32_to_qm_n()
Add a new helper function drm_color_ctm_s31_32_to_qm_n() for driver to
convert S31.32 sign-magnitude to Qm.n 2's complement that supported by
hardware.
V4: Address Mihai, Daniel and Ilia's review comments.
V5: Includes the sign bit in the value of m (Qm.n).
Signed-off-by: james qian wang (Arm Technology China) <james.qian.wang@....com>
Reviewed-by: Mihail Atanassov <mihail.atanassov@....com>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
---
drivers/gpu/drm/drm_color_mgmt.c | 27 +++++++++++++++++++++++++++
include/drm/drm_color_mgmt.h | 2 ++
2 files changed, 29 insertions(+)
diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
index 4ce5c6d8de99..d313f194f1ec 100644
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -132,6 +132,33 @@ uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precision)
}
EXPORT_SYMBOL(drm_color_lut_extract);
+/**
+ * drm_color_ctm_s31_32_to_qm_n
+ *
+ * @user_input: input value
+ * @m: number of integer bits, include the sign-bit, support range is [1, 32]
+ * @n: number of fractional bits, only support n <= 32
+ *
+ * Convert and clamp S31.32 sign-magnitude to Qm.n (signed 2's complement). The
+ * higher bits that above m + n are cleared or equal to sign-bit BIT(m+n).
+ */
+uint64_t drm_color_ctm_s31_32_to_qm_n(uint64_t user_input,
+ uint32_t m, uint32_t n)
+{
+ u64 mag = (user_input & ~BIT_ULL(63)) >> (32 - n);
+ bool negative = !!(user_input & BIT_ULL(63));
+ s64 val;
+
+ WARN_ON(m < 1 || m > 32 || n > 32);
+
+ /* the range of signed 2's complement is [-2^(m-1), 2^(m-1) - 2^-n] */
+ val = clamp_val(mag, 0, negative ?
+ BIT_ULL(n + m - 1) : BIT_ULL(n + m - 1) - 1);
+
+ return negative ? -val : val;
+}
+EXPORT_SYMBOL(drm_color_ctm_s31_32_to_qm_n);
+
/**
* 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..60fea5501886 100644
--- a/include/drm/drm_color_mgmt.h
+++ b/include/drm/drm_color_mgmt.h
@@ -30,6 +30,8 @@ struct drm_crtc;
struct drm_plane;
uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precision);
+uint64_t drm_color_ctm_s31_32_to_qm_n(uint64_t user_input,
+ uint32_t m, uint32_t n);
void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
uint degamma_lut_size,
--
2.20.1
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