Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Received-SPF: TempError (protection.outlook.com: error in processing during
 lookup of arm.com: DNS Timeout)
From:   Mihail Atanassov <Mihail.Atanassov@arm.com>
To:     "james qian wang (Arm Technology China)" <james.qian.wang@arm.com>
CC:     Liviu Dudau <Liviu.Dudau@arm.com>,
        "airlied@linux.ie" <airlied@linux.ie>,
        Brian Starkey <Brian.Starkey@arm.com>,
        "maarten.lankhorst@linux.intel.com" 
        <maarten.lankhorst@linux.intel.com>,
        "sean@poorly.run" <sean@poorly.run>,
        "imirkin@alum.mit.edu" <imirkin@alum.mit.edu>,
        "Jonathan Chai (Arm Technology China)" <Jonathan.Chai@arm.com>,
        "Julien Yin (Arm Technology China)" <Julien.Yin@arm.com>,
        "Thomas Sun (Arm Technology China)" <thomas.Sun@arm.com>,
        "Lowry Li (Arm Technology China)" <Lowry.Li@arm.com>,
        Ayan Halder <Ayan.Halder@arm.com>,
        "Tiannan Zhu (Arm Technology China)" <Tiannan.Zhu@arm.com>,
        "Yiqi Kang (Arm Technology China)" <Yiqi.Kang@arm.com>,
        nd <nd@arm.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        Ben Davis <Ben.Davis@arm.com>,
        "Oscar Zhang (Arm Technology China)" <Oscar.Zhang@arm.com>,
        "Channing Chen (Arm Technology China)" <Channing.Chen@arm.com>
Subject: Re: [PATCH v2 1/4] drm: Add a new helper
 drm_color_ctm_s31_32_to_qm_n()
Thread-Topic: [PATCH v2 1/4] drm: Add a new helper
 drm_color_ctm_s31_32_to_qm_n()
Thread-Index: AQHVf/cdAHid3tH8+UyzZeXX5YE1LKdVG1SA
Date:   Fri, 11 Oct 2019 08:26:53 +0000
Message-ID: <1622787.6FTe1jSl1W@e123338-lin>
References: <20191011054459.17984-1-james.qian.wang@arm.com>
 <20191011054459.17984-2-james.qian.wang@arm.com>
In-Reply-To: <20191011054459.17984-2-james.qian.wang@arm.com>
Accept-Language: en-GB, en-US
Content-Language: en-US
Authentication-Results-Original: spf=none (sender IP is )
 smtp.mailfrom=Mihail.Atanassov@arm.com; 
x-ms-exchange-messagesentrepresentingtype: 1
x-ms-publictraffictype: Email
X-MS-Office365-Filtering-Correlation-Id: 111736a0-2d67-4b08-7ab5-08d74e24ca2a
X-MS-Office365-Filtering-HT: Tenant
X-MS-TrafficTypeDiagnostic: VI1PR08MB4093:|VI1PR08MB4093:|VI1PR08MB3630:
x-ms-exchange-transport-forked: True
X-Microsoft-Antispam-PRVS: <VI1PR08MB3630A41D0181463E999AA4B18F970@VI1PR08MB3630.eurprd08.prod.outlook.com>
x-checkrecipientrouted: true
x-ms-oob-tlc-oobclassifiers: OLM:4125;OLM:4125;
x-forefront-prvs: 0187F3EA14
X-Forefront-Antispam-Report-Untrusted: SFV:NSPM;SFS:(10009020)(4636009)(7916004)(366004)(346002)(376002)(39860400002)(396003)(136003)(189003)(199004)(64756008)(6636002)(256004)(186003)(66446008)(476003)(71200400001)(14444005)(316002)(8676002)(86362001)(486006)(5660300002)(71190400001)(3846002)(7736002)(2906002)(66556008)(66476007)(446003)(11346002)(54906003)(81166006)(81156014)(6116002)(66946007)(25786009)(6862004)(26005)(66066001)(102836004)(8936002)(6246003)(305945005)(6436002)(52116002)(478600001)(9686003)(6512007)(6506007)(386003)(229853002)(4326008)(76176011)(14454004)(6486002)(33716001)(99286004)(39026011);DIR:OUT;SFP:1101;SCL:1;SRVR:VI1PR08MB4093;H:VI1PR08MB4078.eurprd08.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1;
received-spf: None (protection.outlook.com: arm.com does not designate
 permitted sender hosts)
X-MS-Exchange-SenderADCheck: 1
X-Microsoft-Antispam-Untrusted: BCL:0;
X-Microsoft-Antispam-Message-Info-Original: nBG0TXM9rTUg9IsPImGxzNUlEbC+DmYCU7DtbwvVcQZcHRtl6uNgTyYLUUSpMbDBZBzIAMU5BlXQEv9FotuxVOEp9TNILAmABBcxowPCtWqy7GX9WrBT9LyXKi2aqyJo+MF3lElh7v1I0SFX/2FjH7hDnOTG3WcCDiRjqzJYK8rDDVitDlTdkhWnavgCVJH17ZRBU9WAofU0LWeARuUIDopLGnAYyVvL4KCfAII//hcO0i2LyqrweV5Pmpg35806m0gbL87JS2Nq3cqSp8d4GrIKZGvA3eNYhy1xo+b9Tqtjyge51bF/UTVnTe4Hal8J1ax1tTYuMU9tpDs5qo5Tx/H2bfJvVB8upFaqB2WNiqawq6B1gPrm1obsCxKMZVjKDvR2Vk89my7LQcCwmlKjE5Qs8/us6OEt0aR6o3rqYYw=
Content-Type: text/plain; charset="us-ascii"
Content-ID: <8E9A0D14D6ECF7498045A0969AF1E44E@eurprd08.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR08MB4093
Original-Authentication-Results: spf=none (sender IP is )
 smtp.mailfrom=Mihail.Atanassov@arm.com; 
X-EOPAttributedMessage: 0
X-MS-Exchange-Transport-CrossTenantHeadersStripped: VE1EUR03FT008.eop-EUR03.prod.protection.outlook.com
X-Forefront-Antispam-Report: CIP:63.35.35.123;IPV:CAL;SCL:-1;CTRY:IE;EFV:NLI;SFV:NSPM;SFS:(10009020)(7916004)(4636009)(346002)(376002)(396003)(136003)(39860400002)(199004)(189003)(486006)(476003)(26005)(99286004)(6636002)(446003)(3846002)(14444005)(386003)(6506007)(305945005)(2906002)(63350400001)(126002)(11346002)(6116002)(23726003)(336012)(102836004)(33716001)(5660300002)(186003)(86362001)(8746002)(8936002)(76176011)(8676002)(81166006)(81156014)(229853002)(356004)(50466002)(70586007)(14454004)(36906005)(316002)(54906003)(76130400001)(70206006)(6246003)(6862004)(22756006)(478600001)(26826003)(7736002)(66066001)(4326008)(47776003)(46406003)(97756001)(9686003)(6512007)(6486002)(25786009)(39026011);DIR:OUT;SFP:1101;SCL:1;SRVR:VI1PR08MB3630;H:64aa7808-outbound-1.mta.getcheckrecipient.com;FPR:;SPF:TempError;LANG:en;PTR:ec2-63-35-35-123.eu-west-1.compute.amazonaws.com;A:1;MX:1;
X-MS-Office365-Filtering-Correlation-Id-Prvs: 4dbc0383-0883-4a07-3976-08d74e24c54f
NoDisclaimer: True
X-Forefront-PRVS: 0187F3EA14
X-Microsoft-Antispam: BCL:0;
X-Microsoft-Antispam-Message-Info: 7j/MYp0+gt0prpHsbljDhrJmeD5Xp+u3Rv7pPk8APgrms8u0zkqyMHwBRyNNBDeMLf40TGTB4jA9C9uxspkPKVA/638sFEJEGEtezaJoF6LF24/syoDJS3Pj37+yYhmPJ/VS+BArn7nZtCYorTvXTaapvetQxgeJZsfztP+olqMCHdWygf/TXSaQo+ac4s2Gnim8xRi2NFJrlZoagTkoEykfH7KSs9SvSmRMC2QmEQndb2W8IE97mxySq0Fo01ZOIZe98MM3644yAYWwzge5Ezph81XylOtzUSmPj8bqx8xGjDQXNsKTpmHjD/Bx+MWoAKf/VIN+nUKvYXvwqSH6iKumtlliWKuxTwPInTd9odDrPpVEE3WPL/QjeXxRNs3d1AuXIrfdpyoM5gQZoz8n/xjYtxpYyPgJQEgT8hkDJMA=
X-OriginatorOrg: arm.com
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Oct 2019 08:27:01.2714
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 111736a0-2d67-4b08-7ab5-08d74e24ca2a
X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[63.35.35.123];Helo=[64aa7808-outbound-1.mta.getcheckrecipient.com]
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR08MB3630
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi James,

On Friday, 11 October 2019 06:45:27 BST james qian wang (Arm Technology Chi=
na) wrote:
> 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.
>=20
> Signed-off-by: james qian wang (Arm Technology China) <james.qian.wang@ar=
m.com>
> ---
>  drivers/gpu/drm/drm_color_mgmt.c | 23 +++++++++++++++++++++++
>  include/drm/drm_color_mgmt.h     |  2 ++
>  2 files changed, 25 insertions(+)
>=20
> diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color=
_mgmt.c
> index 4ce5c6d8de99..3d533d0b45af 100644
> --- a/drivers/gpu/drm/drm_color_mgmt.c
> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> @@ -132,6 +132,29 @@ uint32_t drm_color_lut_extract(uint32_t user_input, =
uint32_t bit_precision)
>  }
>  EXPORT_SYMBOL(drm_color_lut_extract);
>=20
> +/**
> + * drm_color_ctm_s31_32_to_qm_n
> + *
> + * @user_input: input value
> + * @m: number of integer bits
> + * @n: number of fractinal bits
> + *
> + * Convert and clamp S31.32 sign-magnitude to Qm.n 2's complement.
> + */
> +uint64_t drm_color_ctm_s31_32_to_qm_n(uint64_t user_input,
> +				      uint32_t m, uint32_t n)
> +{
> +	u64 mag =3D (user_input & ~BIT_ULL(63)) >> (32 - n);
This doesn't account for n > 32, which is perfectly possible (e.g. Q1.63).
> +	bool negative =3D !!(user_input & BIT_ULL(63));
> +	s64 val;
> +
> +	/* the range of signed 2s complement is [-2^n+m, 2^n+m - 1] */
> +	val =3D clamp_val(mag, 0, negative ? BIT(n + m) : BIT(n + m) - 1);
This also doesn't account for n + m =3D=3D 64.
> +
> +	return negative ? 0ll - 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;
>=20
>  uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precisi=
on);
> +uint64_t drm_color_ctm_s31_32_to_qm_n(uint64_t user_input,
> +				      uint32_t m, uint32_t n);
>=20
>  void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
>  				uint degamma_lut_size,
> --
> 2.20.1
>=20


--=20
Mihail