From mboxrd@z Thu Jan 1 00:00:00 1970 From: "james qian wang (Arm Technology China)" Subject: Re: [PATCH v2 1/4] drm: Add a new helper drm_color_ctm_s31_32_to_qm_n() Date: Mon, 14 Oct 2019 09:43:39 +0000 Message-ID: <20191014094332.GA15094@jamwan02-TSP300> References: <20191011054459.17984-1-james.qian.wang@arm.com> <20191011054459.17984-2-james.qian.wang@arm.com> <1622787.6FTe1jSl1W@e123338-lin> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <1622787.6FTe1jSl1W@e123338-lin> Content-Language: en-US Content-ID: <7382987736F7BD4E86B193C4D25E9A02@eurprd08.prod.outlook.com> Sender: linux-kernel-owner@vger.kernel.org To: Mihail Atanassov Cc: Liviu Dudau , "airlied@linux.ie" , Brian Starkey , "maarten.lankhorst@linux.intel.com" , "sean@poorly.run" , "imirkin@alum.mit.edu" , "Jonathan Chai (Arm Technology China)" , "Julien Yin (Arm Technology China)" , "Thomas Sun (Arm Technology China)" , "Lowry Li (Arm Technology China)" , Ayan Halder , "Tiannan Zhu (Arm Technology China)" , "Yiqi Kang (Arm Technology China)" , nd , "linux-kernel@vger.kernel.org" , dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org On Fri, Oct 11, 2019 at 08:26:53AM +0000, Mihail Atanassov wrote: > Hi James, >=20 > On Friday, 11 October 2019 06:45:27 BST james qian wang (Arm Technology C= hina) 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) > > --- > > 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_col= or_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, the m must <=3D 31 > > + * @n: number of fractinal bits the n must <=3D 32 @m: number of integer bits, only support m <=3D 31 @n: number of fractinal bitsm only support n <=3D 32 > > + * > > + * 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. Yes the func is only for support m <=3D 31, n <=3D 32 But I'm not sure, how to handle the unsupport case ? Maybe just mention it in Doc is enough. > > + > > + 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_preci= sion); > > +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 >=20 > --=20 > Mihail >=20 >=20