linux-kernel - Re: [PATCH 13/17] drm/sun4i: Add DE2 CSC library

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Message-ID: <CAGb2v67+4AmUVSipY2ncwQ1i8PVZmysuZYSQ-uY9+Uk1KU9EgA@mail.gmail.com>
Date:   Wed, 29 Nov 2017 11:20:15 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     Jernej Škrabec <jernej.skrabec@...l.net>
Cc:     Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>, David Airlie <airlied@...ux.ie>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Icenowy Zheng <icenowy@...c.io>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH 13/17] drm/sun4i: Add DE2 CSC library

On Wed, Nov 29, 2017 at 5:43 AM, Jernej Škrabec <jernej.skrabec@...l.net> wrote:
> Hi!
>
> Dne torek, 28. november 2017 ob 21:55:50 CET je Maxime Ripard napisal(a):
>> On Mon, Nov 27, 2017 at 09:57:46PM +0100, Jernej Skrabec wrote:
>> > DE2 have many CSC units - channel input CSC, channel output CSC and
>> > mixer output CSC and maybe more.
>> >
>> > Fortunately, they have all same register layout, only base offsets
>> > differs.
>> >
>> > Add support only for channel output CSC for now.
>> >
>> > Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
>> > ---
>> >
>> >  drivers/gpu/drm/sun4i/Makefile    |  2 +-
>> >  drivers/gpu/drm/sun4i/sun8i_csc.c | 90
>> >  +++++++++++++++++++++++++++++++++++++++
>> >  drivers/gpu/drm/sun4i/sun8i_csc.h | 36 ++++++++++++++++
>> >  3 files changed, 127 insertions(+), 1 deletion(-)
>> >  create mode 100644 drivers/gpu/drm/sun4i/sun8i_csc.c
>> >  create mode 100644 drivers/gpu/drm/sun4i/sun8i_csc.h
>> >
>> > diff --git a/drivers/gpu/drm/sun4i/Makefile
>> > b/drivers/gpu/drm/sun4i/Makefile index 70df480792f9..f82cc69ede72 100644
>> > --- a/drivers/gpu/drm/sun4i/Makefile
>> > +++ b/drivers/gpu/drm/sun4i/Makefile
>> > @@ -9,7 +9,7 @@ sun4i-drm-hdmi-y            += sun4i_hdmi_enc.o
>> >
>> >  sun4i-drm-hdmi-y           += sun4i_hdmi_i2c.o
>> >  sun4i-drm-hdmi-y           += sun4i_hdmi_tmds_clk.o
>> >
>> > -sun8i-mixer-y                      += sun8i_mixer.o sun8i_layer.o sun8i_scaler.o
>> > +sun8i-mixer-y                      += sun8i_mixer.o sun8i_layer.o sun8i_scaler.o
> sun8i_csc.o
>>
>> Please wrap that line.
>>
>> >  sun4i-tcon-y                       += sun4i_crtc.o
>> >  sun4i-tcon-y                       += sun4i_dotclock.o
>> >
>> > diff --git a/drivers/gpu/drm/sun4i/sun8i_csc.c
>> > b/drivers/gpu/drm/sun4i/sun8i_csc.c new file mode 100644
>> > index 000000000000..d48c28f8d568
>> > --- /dev/null
>> > +++ b/drivers/gpu/drm/sun4i/sun8i_csc.c
>> > @@ -0,0 +1,90 @@
>> > +/*
>> > + * Copyright (C) Jernej Skrabec <jernej.skrabec@...l.net>
>> > + *
>> > + * This program is free software; you can redistribute it and/or
>> > + * modify it under the terms of the GNU General Public License as
>> > + * published by the Free Software Foundation; either version 2 of
>> > + * the License, or (at your option) any later version.
>> > + */
>> > +
>> > +#include "sun8i_csc.h"
>> > +
>> > +static const u32 ccsc_base[2][2] = {
>> > +   {CCSC00_OFFSET, CCSC01_OFFSET},
>> > +   {CCSC10_OFFSET, CCSC11_OFFSET},
>> > +};
>> > +
>> > +/*
>> > + * Factors are in two's complement format, 10 bits for fractinal part.
>> > + * First tree values in each line are multiplication factor and last
>> > + * value is constant, which is added at the end.
>> > + */
>> > +static const u32 yuv2rgb[] = {
>> > +   0x000004A8, 0x00000000, 0x00000662, 0xFFFC845A,
>> > +   0x000004A8, 0xFFFFFE6F, 0xFFFFFCBF, 0x00021DF4,
>> > +   0x000004A8, 0x00000813, 0x00000000, 0xFFFBAC4A,
>> > +};
>> > +
>> > +static const u32 yvu2rgb[] = {
>> > +   0x000004A8, 0x00000662, 0x00000000, 0xFFFC845A,
>> > +   0x000004A8, 0xFFFFFCBF, 0xFFFFFE6F, 0x00021DF4,
>> > +   0x000004A8, 0x00000000, 0x00000813, 0xFFFBAC4A,
>> > +};
>> > +
>> > +static void sun8i_csc_set_coefficients(struct regmap *map, u32 base,
>> > +                                  enum sun8i_csc_mode mode)
>> > +{
>> > +   const u32 *table;
>> > +   int i, data;
>> > +
>> > +   switch (mode) {
>> > +   case SUN8I_CSC_MODE_YUV2RGB:
>> > +           table = yuv2rgb;
>> > +           break;
>> > +   case SUN8I_CSC_MODE_YVU2RGB:
>> > +           table = yvu2rgb;
>> > +           break;
>> > +   default:
>> > +           WARN(1, "Wrong CSC mode specified.");
>>
>> A hard warn is a bit overkill here. What about a dev_warn?
>
> dev_warn requires device, which is not available here and seems a bit overkill
> to have it as parameter just to print warning. What about DRM_WARN()?

dev_warn is just pr_warn that prefixes the device name to the message.
Not sure about DRM_WARN. If it's anything like DRM_DEBUG* then it probably
prefixes the function name.

ChenYu