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Message-ID: <Y8f58c5jLm/voJag@Gentoo>
Date: Wed, 18 Jan 2023 21:53:53 +0800
From: Jianhua Lu <lujianhua000@...il.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Lee Jones <lee@...nel.org>,
Daniel Thompson <daniel.thompson@...aro.org>,
Jingoo Han <jingoohan1@...il.com>, Pavel Machek <pavel@....cz>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Helge Deller <deller@....de>, linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org, linux-leds@...r.kernel.org,
devicetree@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH v6 2/2] backlight: ktz8866: Add support for Kinetic
KTZ8866 backlight
On Wed, Jan 18, 2023 at 02:39:15PM +0100, Krzysztof Kozlowski wrote:
> On 18/01/2023 14:10, Jianhua Lu wrote:
> > Add support for Kinetic KTZ8866 backlight, which is used in
> > Xiaomi tablet, Mi Pad 5 series. This driver lightly based on
> > downstream implementation [1].
> > [1] https://github.com/MiCode/Xiaomi_Kernel_OpenSource/blob/elish-r-oss/drivers/video/backlight/ktz8866.c
> >
> > Signed-off-by: Jianhua Lu <lujianhua000@...il.com>
> > ---
> > Changes in v2:
> > - Add missing staitc modifier to ktz8866_write function.
> >
> > Changes in v3:
> > - Add 2022 to Copyright line.
> > - Sort headers.
> > - Remove meaningless comment.
> > - Use definitions instead of hardcoding.
> > - Add missing maintainer info.
> >
> > Changes in v4:
> > - Change 2022 to 2023.
> > - Remove useless macro and enum.
> > - Describe settings by devicetree.
> > - Move header file to C file.
> >
> > Changes in v5:
> > - Change "2023" to "2022, 2023" in Copyright line.
> > - Set scale property for backlight.
> >
> > Changes in v6:
> > - Correct devicetree property name.
> >
> > MAINTAINERS | 6 +
> > drivers/video/backlight/Kconfig | 8 ++
> > drivers/video/backlight/Makefile | 1 +
> > drivers/video/backlight/ktz8866.c | 205 ++++++++++++++++++++++++++++++
> > 4 files changed, 220 insertions(+)
> > create mode 100644 drivers/video/backlight/ktz8866.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 42fc47c6edfd..2084e74e1b58 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -11674,6 +11674,12 @@ M: John Hawley <warthog9@...lescrag.net>
> > S: Maintained
> > F: tools/testing/ktest
> >
> > +KTZ8866 BACKLIGHT DRIVER
> > +M: Jianhua Lu <lujianhua000@...il.com>
> > +S: Maintained
> > +F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktz8866.yaml
> > +F: drivers/video/backlight/ktz8866.c
> > +
> > L3MDEV
> > M: David Ahern <dsahern@...nel.org>
> > L: netdev@...r.kernel.org
> > diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> > index 936ba1e4d35e..f7113ceb264a 100644
> > --- a/drivers/video/backlight/Kconfig
> > +++ b/drivers/video/backlight/Kconfig
> > @@ -190,6 +190,14 @@ config BACKLIGHT_KTD253
> > which is a 1-wire GPIO-controlled backlight found in some mobile
> > phones.
> >
> > +config BACKLIGHT_KTZ8866
> > + tristate "Backlight Driver for Kinetic KTZ8866"
> > + depends on I2C
> > + select REGMAP_I2C
> > + help
> > + Say Y to enable the backlight driver for the Kinetic KTZ8866
> > + found in Xiaomi Mi Pad 5 series.
> > +
> > config BACKLIGHT_LM3533
> > tristate "Backlight Driver for LM3533"
> > depends on MFD_LM3533
> > diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> > index e815f3f1deff..f70a819c304c 100644
> > --- a/drivers/video/backlight/Makefile
> > +++ b/drivers/video/backlight/Makefile
> > @@ -36,6 +36,7 @@ obj-$(CONFIG_BACKLIGHT_HP680) += hp680_bl.o
> > obj-$(CONFIG_BACKLIGHT_HP700) += jornada720_bl.o
> > obj-$(CONFIG_BACKLIGHT_IPAQ_MICRO) += ipaq_micro_bl.o
> > obj-$(CONFIG_BACKLIGHT_KTD253) += ktd253-backlight.o
> > +obj-$(CONFIG_BACKLIGHT_KTZ8866) += ktz8866.o
> > obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_bl.o
> > obj-$(CONFIG_BACKLIGHT_LM3630A) += lm3630a_bl.o
> > obj-$(CONFIG_BACKLIGHT_LM3639) += lm3639_bl.o
> > diff --git a/drivers/video/backlight/ktz8866.c b/drivers/video/backlight/ktz8866.c
> > new file mode 100644
> > index 000000000000..ca3ac349cd10
> > --- /dev/null
> > +++ b/drivers/video/backlight/ktz8866.c
> > @@ -0,0 +1,205 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Backlight driver for the Kinetic KTZ8866
> > + *
> > + * Copyright (C) 2022, 2023 Jianhua Lu <lujianhua000@...il.com>
> > + */
> > +
> > +#include <linux/backlight.h>
> > +#include <linux/delay.h>
> > +#include <linux/err.h>
> > +#include <linux/i2c.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/regmap.h>
> > +
> > +#define DEFAULT_BRIGHTNESS 1500
> > +#define MAX_BRIGHTNESS 2047
> > +#define REG_MAX 0x15
> > +
> > +/* reg */
> > +#define DEVICE_ID 0x01
> > +#define BL_CFG1 0x02
> > +#define BL_CFG2 0x03
> > +#define BL_BRT_LSB 0x04
> > +#define BL_BRT_MSB 0x05
> > +#define BL_EN 0x08
> > +#define LCD_BIAS_CFG1 0x09
> > +#define LCD_BIAS_CFG2 0x0A
> > +#define LCD_BIAS_CFG3 0x0B
> > +#define LCD_BOOST_CFG 0x0C
> > +#define OUTP_CFG 0x0D
> > +#define OUTN_CFG 0x0E
> > +#define FLAG 0x0F
> > +#define BL_OPTION1 0x10
> > +#define BL_OPTION2 0x11
> > +#define PWM2DIG_LSBs 0x12
> > +#define PWM2DIG_MSBs 0x13
> > +#define BL_DIMMING 0x14
> > +#define PWM_RAMP_TIME 0x15
> > +
> > +/* definition */
> > +#define BL_EN_BIT BIT(6)
> > +#define LCD_BIAS_EN 0x9F
> > +#define PWM_HYST 0x5
> > +
> > +struct ktz8866 {
> > + struct i2c_client *client;
> > + struct regmap *regmap;
> > + bool led_on;
> > +};
> > +
> > +static const struct regmap_config ktz8866_regmap_config = {
> > + .reg_bits = 8,
> > + .val_bits = 8,
> > + .max_register = REG_MAX,
> > +};
> > +
> > +static int ktz8866_write(struct ktz8866 *ktz, unsigned int reg,
> > + unsigned int val)
> > +{
> > + return regmap_write(ktz->regmap, reg, val);
> > +}
> > +
> > +static int ktz8866_update_bits(struct ktz8866 *ktz, unsigned int reg,
> > + unsigned int mask, unsigned int val)
> > +{
> > + return regmap_update_bits(ktz->regmap, reg, mask, val);
> > +}
> > +
> > +static int ktz8866_backlight_update_status(struct backlight_device *backlight_dev)
> > +{
> > + struct ktz8866 *ktz = bl_get_data(backlight_dev);
> > + unsigned int brightness = backlight_get_brightness(backlight_dev);
> > +
> > + if (!ktz->led_on && brightness > 0) {
> > + ktz8866_update_bits(ktz, BL_EN, BL_EN_BIT, BL_EN_BIT);
> > + ktz->led_on = true;
> > + } else if (brightness == 0) {
> > + ktz8866_update_bits(ktz, BL_EN, BL_EN_BIT, 0);
> > + ktz->led_on = false;
> > + msleep(10);
>
> Why 10 ms? Document magic values. Their need, reason behind.
>
> > + }
> > +
> > + /* Set brightness */
> > + ktz8866_write(ktz, BL_BRT_LSB, brightness & 0x7);
> > + ktz8866_write(ktz, BL_BRT_MSB, (brightness >> 3) & 0xFF);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct backlight_ops ktz8866_backlight_ops = {
> > + .options = BL_CORE_SUSPENDRESUME,
> > + .update_status = ktz8866_backlight_update_status,
> > +};
> > +
> > +static void ktz8866_init(struct ktz8866 *ktz)
> > +{
> > + unsigned int val;
> > +
> > + if(of_property_read_u32(ktz->client->dev.of_node, "current-num-sinks", &val))
>
> Here and in other places - not conforming to coding style. Missing space
> before (.
>
> Be sure you run checkpatch --strict and fix all relevant errors.
>
> > + ktz8866_write(ktz, BL_EN, BIT(val) - 1);
> > + else
> > + /* Enable all 6 current sinks if the number of current sinks isn't specifed. */
> > + ktz8866_write(ktz, BL_EN, BIT(6) - 1);
> > +
> > + if(of_property_read_u32(ktz->client->dev.of_node, "current-ramping-time-ms", &val)) {
> > + if(val <= 128) {
> > + ktz8866_write(ktz, BL_CFG2, BIT(7) | (ilog2(val) << 3) | PWM_HYST);
> > + } else {
> > + ktz8866_write(ktz, BL_CFG2, BIT(7) | ((5 + val / 64) << 3) | PWM_HYST);
> > + }
> > + }
> > +
> > + if(of_property_read_u32(ktz->client->dev.of_node, "led-ramping-time-ms", &val)) {
> > + if(val == 0) {
> > + ktz8866_write(ktz, BL_DIMMING, 0);
> > + } else {
> > + unsigned int ramp_off_time = ilog2(val) + 1;
> > + unsigned int ramp_on_time = ramp_off_time << 4;
> > + ktz8866_write(ktz, BL_DIMMING, ramp_on_time | ramp_off_time);
> > + }
> > + }
> > +
> > + if(of_property_read_bool(ktz->client->dev.of_node, "enable-lcd-bias"))
> > + ktz8866_write(ktz, LCD_BIAS_CFG1, LCD_BIAS_EN);
> > +}
> > +
> > +static int ktz8866_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> > + struct backlight_device *backlight_dev;
> > + struct backlight_properties props;
> > + struct ktz8866 *ktz;
> > +
> > + ktz = devm_kzalloc(&client->dev, sizeof(*ktz), GFP_KERNEL);
> > + if (!ktz)
> > + return -ENOMEM;
> > +
> > + ktz->client = client;
> > + ktz->regmap = devm_regmap_init_i2c(client, &ktz8866_regmap_config);
> > +
>
> Drop blank line
>
> > + if (IS_ERR(ktz->regmap)) {
> > + dev_err(&client->dev, "failed to init regmap\n");
>
> dev_err_probe
>
> > + return PTR_ERR(ktz->regmap);
> > + }
> > +
> > + memset(&props, 0, sizeof(props));
> > + props.type = BACKLIGHT_RAW;
> > + props.max_brightness = MAX_BRIGHTNESS;
> > + props.brightness = DEFAULT_BRIGHTNESS;
> > + props.scale = BACKLIGHT_SCALE_LINEAR;
> > +
> > + backlight_dev = devm_backlight_device_register(
> > + &client->dev, "ktz8866-backlight", &client->dev, ktz,> + &ktz8866_backlight_ops, &props);
> > +
>
> Drop blank line
>
> > + if (IS_ERR(backlight_dev)) {
> > + dev_err(&client->dev, "failed to register backlight device\n");
>
> dev_err_probe
>
> > + return PTR_ERR(backlight_dev);
> > + }
> > +
> > + ktz8866_init(ktz);
> > +
> > + i2c_set_clientdata(client, backlight_dev);
> > + backlight_update_status(backlight_dev);
> > +
> > + return 0;
> > +}
> > +
> > +static void ktz8866_remove(struct i2c_client *client)
> > +{
> > + struct backlight_device *backlight_dev = i2c_get_clientdata(client);
> > +
> > + backlight_dev->props.brightness = 0;
> > + backlight_update_status(backlight_dev);
> > +}
> > +
> > +static const struct i2c_device_id ktz8866_ids[] = {
> > + { "ktz8866", 0 },
> > + {},
> > +};
> > +MODULE_DEVICE_TABLE(i2c, ktz8866_ids);
> > +
> > +static const struct of_device_id ktz8866_match_table[] = {
> > + {
> > + .compatible = "kinetic,ktz8866",
> > + },
> > + {},
> > +};
> > +
> > +static struct i2c_driver ktz8866_driver = {
> > + .driver = {
> > + .name = "ktz8866",
> > + .of_match_table = ktz8866_match_table,
> > + },
> > + .probe = ktz8866_probe,
> > + .remove = ktz8866_remove,
> > + .id_table = ktz8866_ids,
> > +};
> > +
> > +module_i2c_driver(ktz8866_driver);
> > +
> > +MODULE_DESCRIPTION("Kinetic KTZ8866 Backlight Driver");
> > +MODULE_AUTHOR("Jianhua Lu <lujianhua000@...il.com>");
> > +MODULE_LICENSE("GPL");
>
> Best regards,
> Krzysztof
>
I will send new version patches, thanks.
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