From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: Re: [PATCH 2/2] leds: Add driver for NCP5623 3-channel I2C LED driver Date: Wed, 22 Jun 2016 09:26:45 +0200 Message-ID: <576A3DB5.4080703@samsung.com> References: <1466494154-3786-1-git-send-email-florian.vaussard@heig-vd.ch> <1466494154-3786-3-git-send-email-florian.vaussard@heig-vd.ch> <57695D45.60107@samsung.com> <9375e68a-9920-8e84-419d-890f57b6c9d2@heig-vd.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-reply-to: <9375e68a-9920-8e84-419d-890f57b6c9d2@heig-vd.ch> Sender: linux-leds-owner@vger.kernel.org To: Florian Vaussard Cc: Florian Vaussard , devicetree@vger.kernel.org, Richard Purdie , Rob Herring , Mark Rutland , linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: devicetree@vger.kernel.org Hi Florian, On 06/22/2016 08:08 AM, Florian Vaussard wrote: > Hi Jacek, > > Le 21. 06. 16 =E0 17:29, Jacek Anaszewski a =E9crit : >> Hi Florian, >> >> Thanks for the patch. Please refer to my comments in the code. >> > > Thanks for your review. I completely agree with you, I will address y= our > comments in V2. I just have one small question below. > >> On 06/21/2016 09:29 AM, Florian Vaussard wrote: >>> The NCP5623 is a 3-channel LED driver from On Semiconductor control= led >>> through I2C. The PWM of each channel can be independently set with = 32 >>> distinct levels. In addition, the intensity of the current source c= an be >>> globally set using an external bias resistor fixing the reference >>> current (Iref) and a dedicated register (ILED), following the >>> relationship: >>> >>> I =3D 2400*Iref/(31-ILED) >>> >>> with Iref =3D Vref/Rbias, and Vref =3D 0.6V. >>> >>> Signed-off-by: Florian Vaussard >>> --- >>> drivers/leds/Kconfig | 11 ++ >>> drivers/leds/Makefile | 1 + >>> drivers/leds/leds-ncp5623.c | 265 ++++++++++++++++++++++++++++++= ++++++++++++++ >>> 3 files changed, 277 insertions(+) >>> create mode 100644 drivers/leds/leds-ncp5623.c >>> >>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig >>> index 5ae2834..6d3e44d 100644 >>> --- a/drivers/leds/Kconfig >>> +++ b/drivers/leds/Kconfig >>> @@ -588,6 +588,17 @@ config LEDS_BLINKM >>> This option enables support for the BlinkM RGB LED connect= ed >>> through I2C. Say Y to enable support for the BlinkM LED. >>> >>> +config LEDS_NCP5623 >>> + tristate "LED Support for NCP5623 I2C chip" >>> + depends on LEDS_CLASS >>> + depends on I2C >>> + help >>> + This option enables support for LEDs connected to NCP5623 >>> + LED driver chips accessed via the I2C bus. >>> + Driver supports brightness control. >>> + >>> + Say Y to enable this driver. >>> + >>> config LEDS_POWERNV >>> tristate "LED support for PowerNV Platform" >>> depends on LEDS_CLASS >>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile >>> index cb2013d..a2f0e10 100644 >>> --- a/drivers/leds/Makefile >>> +++ b/drivers/leds/Makefile >>> @@ -67,6 +67,7 @@ obj-$(CONFIG_LEDS_KTD2692) +=3D leds-ktd26= 92.o >>> obj-$(CONFIG_LEDS_POWERNV) +=3D leds-powernv.o >>> obj-$(CONFIG_LEDS_SEAD3) +=3D leds-sead3.o >>> obj-$(CONFIG_LEDS_IS31FL32XX) +=3D leds-is31fl32xx.o >>> +obj-$(CONFIG_LEDS_NCP5623) +=3D leds-ncp5623.o >>> >>> # LED SPI Drivers >>> obj-$(CONFIG_LEDS_DAC124S085) +=3D leds-dac124s085.o >>> diff --git a/drivers/leds/leds-ncp5623.c b/drivers/leds/leds-ncp562= 3.c >>> new file mode 100644 >>> index 0000000..a341e4a >>> --- /dev/null >>> +++ b/drivers/leds/leds-ncp5623.c >>> @@ -0,0 +1,265 @@ >>> +/* >>> + * Copyright 2016 Florian Vaussard >>> + * >>> + * Based on leds-tlc591xx.c >>> + * >>> + * This program is free software; you can redistribute it and/or m= odify >>> + * it under the terms of the GNU General Public License as publish= ed by >>> + * the Free Software Foundation; version 2 of the License. >>> + */ >>> + >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> + >>> +#define NCP5623_MAX_LEDS 3 >>> +#define NCP5623_MAX_STEPS 32 >>> +#define NCP5623_MAX_CURRENT 31 >>> +#define NCP5623_MAX_CURRENT_UA 30000 >>> + >>> +#define NCP5623_CMD_SHIFT 5 >>> +#define CMD_SHUTDOWN (0x00 << NCP5623_CMD_SHIFT) >>> +#define CMD_ILED (0x01 << NCP5623_CMD_SHIFT) >>> +#define CMD_PWM1 (0x02 << NCP5623_CMD_SHIFT) >>> +#define CMD_PWM2 (0x03 << NCP5623_CMD_SHIFT) >>> +#define CMD_PWM3 (0x04 << NCP5623_CMD_SHIFT) >>> +#define CMD_UPWARD_DIM (0x05 << NCP5623_CMD_SHIFT) >>> +#define CMD_DOWNWARD_DIM (0x06 << NCP5623_CMD_SHIFT) >>> +#define CMD_DIM_STEP (0x07 << NCP5623_CMD_SHIFT) >>> + >>> +#define NCP5623_DATA_MASK GENMASK(NCP5623_CMD_SHIFT - 1, 0) >>> + >>> +#define NCP5623_CMD(cmd, data) (cmd | (data & NCP5623_DATA_MASK= )) >>> + > > [snip] > >>> + >>> +static int ncp5623_configure(struct device *dev, >>> + struct ncp5623_priv *priv) >>> +{ >>> + unsigned int i; >>> + unsigned int n; >>> + struct ncp5623_led *led; >>> + int err; >>> + >>> + /* Compute the value of ILED register to honor led_max_current= */ >>> + n =3D 2400 * priv->led_iref / priv->led_max_current + 1; >>> + if (n > NCP5623_MAX_CURRENT) >>> + n =3D NCP5623_MAX_CURRENT; >>> + n =3D NCP5623_MAX_CURRENT - n; >>> + >>> + dev_dbg(dev, "setting maximum current to %u uA\n", >>> + 2400 * priv->led_iref / (NCP5623_MAX_CURRENT - n)); >>> + >>> + err =3D ncp5623_send_cmd(priv, CMD_ILED, n); >>> + if (err < 0) { >>> + dev_err(dev, "cannot set the current\n"); >>> + return err; >>> + } >>> + >>> + /* Setup each individual LED */ >>> + for (i =3D 0; i < NCP5623_MAX_LEDS; i++) { >>> + led =3D &priv->leds[i]; >>> + >>> + if (!led->active) >>> + continue; >>> + >>> + led->priv =3D priv; >>> + led->led_no =3D i; >>> + led->ldev.brightness_set =3D ncp5623_brightness_set; >>> + led->ldev.max_brightness =3D NCP5623_MAX_STEPS - 1; >> >> max_brightness should be asserted according to led-max-microamp >> property. >> > > We can set two parameters on this chip: > > - The intensity of the current source (common to all LEDs) from 0 to > NCP5623_MAX_CURRENT (31) > - The PWM for each LED independently from 0 to NCP5623_MAX_STEPS-1 (3= 1) > > My understanding was to use the led-max-microamp property to set up t= he current > source so that even with a duty cycle of 100% (PWM=3D31) the LED cann= ot be > damaged. In this case, I think that is unnecessary to assert max_brig= htness, as > we are guaranteed by design that led-max-microamp will not be surpass= ed for any > value of the PWM. Would you suggest another approach? Yes, if step 31 reflects led-max-microamp value, then max_brightness should be 31, regardless of led-max-microamp value. >>> + INIT_WORK(&led->work, ncp5623_led_work); >> >> Please remove it and use brightness_set_blocking op. >> >>> + err =3D led_classdev_register(dev, &led->ldev); >> >> Use devm prefixed version. >> >>> + if (err < 0) { >>> + dev_err(dev, "couldn't register LED %s\n", >>> + led->ldev.name); >>> + goto exit; >>> + } >>> + } >>> + >>> + return 0; >>> + >>> +exit: >>> + ncp5623_destroy_devices(priv); >>> + return err; >>> +} >>> + > > --=20 Best regards, Jacek Anaszewski