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Date: Fri, 3 May 2024 08:19:53 +0100
From: Lee Jones <lee@...nel.org>
To: git@...tzsch.eu
Cc: Pavel Machek <pavel@....cz>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Kees Cook <keescook@...omium.org>,
"Gustavo A. R. Silva" <gustavoars@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
linux-arm-msm@...r.kernel.org,
~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] leds: sy7802: Add support for Silergy SY7802
flash LED controller
On Thu, 11 Apr 2024, Lee Jones wrote:
> On Mon, 01 Apr 2024, André Apitzsch via B4 Relay wrote:
>
> > From: André Apitzsch <git@...tzsch.eu>
> >
> > Add support for SY7802 flash LED controller. It can support up to 1.8A
> > flash current.
>
> This is a very small commit message for a 500+ line change!
>
> Please, tell us more.
>
> > Signed-off-by: André Apitzsch <git@...tzsch.eu>
> > ---
> > drivers/leds/flash/Kconfig | 11 +
> > drivers/leds/flash/Makefile | 1 +
> > drivers/leds/flash/leds-sy7802.c | 532 +++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 544 insertions(+)
> >
> > diff --git a/drivers/leds/flash/Kconfig b/drivers/leds/flash/Kconfig
> > index 809b6d98bb3e..f39f0bfe6eef 100644
> > --- a/drivers/leds/flash/Kconfig
> > +++ b/drivers/leds/flash/Kconfig
> > @@ -121,4 +121,15 @@ config LEDS_SGM3140
> > This option enables support for the SGM3140 500mA Buck/Boost Charge
> > Pump LED Driver.
> >
> > +config LEDS_SY7802
> > + tristate "LED support for the Silergy SY7802"
> > + depends on I2C && OF
> > + depends on GPIOLIB
> > + select REGMAP_I2C
> > + help
> > + This option enables support for the SY7802 flash LED controller.
> > + SY7802 includes torch and flash functions with programmable current.
> > +
> > + This driver can be built as a module, it will be called "leds-sy7802".
> > +
> > endif # LEDS_CLASS_FLASH
> > diff --git a/drivers/leds/flash/Makefile b/drivers/leds/flash/Makefile
> > index 91d60a4b7952..48860eeced79 100644
> > --- a/drivers/leds/flash/Makefile
> > +++ b/drivers/leds/flash/Makefile
> > @@ -11,3 +11,4 @@ obj-$(CONFIG_LEDS_QCOM_FLASH) += leds-qcom-flash.o
> > obj-$(CONFIG_LEDS_RT4505) += leds-rt4505.o
> > obj-$(CONFIG_LEDS_RT8515) += leds-rt8515.o
> > obj-$(CONFIG_LEDS_SGM3140) += leds-sgm3140.o
> > +obj-$(CONFIG_LEDS_SY7802) += leds-sy7802.o
> > diff --git a/drivers/leds/flash/leds-sy7802.c b/drivers/leds/flash/leds-sy7802.c
> > new file mode 100644
> > index 000000000000..c03a571b0e08
> > --- /dev/null
> > +++ b/drivers/leds/flash/leds-sy7802.c
> > @@ -0,0 +1,532 @@
[...]
> > +static int sy7802_torch_brightness_set(struct led_classdev *lcdev, enum led_brightness level)
>
> s/level/brightness/
>
> > +{
> > + struct sy7802_led *led = container_of(lcdev, struct sy7802_led, flash.led_cdev);
> > + u32 led_enable_mask = led->led_no == SY7802_LED_JOINT ? SY7802_LEDS_MASK_ALL :
> > + SY7802_LEDS_MASK(led->led_no);
>
> Do all of the fancy multi-line assignment outside of the declaration block.
>
> > + u32 enable_mask = SY7802_MODE_MASK | led_enable_mask;
> > + u32 val = level ? led_enable_mask : SY7802_MODE_OFF;
> > + struct sy7802 *chip = led->chip;
> > + u32 curr;
>
> This is a temporary placeholder for fled_torch_used, right?
>
> fled_torch_used_tmp? Sometimes abbreviated to tmp.
>
> > + u32 mask;
>
> That's a lot of masks. Which one is this?
>
> > + int ret;
> > +
> > + mutex_lock(&chip->mutex);
> > +
> > + /*
> > + * There is only one set of flash control logic, and this flag is used to check if 'strobe'
>
> The ',' before 'and' is superfluous.
>
> > + * is currently being used.
> > + */
>
> Doesn't the variable name kind of imply this?
>
> > + if (chip->fled_strobe_used) {
> > + dev_warn(chip->dev, "Please disable strobe first [%d]\n", chip->fled_strobe_used);
>
> "Cannot set torch brightness whilst strobe is enabled"
>
> > + ret = -EBUSY;
> > + goto unlock;
> > + }
> > +
> > + if (level)
> > + curr = chip->fled_torch_used | BIT(led->led_no);
> > + else
> > + curr = chip->fled_torch_used & ~BIT(led->led_no);
> > +
> > + if (curr)
> > + val |= SY7802_MODE_TORCH;
> > +
> > + /* Torch needs to be disabled first to apply new brightness */
>
> "Disable touch to apply brightness"
>
> > + ret = regmap_update_bits(chip->regmap, SY7802_REG_ENABLE, SY7802_MODE_MASK,
> > + SY7802_MODE_OFF);
> > + if (ret)
> > + goto unlock;
> > +
> > + mask = led->led_no == SY7802_LED_JOINT ? SY7802_TORCH_CURRENT_MASK_ALL :
>
> Why not just use led->led_no in place of mask?
mask and led->led_no are assigned the same value from this point on.
> Easier to read if you drop SY7802_TORCH_CURRENT_MASK_ALL to its own line.
>
> > + SY7802_TORCH_CURRENT_MASK(led->led_no);
> > +
> > + /* Register expects brightness between 0 and MAX_BRIGHTNESS - 1 */
> > + if (level)
> > + level -= 1;
> > +
> > + level |= (level << SY7802_TORCH_CURRENT_SHIFT);
> > +
> > + ret = regmap_update_bits(chip->regmap, SY7802_REG_TORCH_BRIGHTNESS, mask, level);
So why not kill the single-use 'mask' variable and use a cast version of
led->led_no here instead?
> > + if (ret)
> > + goto unlock;
> > +
> > + ret = regmap_update_bits(chip->regmap, SY7802_REG_ENABLE, enable_mask, val);
> > + if (ret)
> > + goto unlock;
> > +
> > + chip->fled_torch_used = curr;
> > +
> > +unlock:
> > + mutex_unlock(&chip->mutex);
> > + return ret;
> > +}
--
Lee Jones [李琼斯]
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