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Message-ID: <a1adbe50-3400-fd10-1856-8c1d0ed82276@sholland.org>
Date:   Tue, 17 Oct 2023 19:38:43 -0500
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Subject: Re: [RESEND PATCH v7 2/5] leds: sun50i-a100: New driver for the A100
 LED controller
Content-Language: en-US
To:     Lee Jones <lee@kernel.org>
Cc:     Pavel Machek <pavel@ucw.cz>, linux-leds@vger.kernel.org,
        Chen-Yu Tsai <wens@csie.org>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev
References: <20221231235541.13568-1-samuel@sholland.org>
 <20221231235541.13568-3-samuel@sholland.org>
 <20230316133422.GM9667@google.com>
From:   Samuel Holland <samuel@sholland.org>
In-Reply-To: <20230316133422.GM9667@google.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 3/16/23 08:34, Lee Jones wrote:
> On Sat, 31 Dec 2022, Samuel Holland wrote:
> 
>> Some Allwinner sunxi SoCs, starting with the A100, contain an LED
>> controller designed to drive RGB LED pixels. Add a driver for it using
>> the multicolor LED framework, and with LEDs defined in the device tree.
>>
>> Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
>> Signed-off-by: Samuel Holland <samuel@sholland.org>
>> ---
>>
>> Changes in v7:
>>  - Use DEFINE_SIMPLE_DEV_PM_OPS
>>
>> Changes in v5:
>>  - Rename the driver R329 -> A100, since that is the actual original
>>    implementation
>>
>> Changes in v4:
>>  - Depend on LEDS_CLASS_MULTICOLOR
>>
>> Changes in v3:
>>  - Added vendor prefix to timing/format properties
>>  - Renamed "format" property to "pixel-format" for clarity
>>  - Dropped "vled-supply" as it is unrelated to the controller hardware
>>  - Changed "writesl" to "iowrite32_rep" so the driver builds on hppa
>>
>> Changes in v2:
>>  - Renamed from sunxi-ledc to sun50i-r329-ledc
>>  - Added missing "static" to functions/globals as reported by 0day bot
>>
>>  drivers/leds/Kconfig            |   9 +
>>  drivers/leds/Makefile           |   1 +
>>  drivers/leds/leds-sun50i-a100.c | 555 ++++++++++++++++++++++++++++++++
>>  3 files changed, 565 insertions(+)
>>  create mode 100644 drivers/leds/leds-sun50i-a100.c
> 
> Nice driver.  Just some nits below.

Thanks for the review!

>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>> index 499d0f215a8b..4f4c515ed7d7 100644
>> --- a/drivers/leds/Kconfig
>> +++ b/drivers/leds/Kconfig
>> @@ -281,6 +281,15 @@ config LEDS_COBALT_RAQ
>>  	help
>>  	  This option enables support for the Cobalt Raq series LEDs.
>>
>> +config LEDS_SUN50I_A100
>> +	tristate "LED support for Allwinner A100 RGB LED controller"
>> +	depends on LEDS_CLASS_MULTICOLOR && OF
>> +	depends on ARCH_SUNXI || COMPILE_TEST
>> +	help
>> +	  This option enables support for the RGB LED controller found
>> +	  in some Allwinner sunxi SoCs, includeing A100, R329, and D1.
>> +	  It uses a one-wire interface to control up to 1024 LEDs.
> 
> Did you run spellcheck on this?

I will fix the spelling and style issues in the next version.

>>  config LEDS_SUNFIRE
>>  	tristate "LED support for SunFire servers."
>>  	depends on LEDS_CLASS
>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
>> index 4fd2f92cd198..a6ee3f5cf7be 100644
>> --- a/drivers/leds/Makefile
>> +++ b/drivers/leds/Makefile
>> @@ -76,6 +76,7 @@ obj-$(CONFIG_LEDS_PWM)			+= leds-pwm.o
>>  obj-$(CONFIG_LEDS_REGULATOR)		+= leds-regulator.o
>>  obj-$(CONFIG_LEDS_S3C24XX)		+= leds-s3c24xx.o
>>  obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
>> +obj-$(CONFIG_LEDS_SUN50I_A100)		+= leds-sun50i-a100.o
>>  obj-$(CONFIG_LEDS_SUNFIRE)		+= leds-sunfire.o
>>  obj-$(CONFIG_LEDS_SYSCON)		+= leds-syscon.o
>>  obj-$(CONFIG_LEDS_TCA6507)		+= leds-tca6507.o
>> diff --git a/drivers/leds/leds-sun50i-a100.c b/drivers/leds/leds-sun50i-a100.c
>> new file mode 100644
>> index 000000000000..30fa9be2cf2d
>> --- /dev/null
>> +++ b/drivers/leds/leds-sun50i-a100.c
>> @@ -0,0 +1,555 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +//
>> +// Copyright (c) 2021-2022 Samuel Holland <samuel@sholland.org>
> 
> Please update.
> 
>> +// Partly based on drivers/leds/leds-turris-omnia.c, which is:
>> +//     Copyright (c) 2020 by Marek Behún <kabel@kernel.org>
>> +//
> 
> What is this line commenting?
> 
> Could you please re-do this header to use C-style comments please.
> 
>> +#include <linux/clk.h>
>> +#include <linux/dma-mapping.h>
>> +#include <linux/dmaengine.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/led-class-multicolor.h>
>> +#include <linux/leds.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm.h>
>> +#include <linux/reset.h>
>> +#include <linux/spinlock.h>
>> +
>> +#define LEDC_CTRL_REG			0x0000
>> +#define LEDC_CTRL_REG_DATA_LENGTH		(0x1fff << 16)
>> +#define LEDC_CTRL_REG_RGB_MODE			(0x7 << 6)
>> +#define LEDC_CTRL_REG_LEDC_EN			BIT(0)
>> +#define LEDC_T01_TIMING_CTRL_REG	0x0004
>> +#define LEDC_T01_TIMING_CTRL_REG_T1H		(0x3f << 21)
>> +#define LEDC_T01_TIMING_CTRL_REG_T1L		(0x1f << 16)
>> +#define LEDC_T01_TIMING_CTRL_REG_T0H		(0x1f << 6)
>> +#define LEDC_T01_TIMING_CTRL_REG_T0L		(0x3f << 0)
>> +#define LEDC_RESET_TIMING_CTRL_REG	0x000c
>> +#define LEDC_RESET_TIMING_CTRL_REG_LED_NUM	(0x3ff << 0)
>> +#define LEDC_DATA_REG			0x0014
>> +#define LEDC_DMA_CTRL_REG		0x0018
>> +#define LEDC_DMA_CTRL_REG_FIFO_TRIG_LEVEL	(0x1f << 0)
>> +#define LEDC_INT_CTRL_REG		0x001c
>> +#define LEDC_INT_CTRL_REG_GLOBAL_INT_EN		BIT(5)
>> +#define LEDC_INT_CTRL_REG_FIFO_CPUREQ_INT_EN	BIT(1)
>> +#define LEDC_INT_CTRL_REG_TRANS_FINISH_INT_EN	BIT(0)
>> +#define LEDC_INT_STS_REG		0x0020
>> +#define LEDC_INT_STS_REG_FIFO_CPUREQ_INT	BIT(1)
>> +#define LEDC_INT_STS_REG_TRANS_FINISH_INT	BIT(0)
>> +
>> +#define LEDC_FIFO_DEPTH			32
>> +#define LEDC_MAX_LEDS			1024
>> +
>> +#define LEDS_TO_BYTES(n)		((n) * sizeof(u32))
>> +
>> +struct sun50i_a100_ledc_led {
> 
> Is this information likely to change on a per-LED basis?

Yes, this controller is designed to drive strips of
individually-addressible RGB LEDs (WS2812 or similar). Each RGB LED is
independent.

>> +	struct led_classdev_mc mc_cdev;
>> +	struct mc_subled subled_info[3];
> 
> What is 3?

The three colors (R/G/B) per multicolor LED.

>> +};
>> +
>> +#define to_ledc_led(mc) container_of(mc, struct sun50i_a100_ledc_led, mc_cdev)
>> +
>> +struct sun50i_a100_ledc_timing {
>> +	u32 t0h_ns;
>> +	u32 t0l_ns;
>> +	u32 t1h_ns;
>> +	u32 t1l_ns;
>> +	u32 treset_ns;
>> +};
>> +
>> +struct sun50i_a100_ledc {
>> +	struct device *dev;
>> +	void __iomem *base;
>> +	struct clk *bus_clk;
>> +	struct clk *mod_clk;
>> +	struct reset_control *reset;
>> +
>> +	u32 *buffer;
>> +	struct dma_chan *dma_chan;
>> +	dma_addr_t dma_handle;
>> +	int pio_length;
>> +	int pio_offset;
>> +
>> +	spinlock_t lock;
>> +	int next_length;
>> +	bool xfer_active;
>> +
>> +	u32 format;
>> +	struct sun50i_a100_ledc_timing timing;
>> +
>> +	int num_leds;
>> +	struct sun50i_a100_ledc_led leds[];
>> +};
>> +
>> +static int sun50i_a100_ledc_dma_xfer(struct sun50i_a100_ledc *priv, int length)
>> +{
>> +	struct dma_async_tx_descriptor *desc;
>> +	dma_cookie_t cookie;
>> +
>> +	desc = dmaengine_prep_slave_single(priv->dma_chan, priv->dma_handle,
>> +					   LEDS_TO_BYTES(length),
>> +					   DMA_MEM_TO_DEV, 0);
>> +	if (!desc)
>> +		return -ENOMEM;
>> +
>> +	cookie = dmaengine_submit(desc);
>> +	if (dma_submit_error(cookie))
>> +		return -EIO;
>> +
>> +	dma_async_issue_pending(priv->dma_chan);
>> +
>> +	return 0;
>> +}
>> +
>> +static void sun50i_a100_ledc_pio_xfer(struct sun50i_a100_ledc *priv, int length)
>> +{
>> +	u32 burst, offset, val;
>> +
>> +	if (length) {
>> +		/* New transfer (FIFO is empty). */
>> +		offset = 0;
>> +		burst  = min(length, LEDC_FIFO_DEPTH);
>> +	} else {
>> +		/* Existing transfer (FIFO is half-full). */
>> +		length = priv->pio_length;
>> +		offset = priv->pio_offset;
>> +		burst  = min(length, LEDC_FIFO_DEPTH / 2);
> 
> Didn't we already establish that length was 0?

Yes, and then we set it to the length of the existing partial transfer
two lines above here. I can split out the parameter from `length` for
clarity.

>> +	}
>> +
>> +	iowrite32_rep(priv->base + LEDC_DATA_REG, priv->buffer + offset, burst);
>> +
>> +	if (burst < length) {
>> +		priv->pio_length = length - burst;
>> +		priv->pio_offset = offset + burst;
>> +
>> +		if (!offset) {
>> +			val = readl(priv->base + LEDC_INT_CTRL_REG);
>> +			val |= LEDC_INT_CTRL_REG_FIFO_CPUREQ_INT_EN;
>> +			writel(val, priv->base + LEDC_INT_CTRL_REG);
>> +		}
>> +	} else {
>> +		/* Disable the request IRQ once all data is written. */
>> +		val = readl(priv->base + LEDC_INT_CTRL_REG);
>> +		val &= ~LEDC_INT_CTRL_REG_FIFO_CPUREQ_INT_EN;
>> +		writel(val, priv->base + LEDC_INT_CTRL_REG);
>> +	}
>> +}
>> +
>> +static void sun50i_a100_ledc_start_xfer(struct sun50i_a100_ledc *priv,
>> +					int length)
>> +{
>> +	u32 val;
>> +
>> +	dev_dbg(priv->dev, "Updating %d LEDs\n", length);
> 
> How useful is this, really?
> 
> Could you consider removing it?

It was helpful to verify the queued transfer went out. I will remove it.

>> +	val = readl(priv->base + LEDC_CTRL_REG);
>> +	val &= ~LEDC_CTRL_REG_DATA_LENGTH;
>> +	val |= length << 16 | LEDC_CTRL_REG_LEDC_EN;
> 
> Why 16?  Please consider defining all magic numbers.
> 
>   BLAH_BLAH_SHIFT ?
> 
>> +	writel(val, priv->base + LEDC_CTRL_REG);
>> +
>> +	if (length > LEDC_FIFO_DEPTH) {
>> +		int ret = sun50i_a100_ledc_dma_xfer(priv, length);
> 
> Looks odd.  It's way more common to separate the call from the declaration.
> 
>> +		if (!ret)
>> +			return;
>> +
>> +		dev_warn(priv->dev, "Failed to set up DMA: %d\n", ret);
> 
> This looks like an error.
> 
> Please tell the user we're falling back to PIO.

Do you mean that I should change the message to mention that, or
something more?

>> +	}
>> +
>> +	sun50i_a100_ledc_pio_xfer(priv, length);
>> +}
>> +
>> +static irqreturn_t sun50i_a100_ledc_irq(int irq, void *dev_id)
>> +{
>> +	struct sun50i_a100_ledc *priv = dev_id;
> 
> This is clearly not a def_id.  'data' looks like a common alternative.
> 
>> +	u32 val;
>> +
>> +	val = readl(priv->base + LEDC_INT_STS_REG);
> 
> 'val' is a terrible variable name.  'status'?
> 
>> +	if (val & LEDC_INT_STS_REG_TRANS_FINISH_INT) {
>> +		int next_length;
>> +
>> +		/* Start the next transfer if needed. */
>> +		spin_lock(&priv->lock);
>> +		next_length = priv->next_length;
>> +		if (next_length)
>> +			priv->next_length = 0;
>> +		else
>> +			priv->xfer_active = false;
>> +		spin_unlock(&priv->lock);
>> +
>> +		if (next_length)
>> +			sun50i_a100_ledc_start_xfer(priv, next_length);
>> +	} else if (val & LEDC_INT_STS_REG_FIFO_CPUREQ_INT) {
>> +		/* Continue the current transfer. */
>> +		sun50i_a100_ledc_pio_xfer(priv, 0);
>> +	}
>> +
>> +	writel(val, priv->base + LEDC_INT_STS_REG);
> 
> Did 'val' change?  If this is intentional, perhaps a comment to clarify.

The IRQ status bits are write-1-to-clear. I will add a comment.

>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static void sun50i_a100_ledc_brightness_set(struct led_classdev *cdev,
>> +					    enum led_brightness brightness)
>> +{
>> +	struct sun50i_a100_ledc *priv = dev_get_drvdata(cdev->dev->parent);
>> +	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
>> +	struct sun50i_a100_ledc_led *led = to_ledc_led(mc_cdev);
>> +	int addr = led - priv->leds;
> 
> Not really an address is it?  'offset' or something better?

It is the address of the LED on the one-wire bus. But in this context,
`offset` makes sense too, so I'll change it.

>> +	unsigned long flags;
>> +	bool xfer_active;
>> +	int next_length;
>> +
>> +	led_mc_calc_color_components(mc_cdev, brightness);
>> +
>> +	priv->buffer[addr] = led->subled_info[0].brightness << 16 |
>> +			     led->subled_info[1].brightness <<  8 |
>> +			     led->subled_info[2].brightness;
>> +
>> +	dev_dbg(priv->dev, "LED %d -> #%06x\n", addr, priv->buffer[addr]);
> 
> As above.
> 
>> +	spin_lock_irqsave(&priv->lock, flags);
>> +	next_length = max(priv->next_length, addr + 1);
>> +	xfer_active = priv->xfer_active;
>> +	if (xfer_active)
>> +		priv->next_length = next_length;
>> +	else
>> +		priv->xfer_active = true;
>> +	spin_unlock_irqrestore(&priv->lock, flags);
> 
> Cramped code is not easy to read.  Please consider some '\n's.
> 
>> +	if (!xfer_active)
>> +		sun50i_a100_ledc_start_xfer(priv, next_length);
>> +}
>> +
>> +static const char *const sun50i_a100_ledc_formats[] = {
>> +	"rgb",
>> +	"rbg",
>> +	"grb",
>> +	"gbr",
>> +	"brg",
>> +	"bgr",
>> +};
>> +
>> +static int sun50i_a100_ledc_parse_format(const struct device_node *np,
>> +					 struct sun50i_a100_ledc *priv)
>> +{
>> +	const char *format = "grb";
>> +	u32 i;
>> +
>> +	of_property_read_string(np, "allwinner,pixel-format", &format);
>> +
>> +	for (i = 0; i < ARRAY_SIZE(sun50i_a100_ledc_formats); ++i) {
> 
> Does the pre-increment hold any significance?

No, I will update it.

> If not, please use the more common implementation of post-incrementing.
> 
>> +		if (!strcmp(format, sun50i_a100_ledc_formats[i])) {
>> +			priv->format = i;
>> +			return 0;
>> +		}
>> +	}
>> +
>> +	dev_err(priv->dev, "Bad pixel format '%s'\n", format);
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static void sun50i_a100_ledc_set_format(struct sun50i_a100_ledc *priv)
>> +{
>> +	u32 val;
>> +
>> +	val = readl(priv->base + LEDC_CTRL_REG);
>> +	val &= ~LEDC_CTRL_REG_RGB_MODE;
>> +	val |= priv->format << 6;
>> +	writel(val, priv->base + LEDC_CTRL_REG);
>> +}
>> +
>> +static const struct sun50i_a100_ledc_timing sun50i_a100_ledc_default_timing = {
>> +	.t0h_ns = 336,
>> +	.t0l_ns = 840,
>> +	.t1h_ns = 882,
>> +	.t1l_ns = 294,
>> +	.treset_ns = 300000,
>> +};
>> +
>> +static int sun50i_a100_ledc_parse_timing(const struct device_node *np,
>> +					 struct sun50i_a100_ledc *priv)
>> +{
>> +	struct sun50i_a100_ledc_timing *timing = &priv->timing;
>> +
>> +	*timing = sun50i_a100_ledc_default_timing;
>> +
>> +	of_property_read_u32(np, "allwinner,t0h-ns", &timing->t0h_ns);
>> +	of_property_read_u32(np, "allwinner,t0l-ns", &timing->t0l_ns);
>> +	of_property_read_u32(np, "allwinner,t1h-ns", &timing->t1h_ns);
>> +	of_property_read_u32(np, "allwinner,t1l-ns", &timing->t1l_ns);
>> +	of_property_read_u32(np, "allwinner,treset-ns", &timing->treset_ns);
>> +
>> +	return 0;
>> +}
>> +
>> +static void sun50i_a100_ledc_set_timing(struct sun50i_a100_ledc *priv)
>> +{
>> +	const struct sun50i_a100_ledc_timing *timing = &priv->timing;
>> +	unsigned long mod_freq = clk_get_rate(priv->mod_clk);
>> +	u32 cycle_ns = NSEC_PER_SEC / mod_freq;
>> +	u32 val;
> 
> 'timing'
> 
>> +	val = (timing->t1h_ns / cycle_ns) << 21 |
>> +	      (timing->t1l_ns / cycle_ns) << 16 |
>> +	      (timing->t0h_ns / cycle_ns) <<  6 |
>> +	      (timing->t0l_ns / cycle_ns);
>> +	writel(val, priv->base + LEDC_T01_TIMING_CTRL_REG);
>> +
>> +	val = (timing->treset_ns / cycle_ns) << 16 |
>> +	      (priv->num_leds - 1);
>> +	writel(val, priv->base + LEDC_RESET_TIMING_CTRL_REG);
>> +}
>> +
>> +static int sun50i_a100_ledc_resume(struct device *dev)
>> +{
>> +	struct sun50i_a100_ledc *priv = dev_get_drvdata(dev);
>> +	u32 val;
>> +	int ret;
> 
> 'control'
> 
>> +	ret = reset_control_deassert(priv->reset);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = clk_prepare_enable(priv->bus_clk);
>> +	if (ret)
>> +		goto err_assert_reset;
>> +
>> +	ret = clk_prepare_enable(priv->mod_clk);
>> +	if (ret)
>> +		goto err_disable_bus_clk;
>> +
>> +	sun50i_a100_ledc_set_format(priv);
>> +	sun50i_a100_ledc_set_timing(priv);
>> +
>> +	/* The trigger level must be at least the burst length. */
>> +	val = readl(priv->base + LEDC_DMA_CTRL_REG);
>> +	val &= ~LEDC_DMA_CTRL_REG_FIFO_TRIG_LEVEL;
>> +	val |= LEDC_FIFO_DEPTH / 2;
>> +	writel(val, priv->base + LEDC_DMA_CTRL_REG);
>> +
>> +	val = LEDC_INT_CTRL_REG_GLOBAL_INT_EN |
>> +	      LEDC_INT_CTRL_REG_TRANS_FINISH_INT_EN;
>> +	writel(val, priv->base + LEDC_INT_CTRL_REG);
>> +
>> +	return 0;
>> +
>> +err_disable_bus_clk:
>> +	clk_disable_unprepare(priv->bus_clk);
>> +err_assert_reset:
>> +	reset_control_assert(priv->reset);
>> +
>> +	return ret;
>> +}
>> +
>> +static int sun50i_a100_ledc_suspend(struct device *dev)
>> +{
>> +	struct sun50i_a100_ledc *priv = dev_get_drvdata(dev);
>> +
>> +	clk_disable_unprepare(priv->mod_clk);
>> +	clk_disable_unprepare(priv->bus_clk);
>> +	reset_control_assert(priv->reset);
>> +
>> +	return 0;
>> +}
>> +
>> +static void sun50i_a100_ledc_dma_cleanup(void *data)
>> +{
>> +	struct sun50i_a100_ledc *priv = data;
>> +	struct device *dma_dev = dmaengine_get_dma_device(priv->dma_chan);
> 
> What happens if this is NULL or an error?

At this point, we successfully acquired a DMA channel, so I don't think
it can be. That said, it wouldn't hurt to make the driver work without
DMA at all, for if the SoC doesn't hook up the LED controller to the DMA
engine.

>> +	if (priv->buffer)
>> +		dma_free_wc(dma_dev, LEDS_TO_BYTES(priv->num_leds),
>> +			    priv->buffer, priv->dma_handle);
> 
> '\n'
> 
>> +	dma_release_channel(priv->dma_chan);
>> +}
>> +
>> +static int sun50i_a100_ledc_probe(struct platform_device *pdev)
>> +{
>> +	const struct device_node *np = pdev->dev.of_node;
>> +	struct dma_slave_config dma_cfg = {};
>> +	struct led_init_data init_data = {};
>> +	struct device *dev = &pdev->dev;
>> +	struct device_node *child;
>> +	struct sun50i_a100_ledc *priv;
>> +	struct resource *mem;
>> +	int count, irq, ret;
>> +
>> +	count = of_get_available_child_count(np);
>> +	if (!count)
>> +		return -ENODEV;
> 
> '\n'
> 
>> +	if (count > LEDC_MAX_LEDS) {
>> +		dev_err(dev, "Too many LEDs! (max is %d)\n", LEDC_MAX_LEDS);
>> +		return -EINVAL;
>> +	}
>> +
>> +	priv = devm_kzalloc(dev, struct_size(priv, leds, count), GFP_KERNEL);
>> +	if (!priv)
>> +		return -ENOMEM;
>> +
>> +	priv->dev = dev;
>> +	priv->num_leds = count;
>> +	spin_lock_init(&priv->lock);
>> +	dev_set_drvdata(dev, priv);
>> +
>> +	ret = sun50i_a100_ledc_parse_format(np, priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = sun50i_a100_ledc_parse_timing(np, priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);
>> +	if (IS_ERR(priv->base))
>> +		return PTR_ERR(priv->base);
>> +
>> +	priv->bus_clk = devm_clk_get(dev, "bus");
>> +	if (IS_ERR(priv->bus_clk))
>> +		return PTR_ERR(priv->bus_clk);
>> +
>> +	priv->mod_clk = devm_clk_get(dev, "mod");
>> +	if (IS_ERR(priv->mod_clk))
>> +		return PTR_ERR(priv->mod_clk);
>> +
>> +	priv->reset = devm_reset_control_get_exclusive(dev, NULL);
>> +	if (IS_ERR(priv->reset))
>> +		return PTR_ERR(priv->reset);
>> +
>> +	priv->dma_chan = dma_request_chan(dev, "tx");
>> +	if (IS_ERR(priv->dma_chan))
>> +		return PTR_ERR(priv->dma_chan);
>> +
>> +	ret = devm_add_action_or_reset(dev, sun50i_a100_ledc_dma_cleanup, priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dma_cfg.dst_addr	= mem->start + LEDC_DATA_REG;
>> +	dma_cfg.dst_addr_width	= DMA_SLAVE_BUSWIDTH_4_BYTES;
>> +	dma_cfg.dst_maxburst	= LEDC_FIFO_DEPTH / 2;
> 
> '\n'
> 
>> +	ret = dmaengine_slave_config(priv->dma_chan, &dma_cfg);
>> +	if (ret)
>> +		return ret;
>> +
>> +	priv->buffer = dma_alloc_wc(dmaengine_get_dma_device(priv->dma_chan),
>> +				    LEDS_TO_BYTES(priv->num_leds),
>> +				    &priv->dma_handle, GFP_KERNEL);
>> +	if (!priv->buffer)
>> +		return -ENOMEM;
>> +
>> +	irq = platform_get_irq(pdev, 0);
>> +	if (irq < 0)
>> +		return irq;
>> +
>> +	ret = devm_request_irq(dev, irq, sun50i_a100_ledc_irq,
>> +			       0, dev_name(dev), priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = sun50i_a100_ledc_resume(dev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	for_each_available_child_of_node(np, child) {
>> +		struct sun50i_a100_ledc_led *led;
>> +		struct led_classdev *cdev;
>> +		u32 addr, color;
>> +
>> +		ret = of_property_read_u32(child, "reg", &addr);
>> +		if (ret || addr >= count) {
>> +			dev_err(dev, "LED 'reg' values must be from 0 to %d\n",
> 
> Doesn't sounds like an address.

The one-wire protocol involves the first LED responding to the first 24
bits of the transfer, then forwarding the rest to the next LED. The
address is the ordinal position in the chain. So I don't think there is
any reason to have gaps in the addresses--the LEDs would still have to
physically be there, but you would not be able to control them. That
said, the driver doesn't need to enforce this, so I can remove the check.

>> +				priv->num_leds - 1);
> 
> 100-chars - no need to wrap.
> 
> Please apply this everywhere.
> 
>> +			ret = -EINVAL;
>> +			goto err_put_child;
>> +		}
>> +
>> +		ret = of_property_read_u32(child, "color", &color);
>> +		if (ret || color != LED_COLOR_ID_RGB) {
>> +			dev_err(dev, "LED 'color' must be LED_COLOR_ID_RGB\n");
> 
> Then why even provide the option?

It is required by the leds-class-multicolor.yaml binding.

>> +			ret = -EINVAL;
>> +			goto err_put_child;
>> +		}
>> +
>> +		led = &priv->leds[addr];
>> +
>> +		led->subled_info[0].color_index = LED_COLOR_ID_RED;
>> +		led->subled_info[0].channel = 0;
>> +		led->subled_info[1].color_index = LED_COLOR_ID_GREEN;
>> +		led->subled_info[1].channel = 1;
>> +		led->subled_info[2].color_index = LED_COLOR_ID_BLUE;
>> +		led->subled_info[2].channel = 2;
>> +
>> +		led->mc_cdev.num_colors = ARRAY_SIZE(led->subled_info);
>> +		led->mc_cdev.subled_info = led->subled_info;
>> +
>> +		cdev = &led->mc_cdev.led_cdev;
>> +		cdev->max_brightness = U8_MAX;
>> +		cdev->brightness_set = sun50i_a100_ledc_brightness_set;
>> +
>> +		init_data.fwnode = of_fwnode_handle(child);
>> +
>> +		ret = devm_led_classdev_multicolor_register_ext(dev,
>> +								&led->mc_cdev,
>> +								&init_data);
>> +		if (ret) {
>> +			dev_err(dev, "Failed to register LED %u: %d\n",
> 
> "multicolor LED"
> 
>> +				addr, ret);
>> +			goto err_put_child;
>> +		}
>> +	}
>> +
>> +	dev_info(dev, "Registered %d LEDs\n", priv->num_leds);
>> +
>> +	return 0;
>> +
>> +err_put_child:
>> +	of_node_put(child);
>> +	sun50i_a100_ledc_suspend(&pdev->dev);
>> +
>> +	return ret;
>> +}
>> +
>> +static int sun50i_a100_ledc_remove(struct platform_device *pdev)
>> +{
>> +	sun50i_a100_ledc_suspend(&pdev->dev);
>> +
>> +	return 0;
> 
> return sun50i_a100_ledc_suspend(&pdev->dev);
> 
>> +}
>> +
>> +static void sun50i_a100_ledc_shutdown(struct platform_device *pdev)
>> +{
>> +	sun50i_a100_ledc_suspend(&pdev->dev);
>> +}
>> +
>> +static const struct of_device_id sun50i_a100_ledc_of_match[] = {
>> +	{ .compatible = "allwinner,sun50i-a100-ledc" },
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(of, sun50i_a100_ledc_of_match);
>> +
>> +static DEFINE_SIMPLE_DEV_PM_OPS(sun50i_a100_ledc_pm,
>> +				sun50i_a100_ledc_suspend,
>> +				sun50i_a100_ledc_resume);
>> +
>> +static struct platform_driver sun50i_a100_ledc_driver = {
>> +	.probe		= sun50i_a100_ledc_probe,
>> +	.remove		= sun50i_a100_ledc_remove,
>> +	.shutdown	= sun50i_a100_ledc_shutdown,
>> +	.driver		= {
>> +		.name		= "sun50i-a100-ledc",
>> +		.of_match_table	= sun50i_a100_ledc_of_match,
>> +		.pm		= pm_ptr(&sun50i_a100_ledc_pm),
>> +	},
>> +};
>> +module_platform_driver(sun50i_a100_ledc_driver);
>> +
>> +MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
>> +MODULE_DESCRIPTION("Allwinner A100 LED controller driver");
>> +MODULE_LICENSE("GPL");
>> --
>> 2.37.4
>>
> 
> --
> Lee Jones [李琼斯]