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Date: Thu, 9 Jun 2022 18:57:24 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
Cc: Pavel Machek <pavel@....cz>, krzk+dt@...nel.org,
Rob Herring <robh+dt@...nel.org>,
Linux LED Subsystem <linux-leds@...r.kernel.org>,
devicetree <devicetree@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] leds: Add driver for the TLC5925 LED controller
On Thu, Jun 9, 2022 at 6:30 PM Jean-Jacques Hiblot
<jjhiblot@...phandler.com> wrote:
>
> The TLC5925 is a 16-channels constant-current LED sink driver.
> It is controlled via SPI but doesn't offer a register-based interface.
> Instead it contains a shift register and latches that convert the
> serial input into a parallel output.
Can you add Datasheet: tag here with the corresponding URL? Rationale
is to get a link to the datasheet by just browsing Git log without
browsing the source code, which will benefit via Web UIs.
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
...
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/leds.h>
> +#include <linux/err.h>
> +#include <linux/spi/spi.h>
> +#include <linux/property.h>
> +#include <linux/workqueue.h>
Keep it sorted?
...
> +struct single_led_priv {
> + int idx;
> + struct led_classdev cdev;
For pointer arithmetics it's better to swap these two members.
> +};
> +
> +struct tlc5925_leds_priv {
> + int max_num_leds;
> + u8 *state;
unsigned long? DECLARE_BITMAP() ?
> + spinlock_t lock;
> + struct single_led_priv leds[];
> +};
...
> + if (brightness)
> + priv->state[index / 8] |= (1 << (index % 8));
> + else
> + priv->state[index / 8] &= ~(1 << (index % 8));
assign_bit()
...
> + return spi_write(spi, priv->state, priv->max_num_leds / 8);
BITS_TO_BYTES() ?
...
> + count = device_get_child_node_count(dev);
> + if (!count) {
> + dev_err(dev, "no led defined.\n");
> + return -ENODEV;
return dev_err_probe(...);
here and everywhere in ->probe() and Co.
> + }
...
> + ret = device_property_read_u32_array(dev, "ti,shift-register-length",
> + &max_num_leds, 1);
Always an array of 1 element? call device_property_read_u32().
...
> + if (max_num_leds % 8) {
> + dev_err(dev, "'ti,shift-register-length' must be a multiple of 8\n");
> + return -EINVAL;
> + }
Is this really fatal? I would rather issue a warning and go on if it
has at least 8 there. So the idea is to use a minimum that holds
multiple of 8.
...
> + /* Assert all the OE/ lines */
> + gpios = devm_gpiod_get_array(dev, "output-enable-b", GPIOD_OUT_LOW);
> + if (IS_ERR(gpios)) {
> + dev_err(dev, "Unable to get the 'output-enable-b' gpios\n");
> + return PTR_ERR(gpios);
> + }
You have to use dev_err_probe() here, otherwise it will spam logs a
lot in case of deferred probe.
...
> + priv->state = devm_kzalloc(dev, DIV_ROUND_UP(max_num_leds, 8), GFP_KERNEL);
devm_bitmap_zalloc()
...
> + device_for_each_child_node(dev, child) {
> + struct led_init_data init_data = {.fwnode = child};
Missed spaces.
> + struct led_classdev *cdev;
> + u32 idx;
> +
> + ret = fwnode_property_read_u32_array(child, "reg", &idx, 1);
fwnode_property_read_u32()
> + if (ret || idx >= max_num_leds) {
> + dev_err(dev, "%s: invalid reg value. Ignoring.\n",
> + fwnode_get_name(child));
> + fwnode_handle_put(child);
> + continue;
Either dev_warn + continue, or dev_err + return dev_err_probe().
> + }
> +
> + count--;
> + priv->leds[count].idx = idx;
> + cdev = &(priv->leds[count].cdev);
> + cdev->brightness = LED_OFF;
> + cdev->max_brightness = 1;
> + cdev->brightness_set_blocking = tlc5925_brightness_set_blocking;
> +
> + ret = devm_led_classdev_register_ext(dev, cdev, &init_data);
> + if (ret) {
Ditto.
> + dev_err(dev, "%s: cannot create LED device.\n",
> + fwnode_get_name(child));
> + fwnode_handle_put(child);
> + continue;
> + }
> + }
...
> +static const struct of_device_id tlc5925_dt_ids[] = {
> + { .compatible = "ti,tlc5925", },
> + {},
No comma for terminator entry.
> +};
Where is the MODULE_DEVICE_TABLE() for this one?
...
> +
No need for this blank line.
> +module_spi_driver(tlc5925_driver);
--
With Best Regards,
Andy Shevchenko
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