On Wed, Aug 25, 2021 at 1:09 AM Daniel Dadap <ddadap@xxxxxxxxxx> wrote:
>
> A number of upcoming notebook computer designs drive the internal
> display panel's backlight PWM through the Embedded Controller (EC).
> This EC-based backlight control can be plumbed through to an ACPI
> "WMAA" method interface, which in turn can be wrapped by WMI with
> the GUID handle 603E9613-EF25-4338-A3D0-C46177516DB7.
>
> Add a new driver, aliased to the WMAA WMI GUID, to expose a sysfs
> backlight class driver to control backlight levels on systems with
> EC-driven backlights.
I tried to avoid repetition of the comments given by others.
So, mine below.
...
> +config WMAA_BACKLIGHT_WMI
> + tristate "ACPI WMAA Backlight Driver"
> + depends on ACPI_WMI
> + depends on BACKLIGHT_CLASS_DEVICE
> + help
> + This driver provides a sysfs backlight interface for notebook
> + systems which expose the WMAA ACPI method and an associated WMI
> + wrapper to drive LCD backlight levels through the system's
> + Embedded Controller.
Please, add a sentence to tell how the module will be called. There
are plenty of examples in the kernel.
...
> +struct wmaa_args {
> + u32 set;
> + u32 val;
> + u32 ret;
> + u32 ignored[3];
> +};
I guess this structure deserves a kernel doc.
...
> +static const struct wmi_device_id wmaa_backlight_wmi_id_table[] = {
> + { .guid_string = WMAA_WMI_GUID },
> + { },
No comma for termination.
> +};
...
> +static int wmaa_backlight_get_brightness(struct backlight_device *bd)
> +{
> + u32 level;
> + int ret;
> +
> + ret = wmaa_get_brightness(&level);
> + WARN_ON(ret != 0);
Why?
> + return ret == 0 ? level : 0;
> +}
...
> +static int wmaa_backlight_wmi_probe(struct wmi_device *w, const void *ctx)
> +{
> + struct backlight_properties props = {0};
{} is slightly better.
> + struct wmi_wmaa_priv *priv;
> + u32 source;
> + int ret;
> +
> + priv = devm_kmalloc(&w->dev, sizeof(*priv), GFP_KERNEL);
> + if(!priv)
> + return -ENOMEM;
> + wdev = w;
I'm wondering if it's possible to avoid having a global variable.
> + ret = wmaa_get_brightness_source(&source);
> + if (ret)
> + goto done;
> +
> + if (source != WMAA_SOURCE_EC) {
> + ret = -ENODEV;
> + goto done;
> + }
> +
> + // Register a backlight handler
> + props.type = BACKLIGHT_PLATFORM;
> + ret = wmaa_get_max_brightness(&props.max_brightness);
> + if (ret)
> + goto done;
> +
> + ret = wmaa_get_brightness(&props.brightness);
> + if (ret)
> + goto done;
> +
> + priv->backlight = backlight_device_register("wmaa_backlight",
> + NULL, NULL, &wmaa_backlight_ops, &props);
> + if (IS_ERR(priv->backlight))
> + return PTR_ERR(priv->backlight);
> +
> + dev_set_drvdata(&w->dev, priv);
> +done:
Useless. Return directly.
> + return ret;
> +}
...
> +static struct wmi_driver wmaa_backlight_wmi_driver = {
> + .driver = {
> + .name = "wmaa-backlight",
> + },
> + .probe = wmaa_backlight_wmi_probe,
> + .remove = wmaa_backlight_wmi_remove,
> + .id_table = wmaa_backlight_wmi_id_table,
> +};
> +
Redundant blank line.
> +module_wmi_driver(wmaa_backlight_wmi_driver);
...
> +
> +MODULE_ALIAS("wmi:"WMAA_WMI_GUID);
Can you move this closer to GUID? But I'm not sure what is the
preferred style. Hans?
--
With Best Regards,
Andy Shevchenko
