Re: [PATCH v1 1/4] backlight: hx8357: Make use of device properties

Javier Martinez Canillas
2024-01-15T08:20:51Z

Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:

Hello Andy,

> Convert the module to be property provider agnostic and allow
> it to be used on non-OF platforms.
>
> Include mod_devicetable.h explicitly to replace the dropped of.h
> which included mod_devicetable.h indirectly.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> drivers/video/backlight/hx8357.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/video/backlight/hx8357.c b/drivers/video/backlight/hx8357.c
> index bf18337ff0c2..c7fd10d55c5d 100644
> --- a/drivers/video/backlight/hx8357.c
> +++ b/drivers/video/backlight/hx8357.c
> @@ -8,9 +8,9 @@
> #include <linux/delay.h>
> #include <linux/gpio/consumer.h>
> #include <linux/lcd.h>
> +#include <linux/mod_devicetable.h>
> #include <linux/module.h>
> -#include <linux/of.h>
> -#include <linux/of_device.h>
> +#include <linux/property.h>
> #include <linux/spi/spi.h>
>
> #define HX8357_NUM_IM_PINS 3
> @@ -564,6 +564,8 @@ static struct lcd_ops hx8357_ops = {
> .get_power = hx8357_get_power,
> };
>
> +typedef int (*hx8357_init)(struct lcd_device *);
> +

This kind of typedef usage is frowned upon in the Linux coding style [0]
(per my understanding at least) and indeed in my opinion it makes harder
to grep.

[0] https://www.kernel.org/doc/Documentation/process/coding-style.rst

> static const struct of_device_id hx8357_dt_ids[] = {
> {
> .compatible = "himax,hx8357",
> @@ -582,7 +584,7 @@ static int hx8357_probe(struct spi_device *spi)
> struct device *dev = &spi->dev;
> struct lcd_device *lcdev;
> struct hx8357_data *lcd;
> - const struct of_device_id *match;
> + hx8357_init init;
> int i, ret;
>
> lcd = devm_kzalloc(&spi->dev, sizeof(*lcd), GFP_KERNEL);
> @@ -597,8 +599,8 @@ static int hx8357_probe(struct spi_device *spi)
>
> lcd->spi = spi;
>
> - match = of_match_device(hx8357_dt_ids, &spi->dev);
> - if (!match || !match->data)
> + init = device_get_match_data(dev);
> + if (!init)
> return -EINVAL;
>
> lcd->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> @@ -627,7 +629,7 @@ static int hx8357_probe(struct spi_device *spi)
>
> hx8357_lcd_reset(lcdev);
>
> - ret = ((int (*)(struct lcd_device *))match->data)(lcdev);

This is what I mean, before it was clear what was stored in match->data.
But after you changes, what is returned by the device_get_match_data()
function is opaque and you need to look at the typedef hx8357_init to
figure that out.

No strong opinion though and I see other drivers doing the same (but no
other driver in drivers/video/backlight).

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>

--
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat