On Thu, 11 Apr 2013 13:24:50 -0700 Andrew Bresticker <abres...@chromium.org>
wrote:
> Platform LCD devices may need to do some device-specific
> initialization before they can be used (regulator or GPIO setup,
> for example), but currently the driver does not support any way of
> doing this. This patch adds a probe() callback to plat_lcd_data
> which platform LCD devices can set to indicate that device-specific
> initialization is needed.
>
> index 17a6b83..f46180e 100644
> --- a/drivers/video/backlight/platform_lcd.c
> +++ b/drivers/video/backlight/platform_lcd.c
> @@ -86,6 +86,12 @@ static int platform_lcd_probe(struct platform_device *pdev)
> return -EINVAL;
> }
>
> + if (pdata->probe) {
> + err = pdata->probe(pdata);
> + if (err)
> + return err;
> + }
> +
> plcd = devm_kzalloc(&pdev->dev, sizeof(struct platform_lcd),
> GFP_KERNEL);
> if (!plcd) {
> diff --git a/include/video/platform_lcd.h b/include/video/platform_lcd.h
> index ad3bdfe..23864b2 100644
> --- a/include/video/platform_lcd.h
> +++ b/include/video/platform_lcd.h
> @@ -15,6 +15,7 @@ struct plat_lcd_data;
> struct fb_info;
>
> struct plat_lcd_data {
> + int (*probe)(struct plat_lcd_data *);
> void (*set_power)(struct plat_lcd_data *, unsigned int power);
> int (*match_fb)(struct plat_lcd_data *, struct fb_info *);
> };
Sigh. I see that this entire interface has been lovingly undocumented.
It's an invitation for us to grow bugs, incompatibilities, leaks, etc.
Possible example: what happens if pdata->probe does some resource
allocation or device initialisation which should be backed out if, say,
platform_lcd_probe() later fails?
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