linux-kernel - Re: [PATCH 1/2] video: ssd1307fb: Print PWM period using 64-bit format specifier

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Date:   Wed, 17 Jun 2020 09:18:34 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Lee Jones <lee.jones@...aro.org>,
        Guru Das Srinagesh <gurus@...eaurora.org>,
        Linux PWM List <linux-pwm@...r.kernel.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] video: ssd1307fb: Print PWM period using 64-bit
 format specifier

Hi Thierry,

On Mon, Jun 15, 2020 at 4:17 PM Thierry Reding <thierry.reding@...il.com> wrote:
> The PWM core will soon change the duty cycle and period of PWMs to 64
> bits to allow for a broader range of values. Use a 64-bit format
> specifier to avoid a warning when that change is made.
>
> Signed-off-by: Thierry Reding <thierry.reding@...il.com>

> --- a/drivers/video/fbdev/ssd1307fb.c
> +++ b/drivers/video/fbdev/ssd1307fb.c
> @@ -312,7 +312,7 @@ static int ssd1307fb_init(struct ssd1307fb_par *par)
>                 /* Enable the PWM */
>                 pwm_enable(par->pwm);
>
> -               dev_dbg(&par->client->dev, "Using PWM%d with a %dns period.\n",
> +               dev_dbg(&par->client->dev, "Using PWM%d with a %lluns period.\n",
>                         par->pwm->pwm, pwm_get_period(par->pwm));
>         }

This change must be done together with changing the return type of
pwm_get_period(), else you will get a compiler warning, and will print a
bogus value.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds