[PATCH v12 09/11] backlight: pwm_bl: Use 64-bit division function

[PATCH v12 09/11] backlight: pwm_bl: Use 64-bit division function

[Guru Das Srinagesh]

Since the PWM framework is switching struct pwm_state.period's datatype
to u64, prepare for this transition by using div_u64 to handle a 64-bit
dividend instead of a straight division operation.

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: linux-pwm@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org

Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---
 drivers/video/backlight/pwm_bl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index efb4efc..3e5dbcf 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -625,7 +625,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		pb->scale = data->max_brightness;
 	}
 
-	pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
+	pb->lth_brightness = data->lth_brightness * (div_u64(state.period,
+				pb->scale));
 
 	props.type = BACKLIGHT_RAW;
 	props.max_brightness = data->max_brightness;
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v12 09/11] backlight: pwm_bl: Use 64-bit division function

[Lee Jones]

On Wed, 08 Apr 2020, Guru Das Srinagesh wrote:

> Since the PWM framework is switching struct pwm_state.period's datatype
> to u64, prepare for this transition by using div_u64 to handle a 64-bit
> dividend instead of a straight division operation.
> 
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Jingoo Han <jingoohan1@gmail.com>
> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> Cc: linux-pwm@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-fbdev@vger.kernel.org
> 
> Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> ---
>  drivers/video/backlight/pwm_bl.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

I see that this is part of a large set, but the remainder of the
patches have been hidden from me.

Does this mean I can apply this patch on its own?

> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index efb4efc..3e5dbcf 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -625,7 +625,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
>  		pb->scale = data->max_brightness;
>  	}
>  
> -	pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
> +	pb->lth_brightness = data->lth_brightness * (div_u64(state.period,
> +				pb->scale));
>  
>  	props.type = BACKLIGHT_RAW;
>  	props.max_brightness = data->max_brightness;

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH v12 09/11] backlight: pwm_bl: Use 64-bit division function

[Guru Das Srinagesh]

On Thu, Apr 16, 2020 at 10:44:20AM +0100, Lee Jones wrote:
> On Wed, 08 Apr 2020, Guru Das Srinagesh wrote:
> 
> > Since the PWM framework is switching struct pwm_state.period's datatype
> > to u64, prepare for this transition by using div_u64 to handle a 64-bit
> > dividend instead of a straight division operation.
> > 
> > Cc: Lee Jones <lee.jones@linaro.org>
> > Cc: Daniel Thompson <daniel.thompson@linaro.org>
> > Cc: Jingoo Han <jingoohan1@gmail.com>
> > Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> > Cc: linux-pwm@vger.kernel.org
> > Cc: dri-devel@lists.freedesktop.org
> > Cc: linux-fbdev@vger.kernel.org
> > 
> > Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>
> > Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> > ---
> >  drivers/video/backlight/pwm_bl.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> I see that this is part of a large set, but the remainder of the
> patches have been hidden from me.

Sorry about that, the full series is here: [1].

> Does this mean I can apply this patch on its own?

I'll defer to Uwe on this point as I am not sure of the implications of
taking in this single patch and not the entire series.

Thank you.

Guru Das.

[1] https://www.spinics.net/lists/linux-pwm/msg12131.html