linux-kernel - Re: [PATCH v2] leds: qcom-lpg: Fix PWM period limits

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Message-ID: <20230602091928.GR449117@google.com>
Date:   Fri, 2 Jun 2023 10:19:28 +0100
From:   Lee Jones <lee@...nel.org>
To:     Johan Hovold <johan@...nel.org>
Cc:     Bjorn Andersson <quic_bjorande@...cinc.com>,
        Pavel Machek <pavel@....cz>,
        Anjelique Melendez <quic_amelende@...cinc.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Caleb Connolly <caleb.connolly@...aro.org>,
        Steev Klimaszewski <steev@...i.org>
Subject: Re: [PATCH v2] leds: qcom-lpg: Fix PWM period limits

On Wed, 24 May 2023, Johan Hovold wrote:

> On Mon, May 15, 2023 at 09:26:04AM -0700, Bjorn Andersson wrote:
> > The introduction of high resolution PWM support changed the order of the
> > operations in the calculation of min and max period. The result in both
> > divisions is in most cases a truncation to 0, which limits the period to
> > the range of [0, 0].
> > 
> > Both numerators (and denominators) are within 64 bits, so the whole
> > expression can be put directly into the div64_u64, instead of doing it
> > partially.
> > 
> > Fixes: b00d2ed37617 ("leds: rgb: leds-qcom-lpg: Add support for high resolution PWM")
> > Reviewed-by: Caleb Connolly <caleb.connolly@...aro.org>
> > Tested-by: Steev Klimaszewski <steev@...i.org>
> > Signed-off-by: Bjorn Andersson <quic_bjorande@...cinc.com>
> 
> Tested-by: Johan Hovold <johan+linaro@...nel.org>
> 
> Pavel or Lee, could you pick this one up for 6.4 as it fixes a
> regression (e.g. broken backlight on a number of laptops like the X13s)?

I don't presently have any plans for a -fixes submission.

If anyone else would like to submit it, please be my guest:

Acked-by: Lee Jones <lee@...nel.org>

-- 
Lee Jones [李琼斯]