linux-kernel - Re: [PATCH V2 2/2] backlight: qcom-wled: Correct the sync

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Message-ID: <20210301093902.34mtfcouajc36y6t@maple.lan>
Date:   Mon, 1 Mar 2021 09:39:02 +0000
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     kgunda@...eaurora.org
Cc:     bjorn.andersson@...aro.org, jingoohan1@...il.com,
        lee.jones@...aro.org, b.zolnierkie@...sung.com,
        dri-devel@...ts.freedesktop.org, jacek.anaszewski@...il.com,
        pavel@....cz, robh+dt@...nel.org, mark.rutland@....com,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Andy Gross <agross@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-fbdev@...r.kernel.org,
        phone-devel@...r.kernel.org
Subject: Re: [PATCH V2 2/2] backlight: qcom-wled: Correct the sync_toggle
 sequence

On Mon, Mar 01, 2021 at 02:15:12PM +0530, kgunda@...eaurora.org wrote:
> On 2021-02-26 22:56, Daniel Thompson wrote:
> > On Fri, Feb 26, 2021 at 05:42:24PM +0530, Kiran Gunda wrote:
> > > As per the current implementation, after FSC (Full Scale Current)
> > > and brightness update the sync bits are transitioned from 1 to 0.
> > 
> > This still seems to incorrectly describe the current behaviour.
> > 
> > Surely in most cases (i.e. every time except the first) the value of the
> > sync bit is 0 when the function is called and we get both a 0 to 1
> > and then a 1 to 0 transition.
> > 
> > That is why I recommended set-then-clear terminology to describe the
> > current behaviour. It is concise and correct.
>
> Okay. Actually I have mentioned the "clear-and-set" in explaining the fix.
> Let me modify the same terminology in explaining the problem case also.

Yes please.

In my original review I took time to explain why patch descriptions
require care and attention and, also, why expressing the original behaviour
as 1 to 0 was inadequate. Based on the previous feedback (and reply) I
was rather surprised that the problem was only half corrected in the
next revision.


Daniel.