linux-kernel - Re: [PATCH v3 01/13] clk: mmp: frac: Do not lose last 4 digits of precision

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Message-ID: <159062766126.69627.12547507696491958467@swboyd.mtv.corp.google.com>
Date:   Wed, 27 May 2020 18:01:01 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Lubomir Rintel <lkundrak@...sk>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Lubomir Rintel <lkundrak@...sk>
Subject: Re: [PATCH v3 01/13] clk: mmp: frac: Do not lose last 4 digits of precision

Quoting Lubomir Rintel (2020-05-19 15:41:39)
> While calculating the output rate of a fractional divider clock, the
> value is divided and multipled by 10000, discarding the least
> significant digits -- presumably to fit the intermediate value within 32
> bits.
> 
> The precision we're losing is, however, not insignificant for things like
> I2S clock. Maybe also elsewhere, now that since commit ea56ad60260e ("clk:
> mmp2: Stop pretending PLL outputs are constant") the parent rates are more
> precise and no longer rounded to 10000s.
> 
> Signed-off-by: Lubomir Rintel <lkundrak@...sk>
> ---

Applied to clk-next