Messages in this thread | | | From | Arnd Bergmann <> | Date | Tue, 31 Mar 2020 17:24:52 +0200 | Subject | Re: [PATCH v11 06/12] pwm: imx27: Use 64-bit division macro and function |
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On Mon, Mar 30, 2020 at 10:44 PM Guru Das Srinagesh <gurus@codeaurora.org> wrote: > > On Fri, Mar 20, 2020 at 06:09:39PM +0100, Arnd Bergmann wrote: > > On Fri, Mar 20, 2020 at 2:42 AM Guru Das Srinagesh <gurus@codeaurora.org> wrote: > > > > > @@ -240,8 +240,7 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm, > > > > > > period_cycles /= prescale; > > > c = (unsigned long long)period_cycles * state->duty_cycle; > > > - do_div(c, state->period); > > > - duty_cycles = c; > > > + duty_cycles = div64_u64(c, state->period); > > > > > > > This change looks fine, but I wonder if the code directly above it > > > > c = clk_get_rate(imx->clk_per); > > c *= state->period; > > do_div(c, 1000000000); > > period_cycles = c; > > > > might run into an overflow when both the clock rate and the period > > are large numbers. > > Hmm. Seems to me like addressing this would be outside the scope of this > patch series.
I think it should be part of the same series, addressing bugs that were introduced by the change to 64-bit period. If it's not getting fixed along with the other regressions, I fear nobody is going to go back and fix it later.
Arnd
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