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    SubjectRe: [PATCH v2] pwm: bcm2835: Support apply function for atomic configuration
    Hello Lino,

    On Fri, Dec 04, 2020 at 12:42:15AM +0100, Lino Sanfilippo wrote:
    > On 29.11.20 at 19:10, Uwe Kleine-König wrote:
    > > You're storing an unsigned long long (i.e. 64 bits) in an u32. If
    > > you are sure that this won't discard relevant bits, please explain
    > > this in a comment for the cursory reader.
    >
    > What about an extra check then to make sure that the period has not been truncated,
    > e.g:
    >
    > value = DIV_ROUND_CLOSEST_ULL(state->period, scaler);
    >
    > /* dont accept a period that is too small or has been truncated */
    > if ((value < PERIOD_MIN) ||
    > (value != DIV_ROUND_CLOSEST_ULL(state->period, scaler)))
    > return -EINVAL;

    I'd make value an unsigned long long and check for > 0xffffffff instead
    of repeating the (expensive) division. (Hmm, maybe the compiler is smart
    enough to not actually repeat it, but still.)

    Best regards
    Uwe

    --
    Pengutronix e.K. | Uwe Kleine-König |
    Industrial Linux Solutions | https://www.pengutronix.de/ |
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