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    SubjectRe: [PATCH v6] pwm: atmel: Enable clk when pwm already enabled in bootloader
    On Thu, Jul 20, 2023 at 05:12:30PM +0200, Thierry Reding wrote:
    > On Sun, Jul 16, 2023 at 10:06:52AM +0800, Guiting Shen wrote:
    > > +static int atmel_pwm_enable_clk_if_on(struct atmel_pwm_chip *atmel_pwm, bool on)
    > > +{
    > > + unsigned int i, cnt = 0;
    > > + int ret = 0;
    > > + u32 sr;
    > > +
    > > + sr = atmel_pwm_readl(atmel_pwm, PWM_SR) & PWM_SR_ALL_CH_MASK;
    > > + if (!sr)
    > > + return 0;
    > > +
    > > + cnt = bitmap_weight((unsigned long *)&sr, atmel_pwm->chip.npwm);
    >
    > Tiny nit here: not sure if that cast is safe to do. You've got a 32-bit
    > variable, but if you cast &sr to unsigned long * on a 64-bit machine it
    > would cause hweight64() to get called and that would then read 64 bits
    > from a 32-bit variable. This probably works most of the time because we
    > don't read any of the upper bits, but it is strictly an illegal access
    > and could be unaligned as well.

    While relevance of BE systems ceases slowly, such a machine would
    evaluate the wrong bits.

    > Should we just turn sr into an unsigned long to be safe here?

    yes please.

    Best regards
    Uwe

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