[PATCH 1/4] rtc: zynqmp: correct frequency value

[T, Harini]

[Public]

Hi,

> -----Original Message-----
> From: Tomas Melin <tomas.melin at vaisala.com>
> Sent: Monday, December 1, 2025 6:20 PM
> To: Alexandre Belloni <alexandre.belloni at bootlin.com>; Simek, Michal
> <michal.simek at amd.com>
> Cc: linux-rtc at vger.kernel.org; linux-arm-kernel at lists.infradead.org; linux-
> kernel at vger.kernel.org; Tomas Melin <tomas.melin at vaisala.com>
> Subject: [PATCH 1/4] rtc: zynqmp: correct frequency value
>
> Caution: This message originated from an External Source. Use proper
> caution when opening attachments, clicking links, or responding.
>
>
> Fix calibration value in case a clock reference is provided.
> The actual calibration value written into register is
> frequency - 1.
>
> Signed-off-by: Tomas Melin <tomas.melin at vaisala.com>
> ---
>  drivers/rtc/rtc-zynqmp.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
> index
> 3baa2b481d9f2008750046005283b98a0d546c5c..856bc1678e7d31144f320ae
> 9f75fc58c742a2a64 100644
> --- a/drivers/rtc/rtc-zynqmp.c
> +++ b/drivers/rtc/rtc-zynqmp.c
> @@ -345,7 +345,10 @@ static int xlnx_rtc_probe(struct platform_device
> *pdev)
>                                            &xrtcdev->freq);
>                 if (ret)
>                         xrtcdev->freq = RTC_CALIB_DEF;
> +       } else {
> +               xrtcdev->freq--;
If freq > 65536, the 16-bit register silently truncates.
Please add some checks for above mentioned scenario.
>         }
> +
>         ret = readl(xrtcdev->reg_base + RTC_CALIB_RD);
>         if (!ret)
>                 writel(xrtcdev->freq, (xrtcdev->reg_base + RTC_CALIB_WR));
>
> --
> 2.47.3
>
Thanks,
Harini T