[PATCH v1] rtc: mpfs: fix counter upload completion condition

[Conor Dooley]

Hey Alexandrew,

On Wed, May 13, 2026 at 06:55:55PM +0100, Conor Dooley wrote:
> From: Conor Dooley <conor.dooley at microchip.com>
> 
> The condition that needs to be checked for upload completion is the
> UPLOAD bit in the completion register going low. The original iterations
> of this driver used a do-while and this was converted to a
> read_poll_timeout() during upstreaming without the condition being
> inverted as it should have been.
> 
> I suspect that this went unnoticed until now because a) the first read
> was done when the bit was still set, immediately completing the
> read_poll_timeout() and b) because the RTC doesn't hold time when power
> is removed from the SoC reducing its utility (I for one keep it
> disabled). If my first suspicion was true when the driver was
> upstreamed, it's not true any longer though, hence the detection of the
> problem.
> 
> Fixes: 0b31d703598dc ("rtc: Add driver for Microchip PolarFire SoC")
> CC: stable at vger.kernel.org
> Signed-off-by: Conor Dooley <conor.dooley at microchip.com>

Any chance this could be applied as 7.1 fixes material?

Apologies if I missed an application mail somewhere,
Conor.

> ---
> CC: Valentina.FernandezAlanis at microchip.com
> CC: Conor Dooley <conor.dooley at microchip.com>
> CC: Daire McNamara <daire.mcnamara at microchip.com>
> CC: Alexandre Belloni <alexandre.belloni at bootlin.com>
> CC: linux-riscv at lists.infradead.org
> CC: linux-rtc at vger.kernel.org
> CC: linux-kernel at vger.kernel.org
> ---
>  drivers/rtc/rtc-mpfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/rtc/rtc-mpfs.c b/drivers/rtc/rtc-mpfs.c
> index 6aa3eae575d2a..ece6de4a6adbd 100644
> --- a/drivers/rtc/rtc-mpfs.c
> +++ b/drivers/rtc/rtc-mpfs.c
> @@ -112,7 +112,7 @@ static int mpfs_rtc_settime(struct device *dev, struct rtc_time *tm)
>  	ctrl |= CONTROL_UPLOAD_BIT;
>  	writel(ctrl, rtcdev->base + CONTROL_REG);
>  
> -	ret = read_poll_timeout(readl, prog, prog & CONTROL_UPLOAD_BIT, 0, UPLOAD_TIMEOUT_US,
> +	ret = read_poll_timeout(readl, prog, !(prog & CONTROL_UPLOAD_BIT), 0, UPLOAD_TIMEOUT_US,
>  				false, rtcdev->base + CONTROL_REG);
>  	if (ret) {
>  		dev_err(dev, "timed out uploading time to rtc");
> -- 
> 2.53.0
> 
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