[PATCH net-next] net: stmmac: Convert open-coded register polling to helper macro

[PATCH net-next] net: stmmac: Convert open-coded register polling to helper macro

[Furong Xu]

Drop the open-coded register polling routines.
Use readl_poll_timeout_atomic() in atomic state.

Compile tested only.
No functional change intended.

Signed-off-by: Furong Xu <0x1207@gmail.com>
---
 .../ethernet/stmicro/stmmac/stmmac_hwtstamp.c | 28 ++++---------------
 1 file changed, 6 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
index e2840fa241f2..9e445ad1aa77 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
@@ -135,7 +135,6 @@ static int init_systime(void __iomem *ioaddr, u32 sec, u32 nsec)
 static int config_addend(void __iomem *ioaddr, u32 addend)
 {
 	u32 value;
-	int limit;
 
 	writel(addend, ioaddr + PTP_TAR);
 	/* issue command to update the addend value */
@@ -144,23 +143,15 @@ static int config_addend(void __iomem *ioaddr, u32 addend)
 	writel(value, ioaddr + PTP_TCR);
 
 	/* wait for present addend update to complete */
-	limit = 10;
-	while (limit--) {
-		if (!(readl(ioaddr + PTP_TCR) & PTP_TCR_TSADDREG))
-			break;
-		mdelay(10);
-	}
-	if (limit < 0)
-		return -EBUSY;
-
-	return 0;
+	return readl_poll_timeout_atomic(ioaddr + PTP_TCR, value,
+				!(value & PTP_TCR_TSADDREG),
+				10, 100000);
 }
 
 static int adjust_systime(void __iomem *ioaddr, u32 sec, u32 nsec,
 		int add_sub, int gmac4)
 {
 	u32 value;
-	int limit;
 
 	if (add_sub) {
 		/* If the new sec value needs to be subtracted with
@@ -187,16 +178,9 @@ static int adjust_systime(void __iomem *ioaddr, u32 sec, u32 nsec,
 	writel(value, ioaddr + PTP_TCR);
 
 	/* wait for present system time adjust/update to complete */
-	limit = 10;
-	while (limit--) {
-		if (!(readl(ioaddr + PTP_TCR) & PTP_TCR_TSUPDT))
-			break;
-		mdelay(10);
-	}
-	if (limit < 0)
-		return -EBUSY;
-
-	return 0;
+	return readl_poll_timeout_atomic(ioaddr + PTP_TCR, value,
+				!(value & PTP_TCR_TSUPDT),
+				10, 100000);
 }
 
 static void get_systime(void __iomem *ioaddr, u64 *systime)
-- 
2.43.0

Re: [PATCH net-next] net: stmmac: Convert open-coded register polling to helper macro

[Simon Horman]

On Wed, Sep 24, 2025 at 11:22:17PM +0800, Furong Xu wrote:
> Drop the open-coded register polling routines.
> Use readl_poll_timeout_atomic() in atomic state.
> 
> Compile tested only.
> No functional change intended.
> 
> Signed-off-by: Furong Xu <0x1207@gmail.com>

I agree this is correct. Or at least, it looks correct to me.
But, FWIIW, I do have some hesitation about untested code of this nature
being accepted so close to the merge window.

Reviewed-by: Simon Horman <horms@kernel.org>

...

Re: [PATCH net-next] net: stmmac: Convert open-coded register polling to helper macro

[Jakub Kicinski]

On Wed, 24 Sep 2025 23:22:17 +0800 Furong Xu wrote:
>  	writel(addend, ioaddr + PTP_TAR);
>  	/* issue command to update the addend value */
> @@ -144,23 +143,15 @@ static int config_addend(void __iomem *ioaddr, u32 addend)
>  	writel(value, ioaddr + PTP_TCR);
>  
>  	/* wait for present addend update to complete */
> -	limit = 10;
> -	while (limit--) {
> -		if (!(readl(ioaddr + PTP_TCR) & PTP_TCR_TSADDREG))
> -			break;
> -		mdelay(10);
> -	}
> -	if (limit < 0)
> -		return -EBUSY;
> -
> -	return 0;
> +	return readl_poll_timeout_atomic(ioaddr + PTP_TCR, value,
> +				!(value & PTP_TCR_TSADDREG),

Why the strange alignment ? I think you can start the continuation line
under the opening bracket and still easily fit in 80 chars?

> +				10, 100000);

You say in the commit message "no functional changes intended"
but you changed the frequency of polling from 10msec to 10usec.
Seems like a reasonable change, but the commit message is lying.
-- 
pw-bot: cr