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[net-next] net: ethernet: mediatek: ppe: fix busy wait loop

Message ID 20210415230234.14895-1-ilya.lipnitskiy@gmail.com (mailing list archive)
State New
Headers show
Series [net-next] net: ethernet: mediatek: ppe: fix busy wait loop | expand

Commit Message

Ilya Lipnitskiy April 15, 2021, 11:02 p.m. UTC
The intention is for the loop to timeout if the body does not succeed.
The current logic calls time_is_before_jiffies(timeout) which is false
until after the timeout, so the loop body never executes.

time_is_after_jiffies(timeout) will return true until timeout is less
than jiffies, which is the intended behavior here.

Fixes: ba37b7caf1ed ("net: ethernet: mtk_eth_soc: add support for initializing the PPE")
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Cc: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/ethernet/mediatek/mtk_ppe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Andrew Lunn April 15, 2021, 11:10 p.m. UTC | #1
On Thu, Apr 15, 2021 at 04:02:34PM -0700, Ilya Lipnitskiy wrote:
> The intention is for the loop to timeout if the body does not succeed.
> The current logic calls time_is_before_jiffies(timeout) which is false
> until after the timeout, so the loop body never executes.
> 
> time_is_after_jiffies(timeout) will return true until timeout is less
> than jiffies, which is the intended behavior here.
> 
> Fixes: ba37b7caf1ed ("net: ethernet: mtk_eth_soc: add support for initializing the PPE")
> Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
> Cc: Felix Fietkau <nbd@nbd.name>
> ---
>  drivers/net/ethernet/mediatek/mtk_ppe.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_ppe.c b/drivers/net/ethernet/mediatek/mtk_ppe.c
> index 71e1ccea6e72..af3c266297aa 100644
> --- a/drivers/net/ethernet/mediatek/mtk_ppe.c
> +++ b/drivers/net/ethernet/mediatek/mtk_ppe.c
> @@ -46,7 +46,7 @@ static int mtk_ppe_wait_busy(struct mtk_ppe *ppe)
>  {
>  	unsigned long timeout = jiffies + HZ;
>  
> -	while (time_is_before_jiffies(timeout)) {
> +	while (time_is_after_jiffies(timeout)) {
>  		if (!(ppe_r32(ppe, MTK_PPE_GLO_CFG) & MTK_PPE_GLO_CFG_BUSY))
>  			return 0;

Maybe see is iopoll.h can be used.

      Andrew

>  
> -- 
> 2.31.1
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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Patch

diff --git a/drivers/net/ethernet/mediatek/mtk_ppe.c b/drivers/net/ethernet/mediatek/mtk_ppe.c
index 71e1ccea6e72..af3c266297aa 100644
--- a/drivers/net/ethernet/mediatek/mtk_ppe.c
+++ b/drivers/net/ethernet/mediatek/mtk_ppe.c
@@ -46,7 +46,7 @@  static int mtk_ppe_wait_busy(struct mtk_ppe *ppe)
 {
 	unsigned long timeout = jiffies + HZ;
 
-	while (time_is_before_jiffies(timeout)) {
+	while (time_is_after_jiffies(timeout)) {
 		if (!(ppe_r32(ppe, MTK_PPE_GLO_CFG) & MTK_PPE_GLO_CFG_BUSY))
 			return 0;