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

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Date:   Thu, 15 Apr 2021 16:02:34 -0700
From:   Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
To:     Felix Fietkau <nbd@....name>, John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>,
        Mark Lee <Mark-MC.Lee@...iatek.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
Subject: [PATCH net-next] net: ethernet: mediatek: ppe: fix busy wait loop

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@...il.com>
Cc: Felix Fietkau <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;
 
-- 
2.31.1