linux-kernel - [PATCH v8 6/6] r8169: Disable ASPM while doing NAPI poll

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Date:   Tue, 21 Feb 2023 10:32:37 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     hkallweit1@...il.com, nic_swsd@...ltek.com, bhelgaas@...gle.com
Cc:     koba.ko@...onical.com, acelan.kao@...onical.com,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v8 6/6] r8169: Disable ASPM while doing NAPI poll

NAPI poll of Realtek NICs don't seem to perform well ASPM is enabled.
The vendor driver uses a mechanism called "dynamic ASPM" to toggle ASPM
based on the packet number in given time period.

Instead of implementing "dynamic ASPM", use a more straightforward way
by disabling ASPM during NAPI poll, as a similar approach was
implemented to solve slow performance on Realtek wireless NIC, see
commit 24f5e38a13b5 ("rtw88: Disable PCIe ASPM while doing NAPI poll on
8821CE").

Since NAPI poll should be handled as fast as possible, also remove the
delay in rtl_hw_aspm_clkreq_enable() which was added by commit
94235460f9ea ("r8169: Align ASPM/CLKREQ setting function with vendor
driver").

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
v8:
 - New patch.

 drivers/net/ethernet/realtek/r8169_main.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 897f90b48bba6..4d4a802346ae3 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -2711,8 +2711,6 @@ static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
 		RTL_W8(tp, Config2, RTL_R8(tp, Config2) & ~ClkReqEn);
 		RTL_W8(tp, Config5, RTL_R8(tp, Config5) & ~ASPM_en);
 	}
-
-	udelay(10);
 }
 
 static void rtl_set_fifo_size(struct rtl8169_private *tp, u16 rx_stat,
@@ -4577,6 +4575,12 @@ static int rtl8169_poll(struct napi_struct *napi, int budget)
 	struct net_device *dev = tp->dev;
 	int work_done;
 
+	if (tp->aspm_manageable) {
+		rtl_unlock_config_regs(tp);
+		rtl_hw_aspm_clkreq_enable(tp, false);
+		rtl_lock_config_regs(tp);
+	}
+
 	rtl_tx(dev, tp, budget);
 
 	work_done = rtl_rx(dev, tp, budget);
@@ -4584,6 +4588,12 @@ static int rtl8169_poll(struct napi_struct *napi, int budget)
 	if (work_done < budget && napi_complete_done(napi, work_done))
 		rtl_irq_enable(tp);
 
+	if (tp->aspm_manageable) {
+		rtl_unlock_config_regs(tp);
+		rtl_hw_aspm_clkreq_enable(tp, true);
+		rtl_lock_config_regs(tp);
+	}
+
 	return work_done;
 }
 
-- 
2.34.1