Re: [PATCH v8 RESEND 6/6] r8169: Disable ASPM while doing NAPI poll

On Tue, Feb 21, 2023 at 7:09 PM Heiner Kallweit [off-list ref] wrote:

On 21.02.2023 03:38, Kai-Heng Feng wrote:

quoted

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 <redacted>
---
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);

NAPI poll runs in softirq context (except for threaded NAPI).
Therefore you should use a spinlock instead of a mutex.

You are right. Will change it in next revision.

quoted

+             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);

Why not moving lock/unlock into rtl_hw_aspm_clkreq_enable()?

Because where it gets called at other places don't need the lock.
But yes this will make it easier to read, will do in next revision.

Kai-Heng

quoted

+     }
+
      return work_done;
 }