netdev - [PATCH] Re: still having r8169 woes with XID 18000000

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Message-ID: <4C09FF4B.4050601@iki.fi>
Date:	Sat, 05 Jun 2010 10:39:55 +0300
From:	Timo Teräs <timo.teras@....fi>
To:	Phil Sutter <phil@....cc>,
	françois romieu <romieu@...zoreil.com>,
	netdev@...r.kernel.org
Subject: [PATCH] Re: still having r8169 woes with XID 18000000

On 06/04/2010 11:24 PM, Timo Teräs wrote:
> On 06/04/2010 08:31 PM, Timo Teräs wrote:
> r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded
> r8169 0000:00:09.0: PCI->APIC IRQ transform: INT A -> IRQ 18
> r8169 0000:00:09.0: no PCI Express capability
> eth0: RTL8169sc/8110sc at 0xf835c000, 00:30:18:a6:2b:6c, XID 18000000 IRQ 18
> r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded
> r8169 0000:00:0b.0: PCI->APIC IRQ transform: INT A -> IRQ 19
> r8169 0000:00:0b.0: no PCI Express capability
> eth1: RTL8169sc/8110sc at 0xf8360000, 00:30:18:a6:2b:6d, XID 18000000 IRQ 19
> r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded
> r8169 0000:00:0c.0: PCI->APIC IRQ transform: INT A -> IRQ 16
> r8169 0000:00:0c.0: no PCI Express capability
> eth2: RTL8169sc/8110sc at 0xf8364000, 00:30:18:a6:2b:6e, XID 18000000 IRQ 16
> r8169: mdio_write(f8364000, 0x00000003, 0000000a1) required 2000 cycles
> r8169: mdio_write(f8364000, 0x00000000, 000001000) required 2000 cycles
> r8169: mdio_write(f8364000, 0x00000000, 00000a0ff) required 2000 cycles
> r8169: mdio_write(f8364000, 0x00000014, 00000fb54) required 2000 cycles
> 
> And eth2 was not working. Reloading the module gave a lot of other
> mdio_write and mdio_read errors.
> 
> It seems to be pretty random when the errors occur, but that's the
> reason why the NIC stops working: mdio_write() fails (one or more times)
> at some crucial point of the board specific phy config code resulting in
> bad state.
> 
> Any ideas how to debug this further?

Ok, I compared Realtek's and the in-tree driver. The only essential
difference is that Realtek driver uses udelay(100) in mdio_write()'s
busy polling loop where as the in-tree uses udelay(25). And that seems
to be the magic difference! Using udelay(100) fixes this!

I'm guessing that the phy needs slight delay between consecutive
mdio_write's even if it has advertised that the write has been
completed. And yes, just adding a small delay in the end of mdio_write
does seem to work too.

Francois, you think the below patch is ok? Should I send it as properly
formatted commit?

diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
index 217e709..6db62bf 100644
--- a/drivers/net/r8169.c
+++ b/drivers/net/r8169.c
@@ -559,6 +559,7 @@ static void mdio_write(void __iomem *ioaddr,
 			break;
 		udelay(25);
 	}
+	udelay(25);
 }

 static int mdio_read(void __iomem *ioaddr, int reg_addr)
--
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