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Date: Fri, 2 Aug 2013 21:18:55 +0200
From: Ben Hutchings <bhutchings@...arflare.com>
To: Denis Kirjanov <kda@...ux-powerpc.org>
CC: <davem@...emloft.net>, <venza@...wnhat.org>,
<B38611@...escale.com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH v3] sis900: Fix the tx queue timeout issue
On Fri, 2013-08-02 at 13:50 +0400, Denis Kirjanov wrote:
> [ 198.720048] ------------[ cut here ]------------
> [ 198.720108] WARNING: CPU: 0 PID: 0 at net/sched/sch_generic.c:255 dev_watchdog+0x229/0x240()
> [ 198.720118] NETDEV WATCHDOG: eth0 (sis900): transmit queue 0 timed out
> [ 198.720125] Modules linked in: bridge stp llc dmfe sundance 3c59x sis900 mii
> [ 198.720159] CPU: 0 PID: 0 Comm: swapper Not tainted 3.11.0-rc3+ #12
> [ 198.720167] Hardware name: System Manufacturer System Name/TUSI-M, BIOS ASUS TUSI-M ACPI BIOS
> Revision 1013 Beta 001 12/14/2001
> [ 198.720175] 000000ff c13fa6b9 c169ddcc c12208d6 c169ddf8 c1031e4d c1664a84 c169de24
> [ 198.720197] 00000000 c165f5ea 000000ff c13fa6b9 00000001 000000ff c1664a84 c169de10
> [ 198.720217] c1031f13 00000009 c169de08 c1664a84 c169de24 c169de50 c13fa6b9 c165f5ea
> [ 198.720240] Call Trace:
> [ 198.720257] [<c13fa6b9>] ? dev_watchdog+0x229/0x240
> [ 198.720274] [<c12208d6>] dump_stack+0x16/0x20
> [ 198.720306] [<c1031e4d>] warn_slowpath_common+0x7d/0xa0
> [ 198.720318] [<c13fa6b9>] ? dev_watchdog+0x229/0x240
> [ 198.720330] [<c1031f13>] warn_slowpath_fmt+0x33/0x40
> [ 198.720342] [<c13fa6b9>] dev_watchdog+0x229/0x240
> [ 198.720357] [<c103f158>] call_timer_fn+0x78/0x150
> [ 198.720369] [<c103f0e0>] ? internal_add_timer+0x40/0x40
> [ 198.720381] [<c13fa490>] ? dev_init_scheduler+0xa0/0xa0
> [ 198.720392] [<c103f33f>] run_timer_softirq+0x10f/0x200
> [ 198.720412] [<c103954f>] ? __do_softirq+0x6f/0x210
> [ 198.720424] [<c13fa490>] ? dev_init_scheduler+0xa0/0xa0
> [ 198.720435] [<c1039598>] __do_softirq+0xb8/0x210
> [ 198.720467] [<c14b54d2>] ? _raw_spin_unlock+0x22/0x30
> [ 198.720484] [<c1003245>] ? handle_irq+0x25/0xd0
> [ 198.720496] [<c1039c0c>] irq_exit+0x9c/0xb0
> [ 198.720508] [<c14bc9d7>] do_IRQ+0x47/0x94
> [ 198.720534] [<c1056078>] ? hrtimer_start+0x28/0x30
> [ 198.720564] [<c14bc8b1>] common_interrupt+0x31/0x38
> [ 198.720589] [<c1008692>] ? default_idle+0x22/0xa0
> [ 198.720600] [<c10083c7>] arch_cpu_idle+0x17/0x30
> [ 198.720631] [<c106d23d>] cpu_startup_entry+0xcd/0x180
> [ 198.720643] [<c14ae30a>] rest_init+0xaa/0xb0
> [ 198.720654] [<c14ae260>] ? reciprocal_value+0x50/0x50
> [ 198.720668] [<c17044e0>] ? repair_env_string+0x60/0x60
> [ 198.720679] [<c1704bda>] start_kernel+0x29a/0x350
> [ 198.720690] [<c17044e0>] ? repair_env_string+0x60/0x60
> [ 198.720721] [<c1704269>] i386_start_kernel+0x39/0xa0
> [ 198.720729] ---[ end trace 81e0a6266f5c73a8 ]---
> [ 198.720740] eth0: Transmit timeout, status 00000204 00000000
>
> timer routine checks the link status and if it's up calls
> netif_carrier_on() allowing upper layer to start the tx queue
> even if the auto-negotiation process is not finished.
>
> Also remove ugly auto-negotiation check from the sis900_start_xmit()
>
> CC: Duan Fugang <B38611@...escale.com>
> CC: Ben Hutchings <bhutchings@...arflare.com>
>
> Signed-off-by: Denis Kirjanov <kda@...ux-powerpc.org>
> ---
> v1->v2: use netdev_dbg() instead of printk()
> v2->v3:
> handle link change from timer,
> remove auto-negotiation check from xmit path
This looks reasonable. It looks like link changes now work like this:
1. When sis900_timer() detects link-down, it calls netif_carrier_off()
but does not clear autong_complete.
2. When sis900_timer() detects link-up, it calls sis900_check_mode()
which restarts autonegotiation and clears autong_complete.
3. sis900_timer() will now call sis900_read_mode(). When that detects
link-up, it sets autong_complete and calls netif_carrier_on().
This patch has moved the call to netif_carrier_on() from step 2 to step
3. However, I don't understand why autonegotiation is restarted in step
2. When autonegotiation is enabled, the PHY should not indicate link-up
until it has completed. Perhaps this is a necessary workaround for a
hardware bug. Otherwise it's a waste of time.
Ben.
> ---
> drivers/net/ethernet/sis/sis900.c | 12 ++----------
> 1 file changed, 2 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/ethernet/sis/sis900.c b/drivers/net/ethernet/sis/sis900.c
> index eb4aea3..f5d7ad7 100644
> --- a/drivers/net/ethernet/sis/sis900.c
> +++ b/drivers/net/ethernet/sis/sis900.c
> @@ -1318,7 +1318,7 @@ static void sis900_timer(unsigned long data)
> if (duplex){
> sis900_set_mode(sis_priv, speed, duplex);
> sis630_set_eq(net_dev, sis_priv->chipset_rev);
> - netif_start_queue(net_dev);
> + netif_carrier_on(net_dev);
> }
>
> sis_priv->timer.expires = jiffies + HZ;
> @@ -1336,10 +1336,8 @@ static void sis900_timer(unsigned long data)
> status = sis900_default_phy(net_dev);
> mii_phy = sis_priv->mii;
>
> - if (status & MII_STAT_LINK){
> + if (status & MII_STAT_LINK)
> sis900_check_mode(net_dev, mii_phy);
> - netif_carrier_on(net_dev);
> - }
> } else {
> /* Link ON -> OFF */
> if (!(status & MII_STAT_LINK)){
> @@ -1612,12 +1610,6 @@ sis900_start_xmit(struct sk_buff *skb, struct net_device *net_dev)
> unsigned int index_cur_tx, index_dirty_tx;
> unsigned int count_dirty_tx;
>
> - /* Don't transmit data before the complete of auto-negotiation */
> - if(!sis_priv->autong_complete){
> - netif_stop_queue(net_dev);
> - return NETDEV_TX_BUSY;
> - }
> -
> spin_lock_irqsave(&sis_priv->lock, flags);
>
> /* Calculate the next Tx descriptor entry. */
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
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