netdev - Re: [PATCH 1/5] NetXen: Fix softlock seen on some machines during hardware writes

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Message-Id: <200703101241.38332.amitkale@netxen.com>
Date:	Sat, 10 Mar 2007 12:41:37 +0530
From:	Amit Kale <amitkale@...xen.com>
To:	Stephen Hemminger <shemminger@...ux-foundation.org>
Cc:	Linsys Contractor Mithlesh Thukral <mithlesh@...xen.com>,
	netdev@...r.kernel.org, jeff@...zik.org, netxenproj@...syssoft.com,
	rob@...xen.com
Subject: Re: [PATCH 1/5] NetXen: Fix softlock seen on some machines during hardware writes

On Friday 09 March 2007 21:56, Stephen Hemminger wrote:
> Linsys Contractor Mithlesh Thukral wrote:
> > NetXen: This will fix a softlock seen on some machines.
> > The reason was too much time was spent waiting for writes to go through.
> >
> > Signed-off by: Mithlesh Thukral <mithlesh@...xen.com>
> > ---
> >  drivers/net/netxen/netxen_nic.h         |    1 +
> >  drivers/net/netxen/netxen_nic_ethtool.c |    1 +
> >  drivers/net/netxen/netxen_nic_init.c    |   11 +++++++++--
> >  3 files changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/netxen/netxen_nic.h
> > b/drivers/net/netxen/netxen_nic.h index 38d7409..c85c2cb 100644
> > --- a/drivers/net/netxen/netxen_nic.h
> > +++ b/drivers/net/netxen/netxen_nic.h
> > @@ -236,6 +236,7 @@ #define MPORT_MULTI_FUNCTION_MODE 0x2222
> >
> >  #include "netxen_nic_phan_reg.h"
> >  extern unsigned long long netxen_dma_mask;
> > +extern unsigned long last_schedule_time;
> >
> >  /*
> >   * NetXen host-peg signal message structure
> > diff --git a/drivers/net/netxen/netxen_nic_ethtool.c
> > b/drivers/net/netxen/netxen_nic_ethtool.c index 3752d2a..d49a7d8 100644
> > --- a/drivers/net/netxen/netxen_nic_ethtool.c
> > +++ b/drivers/net/netxen/netxen_nic_ethtool.c
> > @@ -455,6 +455,7 @@ netxen_nic_set_eeprom(struct net_device
> >  		}
> >  		printk(KERN_INFO "%s: flash unlocked. \n",
> >  			netxen_nic_driver_name);
> > +		last_schedule_time = jiffies;
> >  		ret = netxen_flash_erase_secondary(adapter);
> >  		if (ret != FLASH_SUCCESS) {
> >  			printk(KERN_ERR "%s: Flash erase failed.\n",
> > diff --git a/drivers/net/netxen/netxen_nic_init.c
> > b/drivers/net/netxen/netxen_nic_init.c index b2e776f..53ca21e 100644
> > --- a/drivers/net/netxen/netxen_nic_init.c
> > +++ b/drivers/net/netxen/netxen_nic_init.c
> > @@ -42,6 +42,8 @@ struct crb_addr_pair {
> >  	u32 data;
> >  };
> >
> > +unsigned long last_schedule_time;
> > +
> >  #define NETXEN_MAX_CRB_XFORM 60
> >  static unsigned int crb_addr_xform[NETXEN_MAX_CRB_XFORM];
> >  #define NETXEN_ADDR_ERROR (0xffffffff)
> > @@ -404,9 +406,14 @@ static inline int do_rom_fast_write(stru
> >  static inline int
> >  do_rom_fast_read(struct netxen_adapter *adapter, int addr, int *valp)
> >  {
> > +	if (jiffies > (last_schedule_time + (8 * HZ))) {
> > +		last_schedule_time = jiffies;
> > +		schedule();
> > +	}
> > +
> >  	netxen_nic_reg_write(adapter, NETXEN_ROMUSB_ROM_ADDRESS, addr);
> >  	netxen_nic_reg_write(adapter, NETXEN_ROMUSB_ROM_ABYTE_CNT, 3);
> > -	udelay(70);		/* prevent bursting on CRB */
> > +	udelay(100);		/* prevent bursting on CRB */
>
> To prevent PCI write posting issues, you should always do a dummy read
> before
> any delay.

Good point. Thanks.
-Amit
-
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