Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
For bugs related to Red Hat Enterprise Linux 5 product line. The current stable release is 5.10. For Red Hat Enterprise Linux 6 and above, please visit Red Hat JIRA https://issues.redhat.com/secure/CreateIssue!default.jspa?pid=12332745 to report new issues.

Bug 509585

Summary: [RHEL 5.3] problems changing coalesce settings <=12us on bnx2x
Product: Red Hat Enterprise Linux 5 Reporter: Flavio Leitner <fleitner>
Component: kernelAssignee: Flavio Leitner <fleitner>
Status: CLOSED DUPLICATE QA Contact: Red Hat Kernel QE team <kernel-qe>
Severity: high Docs Contact:
Priority: high    
Version: 5.3CC: aaswath, agospoda, andriusb, dshaks, jwest, mwagner, sgruszka
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2010-02-09 07:19:15 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 533192    
Attachments:
Description Flags
patch fixing rx coalesce none

Description Flavio Leitner 2009-07-03 18:59:05 UTC
Description of problem:

  Setting to anything <= 12 causes all network traffic to 'disappear',
  cannot ping, telnet, etc.
  Bringing the interface down, then setting to > 12 will correct the issue.


Version-Release number of selected component (if applicable):
  RHEL 5.3 x86_64 (-155 from dzickus tested as well)


How reproducible:
  Always


Relevant code:
static int bnx2x_set_coalesce(struct net_device *dev,
                             struct ethtool_coalesce *coal)
{
       struct bnx2x *bp = netdev_priv(dev);

       bp->rx_ticks = (u16) coal->rx_coalesce_usecs;
       if (bp->rx_ticks > 3000)
               bp->rx_ticks = 3000;
...
       if (netif_running(dev))
               bnx2x_update_coalesce(bp);

and

static void bnx2x_update_coalesce(struct bnx2x *bp)
{
               REG_WR8(bp, BAR_USTRORM_INTMEM +
                       USTORM_SB_HC_TIMEOUT_OFFSET(port, sb_id,
                                                   U_SB_ETH_RX_CQ_INDEX),
                       bp->rx_ticks/12);

Usually a code like that 'rx_ticks/12' means the board register accepts
multiples of 12, so you can configure 0us, 12us, 24us, 36us, 48us, 60us...
Upstream does that too.
Broadcom driver does that too.

I looks like a hardware limitation, though I don't have any detailed
board specification to make sure.

However, it should not stop working because someone tried to configure
a value less or equal 12us.

Comment 5 Flavio Leitner 2009-07-06 17:39:13 UTC
Created attachment 350651 [details]
patch fixing rx coalesce 

Hi,

I've received a feedback from Broadcom on this. The FW supports coalescing
in 12us granularity, and so value of less then 12 should be interpreted as
disabling coalescing.

Could you give a try on the attached patch?

thank you,
Flavio

Comment 16 Stanislaw Gruszka 2010-02-09 07:19:15 UTC
I missed/forgot about that bug. It is duplicate (already solved).

*** This bug has been marked as a duplicate of bug 522600 ***