From mboxrd@z Thu Jan 1 00:00:00 1970 From: Siva Reddy Kallam Subject: Re: [PATCH net 1/2] tg3: Fix for diasllow rx coalescing time to be 0 Date: Fri, 5 Aug 2016 11:14:55 +0530 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Rick Jones , David Miller , Netdev , Prashant Sreedharan , Satish Baddipadige To: Michael Chan Return-path: Received: from mail-qk0-f170.google.com ([209.85.220.170]:35502 "EHLO mail-qk0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752058AbcHEFo5 (ORCPT ); Fri, 5 Aug 2016 01:44:57 -0400 Received: by mail-qk0-f170.google.com with SMTP id x185so61251997qkc.2 for ; Thu, 04 Aug 2016 22:44:57 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Aug 4, 2016 at 3:45 AM, Michael Chan wrote: > On Wed, Aug 3, 2016 at 9:04 AM, Rick Jones wrote: >> >> Should anything then happen with: >> >> /* No rx interrupts will be generated if both are zero */ >> if ((ec->rx_coalesce_usecs == 0) && >> (ec->rx_max_coalesced_frames == 0)) >> return -EINVAL; >> >> >> which is the next block of code? The logic there seems to suggest that it >> was intended to be able to have an rx_coalesce_usecs of 0 and rely on packet >> arrival to trigger an interrupt. Presumably setting rx_max_coalesced_frames >> to 1 to disable interrupt coalescing. >> > > I remember writing this block of code over 10 years ago for early > generations of the chip. Newer chips seem to behave differently and > rx_coalesce_usecs can never be zero. So this block can be removed now > that the condition can never be true. We should probably leave a > comment there for future reference. Thanks Rick for identifying this. Thanks Michael for your inputs. I will submit a patch with removal of this block of code and add a comment for future reference.