Re: [PATCH net 1/2] tg3: Fix for diasllow rx coalescing time to be 0

On Thu, Aug 4, 2016 at 3:45 AM, Michael Chan [off-list ref] wrote:

On Wed, Aug 3, 2016 at 9:04 AM, Rick Jones [off-list ref] wrote:

quoted

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.