On Wed, Nov 04, 2020 at 08:46:57AM -0800, Richard Cochran wrote: > On Wed, Nov 04, 2020 at 11:01:49AM -0500, min.li...@renesas.com wrote: > > From: Min Li <min.li...@renesas.com> > > > > Use div_s64 so that the neg_adj is not needed. > > Back in the day, I coded the neg_adj because there was some issue with > signed 64 bit division that I can't recall now. Either div_s64 didn't > exist or it was buggy on some archs... there was _some_ reason. > > So unless you are sure that this works on all platforms, I would leave > it alone.
On the other hand and with all due respect, saying that it may have been 'buggy on some archs back in the day' and then not bringing any evidence is a bit of a strange claim to make. I am actively using div_s64 in drivers/net/dsa/sja1105/sja1105_ptp.c successfully on arm and arm64. We may keep the ptp_clock_info::adjfine procedure as is, and to be copied by everyone, because we can't make sure that it works "on all platforms" (aka "cargo cult"). Or we could waste a few hours from somebody's time, until he figures out how to bisect the IDT 82P33 PTP driver (a driver with 3 patches, and 3 more with Min's series) to find a 1-line change, and then we could find out what the problem you were seeing was. I say waste that guy's time :)
