Hi Richard, On 08 Dec 2014, at 13:33, Richard Cochran <richardcoch...@gmail.com> wrote: […] > Because providing corrections in-kernel will be spotty at best, maybe > it better just to say, Linux drivers do *not* correct these delays. At > leas that makes things consistent. Otherwise end users will have to > comb through the kernel source in order to figure out whether the > corrections in the data sheet are implemented or not. > >> There >> should also be a standardised mechanism to update correction offsets >> at runtime as a fallback mechanism when defaults are not good >> enough. > > Do you mean a standard method in the kernel for drivers to use?
Yes, I was thinking it would allow to query if the driver supports this feature and get/set current offsets. This way user-mode applications would know if the driver already corrects timestamps (and by how much) and decide if it should apply its own corrections or not. I see your point but that kind of argument could be applied to most opt-in driver features. No extra work would be required for drivers which do not opt-in. Regardless of where the correction is applied there should be a way to query/set the currently applied offsets at runtime. I’d think the obvious choice for linuxptp would be an implementation specific management interface message. >> (2) For some reason I would prefer (but not strongly) adding a >> signed correction offset in both the egress and ingress directions >> instead of adding in one direction and subtracting in the other. > > So far, the data sheets I have seen give these corrections as positive > numbers for both egress and ingress delays. The idea was to allow the > user to simply enter the values from the data sheet into the > configuration file. ACK, good point. > > Thanks, > Richard ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
