On Sun, Mar 13, 2022 at 04:07:24PM +0100, Andrew Lunn wrote: > On Sat, Mar 12, 2022 at 06:46:46PM -0800, Richard Cochran wrote: > > On Sat, Mar 12, 2022 at 09:04:31PM +0100, Andrew Lunn wrote: > > > Do these get passed to the kernel so the hardware can act on them, or > > > are they used purely in userspace by ptp4l? > > > > user space only. I'm wondering if one-step will work if these correction values are not applied to HW. > > > If they has passed to the kernel, could we provide a getter as well as > > > a setter, so the defaults hard coded in the driver can be read back? > > > > Any hard coded defaults in the kernel are a nuisance. > > > > I mean, do you want user space to say, > > > > "okay, so I know the correct value is X. But the drivers may offer > > random values according to kernel version. So, I'll read out the > > driver value Y, and then apply X-Y." > > > > Insanity. > > No, i would not suggests that at all. > > You quoted the man page and it says the default it zero. If there was > an API to ask the driver what correction it is doing, and an API to > offload the delay correction to the hardware, i would simply remove > the comment about the default being zero. If these calls return > -EOPNOTSUPP, then user space stays the same, and does actually use a > default of 0. If offload is supported, you can show the user the > current absolute values, and allow the user to set the absolute > values. This sounds like a good approach to me (but I know it is not my opinion you are asking for). In all cases, if there is a desire to have such APIs, and let drivers advertise default compensation values in this way, we can work on that. > Anyway, it is clear you don't want the driver doing any correction, so > lets stop this discussion. > > Andrew -- /Allan
