On Mon, Apr 14, 2025 at 04:07:23PM +0200, Geert Uytterhoeven wrote: > Hi Greg, > > On Mon, 14 Apr 2025 at 11:32, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Mon, Apr 14, 2025 at 11:23:34AM +0200, Thierry Bultel wrote: > > > Le 14/04/2025 à 10:58, Greg KH a écrit : > > > > On Mon, Apr 14, 2025 at 07:54:12AM +0000, Thierry Bultel wrote: > > > > > > From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > > On Thu, Apr 03, 2025 at 11:29:12PM +0200, Thierry Bultel wrote: > > > > > > > --- a/include/uapi/linux/serial_core.h > > > > > > > +++ b/include/uapi/linux/serial_core.h > > > > > > > @@ -231,6 +231,9 @@ > > > > > > > /* Sunplus UART */ > > > > > > > #define PORT_SUNPLUS 123 > > > > > > > > > > > > > > +/* SH-SCI */ > > > > > > > +#define PORT_RSCI 124 > > > > > > Why do you need to tell userspace about this specific port? Is that a > > > > > > hard requirement that your userspace tools require? If not, please don't > > > > > > export this here. > > > > > This point has been discussed with Geert and Wolfram. > > > > > We cannot use PORT_GENERIC for this IP, and adding the new type > > > > > is just keeping consistent with the sh-sci driver. > > > > But, why does userspace need to know this number? And why doesn't > > > > PORT_GENERIC work? > > > > > > The reason is that the sh-sci driver discriminates internally between port > > > types. > > > There are number of locations when it checks for PORT_SCI, PORT_SCIF, > > > PORT_SCIFA... > > > > That is internal to the kernel, not external, right? > > Indeed. > > > > T2H SCI needs special handling, too, that is the reason why PORT_GENERIC > > > cannot work. I just therefore added this new type. > > > > Again, why does userspace need to know this? > > I guess userspace does not need to know about this (does userspace > actually care about any of these values, except for PORT_8250 and > friends?). > > However, traditionally PORT_* has been used as the differentiator > for serial port types in most drivers in the kernel (incl. sh-sci.c) > as well. Just two drivers use PORT_GENERIC, and these are the ones > that came with the introduction of PORT_GENERIC. Since the rsci driver > is not a new driver, but a sub-driver of the existing sh-sci driver, > I think it warrants keeping on using the type field, like before. Else > it will have to become even more complex than it already is. > > Note I am fine with using a non-uapi value. Is there a PORT_* number > range meant for internal (non-uapi) use? We can just start putting them in a non-uapi file so that we don't have to keep adding things to userspace that never needs it. thanks, greg k-h
