Hi, * Jiri Slaby <jirislaby@xxxxxxxxxx> [221124 06:53]: > Hi, > > I am returning to v2, as I managed to read only v3 and only now. But here > was already the point below. > > On 27. 06. 22, 15:48, Tony Lindgren wrote: > > > > Considering the above, let's improve the serial core layer so we can > > > > manage the serial port controllers better. Let's register the controllers > > > > with the serial core layer in addition to the serial ports. > > > > > > Why can't controllers be a device as well? > > > > The controllers are devices already probed by the serial port drivers. > > What's missing is mapping the ports (as devices based on the comments > > above) to the controller devices. I don't think we need another struct > > device for the serial controller in addition to the serial port driver > > device and it's child port devices. > > To be honest, I don't like the patch (even v3). We have uart_state which I > already hate and now we have another structure holding *some* other info > about a serial device (apart from uart_port). It's mess already and hard to > follow, esp. to newcomers. Yup the serial code sure is hard to follow.. > AFAIU, what Greg suggests would be: > > PCI/platform/acpi/whatever struct dev > -> serial controller 1 struct dev > -> serial port 1 struct dev (tty_port instance exists for this) > -> serial port 2 struct dev (tty_port instance exists for this) > -> ... > -> serial controller 2 struct dev > -> serial port 1 struct dev (tty_port instance exists for this) > -> serial port 2 struct dev (tty_port instance exists for this) > -> ... Oh you want the serial controller struct device as a child of the hardware controller struct device. Yeah that makes sense to put it there. I was kind of thinking we want the port devices be direct children of the hardware struct device, but I guess there is no such need. > And you are objecting that mostly (or in all cases?), there will never be > "serial controller 2"? I'm was not aware of the need for multiple serial port controllers connected to a single hardware controller struct device. Is there an example for that somewhere? Not that multiple serial controller struct devices matters with your suggestion, just wondering. > But given your description, I believe you need it anyway -- side note: does > really the PM layer/or you need it or would you be fine with "serial port N" > dev children? But provided you don't have the controller, you work around it > by struct serial_controller. So what's actually the point of the workaround > instead of sticking to proper driver model? With the workaround you seem you > have to implement all the binding, lookup and such yourself anyway. And that > renders the serial even worse :P. Let's do the reverse instead. To me it seems your suggestion actually makes things easier for runtime PM :) We can just enable runtime PM for the serial controller struct device without tinkering with the parent hardware controller struct device. > The only thing I am not sure about, whether tty_port should be struct dev > too -- and if it should have serial port 1 as a parent. But likely so. And > then with pure tty (i.e. tty_driver's, not uart_driver's), it would have > PCI/platform/acpi/whatever as a parent directly. That seems like a separate set of patches, no? Or is there some need right now to have some child struct device as a direct child of the hardware controller struct device? > In sum, the above structure makes perfect sense to me. There has only been > noone to do the real work yet. And having tty_port was a hard prerequisite > for this to happen. And that happened long time ago. All this would need a > lot of work initially¹⁾, but it paid off a lot in long term. > > ¹⁾I know what I am writing about -- I converted HID. After all, the core was > only 1000 lines patch (cf 85cdaf524b7d) + patches to convert all the drivers > incrementally (like 8c19a51591). Cool, thanks for your suggestions. Regards, Tony
