Hi Tomi, On Wed, Feb 08, 2023 at 05:10:05PM +0200, Tomi Valkeinen wrote: > On 27/01/2023 11:15, Andy Shevchenko wrote: > > On Fri, Jan 27, 2023 at 10:24:04AM +0200, Tomi Valkeinen wrote: > >> On 26/01/2023 12:51, Laurent Pinchart wrote: > >>> On Thu, Jan 26, 2023 at 12:21:06PM +0200, Andy Shevchenko wrote: > >>>> On Thu, Jan 26, 2023 at 10:41:47AM +0200, Tomi Valkeinen wrote: > >>>>> On 25/01/2023 17:27, Andy Shevchenko wrote: > > > > ... > > > >>>>>> But I probably don't understand the ATR structure and what exactly we need to > >>>>>> pass to it, perhaps it also can be replaced with properties (note, that we have > >>>>>> some interesting ones that called references, which is an alternative to DT > >>>>>> phandle). > >>>>> > >>>>> Well, maybe this needs a Linux bus implementation. I'm not that familiar > >>>>> with implementing a bus, but I think that would make it easier to share data > >>>>> between the deserializer and the serializer. A bus sounds a bit like an > >>>>> overkill for a 1-to-1 connection, used by a few drivers, but maybe it > >>>>> wouldn't be too much code. > >>>> > >>>> Have you looked at auxiliary bus (appeared a few releases ago in kernel)? > >>> > >>> As far as I understand, the auxiliary bus infrastructure is meant for > >>> use cases where a single hardware device needs to be split into multiple > >>> logical devices (as in struct device). Platform devices were > >>> historically (ab)used for this, and the auxiliary bus is meant as a > >>> cleaner solution. I'm not sure if it would be a good match here, or if > >>> it would be considered an abuse of the auxiliary bus API. > >> > >> The aux bus docs say "A key requirement for utilizing the auxiliary bus is > >> that there is no dependency on a physical bus, device, register accesses or > >> regmap support. These individual devices split from the core cannot live on > >> the platform bus as they are not physical devices that are controlled by > >> DT/ACPI.", which doesn't sound like a good fit. > > > > Thanks for checking! > > > >> The deserializer and serializers are currently independent devices and > >> drivers (the pdata is the only shared thing), but I think we may need > >> something better here. The devices are more tightly tied together than > >> "normal" video devices, in my opinion, as the serializer is fully controlled > >> by the deserializer (including power). > >> > >> And if we ever want to implement something like power management, we > >> probably need something more than what we have now. Although I don't know > >> how that would be done, as all the peripherals behind the serializer would > >> also lose power... > > > > I believe you have to create a power domain for them and when such device > > is added, the power domain of it should belong to the serialized. > > I was testing this, and got something working. As discussed offline, I'm not sure power domains are the right tool for this. I would model the power supplies as regulators, provided by the deserializer, and acquired by the serializers. If the devices on the remote side are all children of the serializer (which I think they should be), then enabling the regulator in the PM resume handler of the serializer should be all you need. > I have the deserializer introducing a separate power-domain for each RX > port, and the serializer and the sensor both refer to their port's > domain. I can see that the deserializer gets power on/off callbacks > correctly when either serializer or sensor resumes. > > The problem I have now is that while the power comes from the > deserializer and is thus covered with the power domain, the sensor uses > services from the serializer (gpios, clocks, i2c bus), and the > serializer is not woken up when the sensor does runtime-pm resume (the > power domain is powered up correctly when the sensor resumes). Is the sensor not a child of the serializer ? > The serializer creates the i2c adapter to which the sensor is added, so, > afaics, there should be a child-parent relationship there. But maybe I > have something wrong there, or it just doesn't work as I imagine it > would work. You can check the parent/child relationships fairly easily in sysfs. -- Regards, Laurent Pinchart
