On 09/09/24 15:20, Tomi Valkeinen wrote: > On 09/09/2024 12:31, Aradhya Bhatia wrote: >> Hi, >> >> Thank you, Francesco and Max, for testing and reporting this! >> >> On 09/09/24 13:45, Tomi Valkeinen wrote: >>> Hi, >>> >>> On 06/09/2024 14:43, Francesco Dolcini wrote: >>>> +Max >>>> >>>> Hello Aradhya, >>>> >>>> On Tue, Jul 16, 2024 at 02:12:44PM +0530, Aradhya Bhatia wrote: >>>>> The addition of the 2nd OLDI TX (and a 2nd DSS in AM62Px) creates a >>>>> need >>>>> for some major changes for a full feature experience. >>>>> >>>>> 1. The OF graph needs to be updated to accurately show the data flow. >>>>> 2. The tidss and OLDI drivers now need to support the dual-link and >>>>> the >>>>> cloned single-link OLDI video signals. >>>>> 3. The drivers also need to support the case where 2 OLDI TXes are >>>>> connected to 2 different VPs - thereby creating 2 independent >>>>> streams >>>>> of single-link OLDI outputs. >>>> >>>> Have you considered/tested the use case in which only single link is >>>> used? >>>> You do not mention it here and to me this is a relevant use case. >>>> >>>> There is a workaround for this (use option 2, cloned, even if >>>> nothing is >>>> connected to the second link), but this seems not correct. >> >> I agree. The whole idea behind the series is to be able to accurately >> describe the hardware. Putting the devicetree in clone mode in order to >> get the single-link mode working is far from ideal. > > Btw, with the fw_devlink=off hack, and removing the second link from k3- > am625-sk-microtips-mf101hie-panel.dtso, is still not enough, as the k3- > am62-main.dtsi contains the ti,companion-oldi property which makes the > driver think it's a cloning case. Yes! > > So, I think, either the ti,companion-oldi and ti,secondary-oldi should > only be set in the overlay when setting up cloning/dual-link, or the > companion-oldi property shouldn't actually make a difference, and the > selection between clone and single-link should be done via some other > means. Yep, those properties need to be set in the overlay file, and not in the k3-am62-main.dtsi like it is the case in ti-6.6. > >>>> We (Max in Cc here) noticed that this specific use case is broken on >>>> your downstream v6.6 TI branch. >> >> Yes, it was been brought to my attention that the single-link usecase is >> not working over the downstream ti-6.6 kernel. As I have since >> discovered, it's not working on this series either. >> >> For some reason, the supplier-consumer dependency between the OLDI and >> the panel devicetree nodes is not getting flagged as `FWLINK_FLAG_CYCLE` >> in cases of single-link configuration. >> >> This flag allows the panel driver to continue to probe without waiting >> for the OLDI driver (panel's supplier). Absence of the flag getting set >> is causing these drivers to keep deferring probe in an endless cycle. >> >> Even with the flag, the OLDI (and tidss) cannot complete probe until the >> panel driver is probed and ready. That is because the OLDI (and tidss) >> need the panel to continue with the bridge-chain creation. >> >> However, over with the dual-lvds configuration (and as Francesco has >> now mentioned the clone configuration as well), the flag gets set by >> default, and everything works. >> >> This is what the debug has led to, so far. > > Yes, I came to the same conclusion with my debug. > >>> >>> What if you set "fw_devlink=off" kernel boot parameter? >>> >> >> Yes! I haven't tested it, but it seems that this will bypass the >> supplier check and let the panel probe continue. >> >> >> Tomi, any idea, why is this issue happening only for single-link in the >> first place? It seems as if having 2 ports inside the panel devicetree >> lets the probe mechanism recognize the circular dependency and ignore >> the supplier OLDIs? > > I have to say I have no idea... > > I don't really understand the devlink code here, but I'm guessing that > the "cycle" part comes from the fact that with a media graph we have > links (remote-endpoint) both ways in the DT data. So it's not possible > to say which side is the consumer, which one is the supplier. Thus, it's > marked as a cycle and, I think, basically ignored for the probing purpose. Okay! I am not too sure about the devlink code either, but this reasoning makes sense. > > But why not here? I can see the links being created both ways: > > /display Linked as a fwnode consumer to /bus@f0000/dss@30200000/oldi- > txes/oldi@0 > /bus@f0000/dss@30200000/oldi-txes/oldi@0 Linked as a fwnode consumer > to /display > > but it's never marked as a cycle. Yes, this matches my observations. > >> This is the function where the difference comes down to, by the way - >> __fw_devlink_relax_cycles(), per my knowledge. I am still on my way to >> understand what exactly it is doing and why is it not relaxing the >> single-link case. > > Yep. The answer is probably somewhere there =). > Alright! We have an interesting problem in our hands now. =) Regards Aradhya
