Hi Krzysztof, On Thu, Jun 25, 2026 at 10:23:54AM +0200, Krzysztof Kozlowski wrote: > On 25/06/2026 06:53, Dmitry Torokhov wrote: > > On Wed, Jun 24, 2026 at 04:37:25PM +0200, David Heidelberg wrote: > >> On 24/06/2026 06:28, Dmitry Torokhov wrote: > >>> Hi David, > >>> > >>> On Sun, Jun 21, 2026 at 07:11:45PM +0200, David Heidelberg wrote: > >>>> On 28/05/2026 00:13, David Heidelberg wrote: > >>>>> On 27/05/2026 23:56, Dmitry Torokhov wrote: > >>>>>> Hi David, > >>>>>> > >>>>>> On Sat, May 23, 2026 at 11:45:35AM +0200, David Heidelberg via B4 > >>>>>> Relay wrote: > >>>>>>> From: David Heidelberg <[email protected]> > >>>>>>> > >>>>>>> We know the driver is reporting s3706b, introduce the compatible so we > >>>>>>> can more easily introduce quirks for weird touchscreen replacements in > >>>>>>> followup series. > >>>>>>> > >>>>>>> Reviewed-by: Konrad Dybcio <[email protected]> > >>>>>>> Signed-off-by: David Heidelberg <[email protected]> > >>>>>>> --- > >>>>>>> arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi | 2 +- > >>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>>>>>> > >>>>>>> diff --git a/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi > >>>>>>> b/arch/ arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi > >>>>>>> index 6b7378cf4d493..148164d456a5a 100644 > >>>>>>> --- a/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi > >>>>>>> +++ b/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi > >>>>>>> @@ -475,17 +475,17 @@ bq27441_fg: bq27441-battery@55 { > >>>>>>> }; > >>>>>>> }; > >>>>>>> &i2c12 { > >>>>>>> status = "okay"; > >>>>>>> clock-frequency = <400000>; > >>>>>>> synaptics-rmi4-i2c@20 { > >>>>>>> - compatible = "syna,rmi4-i2c"; > >>>>>>> + compatible = "syna,rmi4-s3706b", "syna,rmi4-i2c"; > >>>>>> > >>>>>> So I believe we established that this device (s3706b) does not in fact > >>>>>> implement rmi4 protocol properly. Why do we have "syna,rmi4-i2c" as a > >>>>>> fallback? Shouldn't it be just "syna,rmi4-s3706b"? > >>>>> > >>>>> The vendor supplies s3706b which does implement the RMI4 properly. > >>>>> > >>>>> The 3rd party replacement impersonating original parts may not implement > >>>>> it properly, but I don't address this issue in this initial submission. > >>>>> > >>>>> With this compatible we know which original part is used by the vendor > >>>>> and installed in the phones, so later we can deduct specific sequences > >>>>> for the replacement aftermarket parts to keep phone touchscreen working > >>>>> same as they do on Android without affecting other devices. > >>>> > >>>> Hello Dmitry. > >>>> > >>>> May I ask what is currently preventing this series from moving forward? > >>>> > >>>> The first version was posted in 2023 [1]. I picked it up again in 2025 > >>>> [2] > >>>> and am now on the 9th iteration (this patchset). At this point, the > >>>> series > >>>> has been under discussion for well over a year, with relatively little > >>>> feedback and increasingly long gaps between review rounds. > >>>> > >>>> The current approach is based on the guidance I have received so far, > >>>> including suggestions from the device-tree maintainers. When concerns > >>>> were > >>>> raised, I tried to address them and rework the series accordingly. > >>>> > >>>> What I am struggling with is understanding what specific issue still > >>>> needs > >>>> to be resolved before these patches can be accepted. If there are > >>>> remaining > >>>> requirements, objections to the approach, or technical concerns that I > >>>> have > >>>> not addressed, I would appreciate having them stated explicitly so I can > >>>> work on them. > >>>> > >>>> I also split out the straightforward, self-contained changes in the hope > >>>> that at least those could progress independently while I continued > >>>> working > >>>> on any follow-up requirements. However, even those patches do not appear > >>>> to > >>>> be moving forward. > >>>> > >>>> Could you please clarify what outcome you would like to see from this > >>>> series, and what concrete changes would be required to get it accepted? > >>> > >>> I am still confused about how you want to differentiate between the full > >>> RMI4 support vs the OnePlus flavor. The "syna,rmi4-s3706b", as you > >>> mentioned, implements RMI4 protocol properly, so we do not need to > >>> actually have it documented neither in binding nor in DTS. > >> > >> --- part 1 --- > >> > >> This series addresses identification within device-tree. It's normal > >> recommended practice. > >> > >> If we know, the device ships specific, but **compliant** variant, we just > >> put it as compatible = "more-specific", "less-specific"; in this case > >> "syna,rmi4-s3706b", "syna,rmi4-i2c" > >> > >> This approach is used everywhere. This has nothing to do with after-market > >> parts. > > > > We do this in many cases, sometimes when a part has different timings or > > maybe additional functionality compared to the base model. > > Generic expectation is to have always dedicated front compatible for > every device. rmi4-i2c is not really specific enough, more like a > family, thus a specific device compatible is essential by the DT rules.
Essential in what way? What will break if such compatible is not there? We have lived without it for many years and will continue live happily without it for years to come. We keep having this conversation each time there is self-describing protocol that does not require knowledge of a specific part number: i2c-hid, rmi4, spi-hid coming over soon. We might need a device-specific compatible if we need to implement particular power on sequence/adjust timings, and that's when it starts making sense to introduce one. > > It does not matter if that specific compatible is ever used. > > > > > How does this new compatible for controller that fully implements RMI4 > > protocol help here? > > It does not matter. This is a different device, thus it needs > front-specific compatible. Different from what? $ git grep syna,rmi4 -- arch/ | wc -l 43 Do you have plans to list each and every chip currently covered by syna,rmi4* ? > > Also, the commit msg actually did mention how this helps: allowing > further quirks (I did not verify that in practice, but explanation is > plausible). Well, the devil is in the details. And that is what I am trying to understand. > > > > >> > >> --- part 2 (irrelevant for this series) --- > >> > >>> > >>> The issue you have with after-market parts that are not compliant and we > >>> need to figure out how to deal with them. Inside the driver I > >> > >> As was suggested by device-tree folks, this is the first step, there isn't > >> better one available. If there is, please suggest one, and I'll apply it. > > > > Was it clearly communicated to DT folks that the compatible you are > > adding is fully compatible with the base "syna,rmi4-i2c" but other ones > > will not be compatible? > > That was not communicated but also did not have to. You can install in > your board whatever you wish, e.g. replacing foo device with bar being > something completely different and incompatible. Does not matter really > if this is after-market or a person just swapped things. > > DT does not solve that problem simply, because we describe static > hardware configuration. But the core issue that David is trying to solve is the fact that these headsets do not work well with aftermarket parts with the upstream kernels. It is not a theoretical problem for him, it is something that he's been trying to solve for a while. However from my POV I need to make sure the changes to the driver do not affect or limit well-behaved devices implementing RMI4 protocol properly. > > > > >> > >>> essentially need a"incomplete protocol" flag that we can use to > >>> implement additional checks or skip known to be not implemented > >>> functions/queries. In DT we could introduce something like > >>> "oneplus,rmi4-i2c" that is decidedly not compatible with "syna,rmi4-i2c" > >>> and neither one should be a fallback for the other. > >>> > >>> This of course needs buy-in from DT maintainers. > >> > >> As you can see, this still holds Acked-by and Reviewed-by from the relevant > >> people - Krzysztof and Konrad. > > > > I see that but the commit does not explain how exactly you are planning > > to deal with knockoffs. > > I think it does not have to. David does not need to solve all possible > problems. He is solving his problems and not preventing the other > problems to be solved in the future. Unless you expect that the second > part - future problems - will be blocked by this code. Well, as I mentioned above my understanding is that David really wants to solve the issue with after market parts not working properly. > > But then I think no one ever solved in DT a problem of replacement of > valid parts with after-market incompatible parts. Therefore I do not > even know what solution I could suggest to David. > > > > >> > >>> > >>> Does this make sense? > >> > >> For the scope we're discussing it doesn't seems so. > >> > >> This discussion should be associated with the last revision of the full > >> series I sent 3 months ago. We're in very unflattering state, where: > >> > >> 2018 - these aftermarket touchscreen worked on Android well enough for > >> people to have working touch (let's say with slightly worse experience then > >> the original). > >> > >> 2026 in the mainline, we cannot even more forward and report to > >> user-space > >> there is aftermarket non-compliant piece of hardware installed. > >> > >> Actionable steps I suggest after this series lands: > >> > >> 1. don't do any changes, but since we know what 3rd party touchscreen do > >> incorrectly deviating from the standard, REPORT it to the userspace, so > >> USER > >> know, their device (phone/tablet) doesn't have original part. > >> > >> 2. then figure out, IF we can reasonably well workaround it and HOW to do > >> it > >> > >> These two steps present some progress which could be discussed and could > >> lead us somewhere, what do you think? > > > > So since we know that these devices can come with controllers that do > > not implement RMI4 fully, can we: > > > > 1. Establish a new compatible that is separate from syna,rmi4-i2c? As I > > mentioned, it could be oneplus,rmi4-i2c or event a concrete controller > > vendor,id combo. The point that it should be completely separate from > > the current compatible and not use the current compatible as a fallback. > > Board/machine level compatible already gives you that. > after-market-incompatible-parts is not a problem of this s3706b, if I > understood correctly. It feels to me more of a problem of the board: > people install into this board some incompatible replacement parts. So is the suggestion to check if the board matches "oneplus,enchilada", "oneplus,fajitas" with of_machine_compatible_match()? > > I would understand that this is not a board/machine level problem, if > multiple different boards with s3706b were affected. Is this the case? David? Thanks. -- Dmitry
