Michael Zoran <mzoran@xxxxxxxxxxxx> writes: > On Tue, 2017-03-21 at 10:34 -0700, Eric Anholt wrote: >> Michael Zoran <mzoran@xxxxxxxxxxxx> writes: >> >> > On Mon, 2017-03-20 at 10:22 -0700, Eric Anholt wrote: >> > > Michael Zoran <mzoran@xxxxxxxxxxxx> writes: >> > > >> > > > > > Since the API is completely documented, I see no reason we >> > > > > > or >> > > > > > anybody >> > > > > > couldn't essentially rewrite the driver while it's in >> > > > > > staging. I >> > > > > > just >> > > > > > think it would be best for everyone if the new version was >> > > > > > a >> > > > > > drop >> > > > > > in >> > > > > > replacement for the original version. Essential an >> > > > > > enhancement >> > > > > > rather >> > > > > > then a competitor. >> > > > > >> > > > > I think my comments weren't fundamental changes, but you >> > > > > surely >> > > > > mean >> > > > > the devicetree ABI? I like to see this driver ASAP out of >> > > > > staging >> > > > > and >> > > > > i'm not interested to maintain 2 functional identical driver >> > > > > only >> > > > > to >> > > > > keep compability with the Foundation tree. Currently i'm >> > > > > afraid >> > > > > that >> > > > > we build up many drivers in staging, which need a complete >> > > > > rewrite >> > > > > later if they should come out of staging. It would be nice if >> > > > > we >> > > > > could avoid the situation we have with the thermal driver. >> > > > > >> > > > > Stefan >> > > > >> > > > The API I'm talking about here is the mailbox API that is used >> > > > to >> > > > talk >> > > > to the firmware. The numbers and structures to pass are >> > > > documented. >> > > > Nothing prevents anybody from rewriting this driver and >> > > > submitting >> > > > it >> > > > to the appropriate subsystems. It's certainly small enough. >> > > > >> > > > If you really want working thermal or cpu speed drivers today, >> > > > nothing >> > > > stops anybody from submitting the downstream drivers after >> > > > doing >> > > > some >> > > > minor touchups and submitting them to staging. That would at >> > > > least >> > > > get >> > > > things working while people argue about what the correct DT >> > > > nodes >> > > > should be. >> > > > >> > > > I would also like to point out that the RPI 3 has been out for >> > > > over >> > > > a >> > > > year and nobody has been able to get working video out of it >> > > > through >> > > > VC4 on a mainline tree. At least until now. So I'm not sure >> > > > the >> > > > best >> > > > way to go is for the expander driver to go under the GPIO >> > > > subtree. >> > > >> > > Excuse me? Display works fine on my Pi3. VC4 uses DDC to probe >> > > for >> > > connection when the GPIO line isn't present in the DT. >> > >> > Just a FYI, Eric Anholt has offically announced support for VC4 for >> > HDMI on mainline Linus build without any support from the expander >> > on >> > the RPI 3. >> > >> > Sounds like this particular driver isn't needed then, correct? >> >> That's the HDMI audio that just landed. HDMI has been working on the >> pi3 since 9d44abbbb8d530e8cc97d71ffcbc0ff3b5553c62. >> >> In the absence of a GPIO line for hotplug detect, we use DDC, which >> is >> slower and throws an error in dmesg when the probe happens but HDMI >> is >> disconnected. As such, having a GPIO driver would improve things for >> people. > > > Would a non DT based solution be outside the realm of possibilities? I > wrote a very simple library that emulates vcgencmd from the kernel. > One of the commands for vcgencmd is to query the HDMI hotplug status. > It's sort of semi documentated on the web. The vcgencmd library works, > but I haven't tested if the virtualized hotplug info from the command > output is correct in all cases. > > What I'm thinking is I could package this in a single file library that > would get put in upstream, but it would only support 1 command only. To > query the virtual hotplug status. > > The only thing is you would need to take a dependency from VC4 to > vchiq/vc04_services. It would get VC4 working better on upstream, but > it would mean taking a dependency from VC4 to vc04_services and the > stagging tree(with all that imples). > > I think this may be a better solution then arguing with the DT folks on > this expander driver that isn't being directly controlled. > > What do you think? Not interested. We should expose the full GPIO expander using the firmware's GPIO expander interfaces, which is a more generally useful solution.
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