On Tue, May 28, 2024 at 04:50:10PM GMT, Dmitry Baryshkov wrote: > On Tue, May 28, 2024 at 11:17:56AM +0200, Maxime Ripard wrote: > > On Tue, May 28, 2024 at 10:05:50AM GMT, Arnaud Vrac wrote: > > > On 28/05/2024 09:43, Maxime Ripard wrote: > > > > Hi, > > > > > > > > On Mon, May 27, 2024 at 06:03:56PM GMT, Marc Gonzalez wrote: > > > > > From: Arnaud Vrac <avrac@xxxxxxxxxx> > > > > > > > > > > The TI TDP158 is an AC-Coupled HDMI signal to TMDS Redriver supporting > > > > > DVI 1.0 and HDMI 1.4b and 2.0b output signals. > > > > > > > > > > Since it's an I2C-programmable bridge, it could have a proper driver, > > > > > but the default settings work fine, thus simple bridge is sufficient. > > > > > > > > No it doesn't. That bridge supports HDMI 2.0 which means you'll need to > > > > change the TMDS clock ratio when programming a TMDS character rate > > > > higher than 340MHz. And you'll need hotplug support to deal with it > > > > properly too. > > > > > > > > So sorry, you need a real driver there. > > > > > > Hello, this is an HDMI redriver, which simply cleans up the HDMI > > > signal, so no programming is needed to support HDMI 2.0. > > > > I mean, if I'm to trust the datasheet, it is more complicated than that. > > It snoops the DDC bus so it can update the TMDS clock ratio bit if it's > > sent on its input side, but that wouldn't happen with DP for example. > > If I understand correctly, this chip can work in two modes: dummy and > I2C-programmed. In the former case it is fully transparent, including > HPD passthrough, it doesn't require any additional programming, just > Vcc, Vdd and pin straps, etc. And the second mode is a 'brainy' one, > when the chip is fully controlled over I2C. Right, and like I said, the situation is more complicated than "it just does passthrough" like simple-bridge does. > From the Linux standpoint these two modes will use single compat string, > but two distinct drivers: for the former mode is is enough to use > simple-bridge (fixed to support two supplies), while the latter one > needs a proper I2C driver. > > Does that solve your concern? We need to be careful here: if there's two drivers with the same compatible and bus, both will be probed. So we need to take it into account when designing the binding. Maxime
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