On Fri, Jun 28, 2024 at 09:36:57AM GMT, Krzysztof Kozlowski wrote: > On 27/06/2024 18:45, Marc Gonzalez wrote: > > On 27/06/2024 18:25, Conor Dooley wrote: > > > >> On Thu, Jun 27, 2024 at 01:13:03PM +0200, Marc Gonzalez wrote: > >> > >>> TDP158 is an AC-coupled DVI / HDMI to TMDS level shifting Redriver. > >>> It supports DVI 1.0, HDMI 1.4b and 2.0b. > >>> It supports 4 TMDS channels, HPD, and a DDC interface. > >>> It supports dual power supply rails (1.1V on VDD, 3.3V on VCC) > >>> for power reduction. Several methods of power management are > >>> implemented to reduce overall power consumption. > >>> It supports fixed receiver EQ gain using I2C or pin strap to > >>> compensate for different lengths input cable or board traces. > >>> > >>> Features > >>> > >>> - AC-coupled TMDS or DisplayPort dual-mode physical layer input > >>> to HDMI 2.0b TMDS physical layer output supporting up to 6Gbps > >>> data rate, compatible with HDMI 2.0b electrical parameters > >>> - DisplayPort dual-mode standard version 1.1 > >>> - Programmable fixed receiver equalizer up to 15.5dB > >>> - Global or independent high speed lane control, pre-emphasis > >>> and transmit swing, and slew rate control > >>> - I2C or pin strap programmable > >>> - Configurable as a DisplayPort redriver through I2C > >>> - Full lane swap on main lanes > >>> - Low power consumption (200 mW at 6Gbps, 8 mW in shutdown) > >>> > >>> https://www.ti.com/lit/ds/symlink/tdp158.pdf > >>> > >>> Signed-off-by: Marc Gonzalez <mgonzalez@xxxxxxxxxx> > >>> --- > >>> .../bindings/display/bridge/ti,tdp158.yaml | 51 ++++++++++++++++++++++ > >>> 1 file changed, 51 insertions(+) > >>> > >>> diff --git a/Documentation/devicetree/bindings/display/bridge/ti,tdp158.yaml b/Documentation/devicetree/bindings/display/bridge/ti,tdp158.yaml > >>> new file mode 100644 > >>> index 0000000000000..21c8585c3bb2d > >>> --- /dev/null > >>> +++ b/Documentation/devicetree/bindings/display/bridge/ti,tdp158.yaml > >>> @@ -0,0 +1,51 @@ > >>> +# SPDX-License-Identifier: GPL-2.0-only > >>> +%YAML 1.2 > >>> +--- > >>> +$id: http://devicetree.org/schemas/display/bridge/ti,tdp158.yaml# > >>> +$schema: http://devicetree.org/meta-schemas/core.yaml# > >>> + > >>> +title: TI TDP158 HDMI to TMDS Redriver > >>> + > >>> +maintainers: > >>> + - Arnaud Vrac <avrac@xxxxxxxxxx> > >>> + - Pierre-Hugues Husson <phhusson@xxxxxxxxxx> > >>> + > >>> +properties: > >>> + compatible: > >>> + const: ti,tdp158 > >>> + > >>> + reg: > >>> + description: I2C address of the device > >> > >> Is reg not required? How do you communicate with the device if the i2c > >> bus is not connected? Is the enable GPIO enough to operate it in some > >> situations? > >> > >> Otherwise this looks good to me, but given Maxime commented about the > >> complexity of the device, I'm probably out of my depth! > > > > Valid question. > > > > As discussed in my brilliantly expanded commit message (:p) > > the device can be configured in various ways, either through I2C registers > > or by pin strap. We use the device in its default settings, so we don't > > touch any I2C registers, thus I'm not sure the reg property is required. > > But then how would it be represented in the DT? Where / under which parent? > > If this is supposed to be always in I2C bus in DT, then you always need > reg. If you could place it in other place, then your reasoning is valid > - reg is optional. As far as I understood, the device is connected to I2C bus, it just doesn't need to be programmed. So I'd conclude that reg is required. -- With best wishes Dmitry
