On 17.09.2015 01:18, Russell King - ARM Linux wrote:

On Wed, Sep 16, 2015 at 02:56:57PM -0700, Doug Anderson wrote:

quoted

Yes, I'd expect 100kHz and 400kHz.

I agree that 50ms is non-trivial, but it's also not something you're
doing lots of.  I'd expect that the EDID is read over this channel at
cable plugin time and then not used much after that.  Adding an extra
40ms (10ms vs 50ms) before we can access the TV doesn't seem terrible
for compatibility.

Doing a quick scan for what others in mainline do:

A few can be found with:

$ git grep -A3 hdmiddc | grep clock-freq
arch/arm/boot/dts/stihxxx-b2120.dtsi-
clock-frequency = <100000>;
arch/arm/boot/dts/tegra30-apalis.dtsi-          clock-frequency = <100000>;
arch/arm/boot/dts/tegra30-beaver.dts-           clock-frequency = <100000>;
arch/arm/boot/dts/tegra30-colibri.dtsi-         clock-frequency = <100000>;

This is a sure way to propagate a bug.

I said in a previous email that you need to check the HDMI and CEA
specs.  I've done this, and HDMI 1.3a specifies a maximum SCL clock
rate of 100kHz.

So that's settled then.  100kHz is must be.  Using 400kHz is out of
specification.

FYI I've managed to measure SCL on iMX6, fast mode stands for 333KHz and
standard mode stands for 100KHz, therefore I'll set the latter mode.

--
With best wishes,
Vladimir