On Tue, Jan 19, 2016 at 04:54:30PM +0000, Russell King - ARM Linux wrote:
On Tue, Jan 19, 2016 at 02:40:31PM +0100, Arnaud Pouliquen wrote:
From: Moise Gergaud moise.gergaud@st.com
Add helper function to compute HDMI CTS and N parameters Implementation is based on HDMI 1.4b specification.
You should note that these CTS/N parameters are for where the audio and video clocks are coherent: iow, they are derived from the same source. If they can drift (because they're generated from different sources) then a hardware implementation which automatically calculates CTS is needed.
However, some of the values given in the HDMI specs for CTS are actually two values, because a single value does not specify the audio clock even with the N values given. For these, the values returned will not give an accurate clock - this should also be noted.
Next, does "pixel clock" make sense when you have pixel repetition? Would calling this "tdms_clock" be more accurate to the specification and less mis-leading to users?
It'd also be good to capture some of the above information from Russell in the code so other people don't miss it when using the helpers.