On 11/18/14 18:00, Russell King - ARM Linux wrote: > On Tue, Nov 18, 2014 at 05:39:30PM +0000, Andrew Jackson wrote: >> On HDMI, the audio data are carried across the HDMI link which is >> driven by the TDMS clock. The TDMS clock is dependent on the video pixel >> rate. >> >> This patch sets the denominator (Cycle Time Stamp) appropriately >> allowing the driver to send audio to a wider range of HDMI sinks >> (i.e. monitors). > > This is actually pointless, because we don't use "manual" CTS mode. > > If the clocks for the video and audio are coherent, then you can program > both the N and CTS values to allow the sink to properly recover the > synchronous audio clock. > > However, in most cases, the audio and video clocks are not coherent, and > since the recovered audio clock has to match the source audio clock, the > only way this can be done is by the TDA998x (or in fact other HDMI > encoder) to measure the audio clock rate and generate the CTS value > itself. > > This is the mode we drive the TDA998x - so the programmed CTS value is > irrelevant. My apologies for the noise: I originally created the patch when one of the monitors with which I was working wouldn't play sound as expected. However, I now find that the monitor plays sound with or without the patch so it must have been something else. I'd missed the significance of the "auto CTS" comment a few lines earlier (partly because I've no datasheet on the TDA998x). Andrew _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
