Hi Jerome, On Mon, Oct 4, 2021 at 11:17 PM Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> wrote: [...] > > This bit could also be a remain of an older design, not really connected > > to anything meaningful. It would not be the first time. > > > > The AIU looks like an IP that has evolved a lot over the years, not always > > in a coordinated fashion. Some scenario are well supported and easy, > > others seem to require a magic spell. > > > > Last (but not least), in AML vendor kernel, the only time this bit poked > > is around 8ch support (1 for 8ch, 0 otherwise) ... I have no idea why. > The 32-bit SoCs use SPDIF to feed 2-channel audio to the HDMI TX > controller and I2S to feed 8-channel audio to the HDMI TX controller. > It seems that Amlogic stopped this for (at least some) 64-bit SoCs. > > My testing results indicate that AIU_CLK_CTRL_MORE[6] is still relevant. > I can do another round of testing with various combinations of > AIU_CLK_CTRL_MORE[6] and AIU_HDMI_CLK_DATA_CTRL register values. > If you want me to test any specific combinations then please let me know. I have tested various combinations, see the attached result file (which can be viewed with "column -t /path/to/results.txt"). The short summary is that... ...I2S output requires: AIU_HDMI_CLK_DATA_CTRL[1:0] = 0x2 AIU_HDMI_CLK_DATA_CTRL[5:4] = 0x2 AIU_CLK_CTRL_MORE[6] = 0x1 ...SPDIF output requires: AIU_HDMI_CLK_DATA_CTRL[1:0] = 0x2 AIU_HDMI_CLK_DATA_CTRL[5:4] = (any) AIU_CLK_CTRL_MORE[6] = 0x1 My test consisted of running speaker-test -c2 and playing an mp3 with ffplay on an Odroid-C1. In other words: this confirms what we have suspected before. What is your suggestion on how to model these muxes in the driver? In the meantime I finally understood what #sound-dai-cells = <1>; does thanks to your previous hints. With that I can wire up the I2S and SPDIF inputs to the HDMI TX controller's "HDMI codec". Many thanks again for this hint! Best regards, Martin
AIU_HDMI_CLK_DATA_CTRL[1:0] AIU_HDMI_CLK_DATA_CTRL[5:4] AIU_CLK_CTRL_MORE[6] I2S SPDIF (CTRL_CLK_SEL) (CTRL_DATA_SEL) (AMCLK) (I2S) (SPDIF) 0x0 0x0 0x0 silence silence 0x0 0x0 0x1 silence silence 0x2 0x0 0x0 silence playback 0x2 0x0 0x1 silence silence 0x2 0x2 0x1 playback silence 0x2 0x2 0x0 silence playback
