On Tue, Nov 13, 2018 at 06:12:37PM +0000, Peter Rosin wrote: > On 2018-11-13 18:24, Russell King - ARM Linux wrote: > > On Tue, Nov 13, 2018 at 01:28:40PM +0000, Peter Rosin wrote: > >> Hi! > >> > >> I'm wondering about some programming details regarding the TDA998x > >> driver... > >> > >> The bindings documentation [1] state that one should fill in the > >> desired register content of the AP_ENA register. However, I cannot > >> find any details anywhere about how one determines what is desired. > >> When I look for data sheets on the Internet, all I find is a "short" > >> data sheet, which is far from enlightening. There are hints about > >> a "full" data sheet in the chapter on legal information of the > >> "short" data sheet. Is the "full" data sheet protected by an NDA > >> or something? That's the only reason I can find for it not being > >> available... > >> > >> Maybe someone with such a "full" data sheet at hand can enlighten > >> me on the workings of this AP_ENA register so that I know what it is > >> that I need to fill in? Since it is so difficult to find this info, > >> maybe it should be added to the binding? > > > > There's various public documents for the TDA998x chips, some of which > > do contain the register programming information - although we don't > > have definitive information for every variant that the driver supports. > > I have looked, and not found anything. Do you have any pointer? For what > chip(s) in the family are there register information? TDA9983B is the main one, but as I say, it doesn't document several registers found in the TDA19988 - we have no definitive register descriptions for this chip. > > Even so, that doesn't give us documentation for this register, so we > > have to resort to code received from other sources. > > > > The AP_ENA register "audio port enable" is one bit per AP signal, from > > the AP0 pin being bit 0, up to the AP7 pin being bit 7. > > Thanks! However, in the "short" sheet for the TDA19988 that I have, there > is this table: > > AP0 WS (word select) > AP1 S/PDIF input I2S-bus channel 0 > AP2 S/PDIF input I2S-bus channel 1 > AP3 I2S-bus channel 2 > AP4 I2S-bus channel 3 > ACLK SCK (I2S-bus clock) > > AP5 through AP7 are nowhere to be found... Right, so only bits 0 to 4 are meaningful. > Should I assume that ACLK is an alias for AP5, and that the register > content should be 0x23 for I2S on channel 0? Or is ACLK not part of > the AP_ENA register at all, so that 0x03 is more likely to be correct? I believe 0x03 as per the example binding in the tda998x document. The example given is from Jean's work for the Dove Cubox which uses a TDA19988, which has both I2S and S/PDIF wired to the TDA19988 - I2S data on AP1, S/PDIF data on AP2. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
