On Fri, Sep 04, 2026 at 10:22:18AM +0200, Konrad Dybcio wrote: > On 9/3/26 8:26 PM, David Heidelberg via B4 Relay wrote: > > From: David Heidelberg <[email protected]> > > > > Program the ASP RX and TX slot registers from the TDM masks passed by > > the machine driver. Each set bit in a mask names a slot; codec channels > > are assigned to those slots in order, ASPRX1 taking the first RX slot > > and ASPTX1..TX8 the first eight TX slots, with a warning if the mask > > names more slots than the device has channels. > > > > Passing slots == 0 or an empty mask restores the hardware defaults, > > ASPRX1 in slot 0 and ASPTX1..TX8 in slots 0..7. > > > > This lets a machine driver with several amplifiers on one bus, such as > > sdm845 with two CS35L36, put each amplifier on its own RX slot and keep > > their TX slots from colliding. > > > > Assisted-by: Claude:claude-4.6-opus > > Signed-off-by: David Heidelberg <[email protected]> > > --- > > [...] > > > +static int cs35l36_set_tdm_slot(struct snd_soc_dai *dai, > > + unsigned int tx_mask, unsigned int rx_mask, > > + int slots, int slot_width) > > +{ > > + struct cs35l36_private *cs35l36 = > > + snd_soc_component_get_drvdata(dai->component); > > + > > + /* Note: rx/tx is from point of view of the CPU end */ > > + if (!slots || !rx_mask) > > + rx_mask = BIT(0); /* ASPRX1 in slot 0 */ > > + > > + if (!slots || !tx_mask) > > + tx_mask = GENMASK(7, 0); /* ASPTX1..8 in slots 0..7 */ > > + > > + cs35l36_mask_to_slots(cs35l36, rx_mask, CS35L36_ASP_RX1_SLOT, 1); > > GPT says: > > Findings > 1. High: patch 5 makes the TDM RX slot compete with the codec’s Input Mux > control. > cs35l36_set_tdm_slot() programs CS35L36_ASP_RX1_SLOT with a > six-bit TDM slot value in patch 5. That register’s bit 0 is > already exposed as the Input Mux DAPM control: > - sound/soc/codecs/cs35l36.c:588 defines the control from > CS35L36_ASP_RX1_SLOT, shift 0. > - sound/soc/codecs/cs35l36.c:583-586 defines its values as RX1 and RX2.
This is a fair point, although I am inclined to say that using an ALSA control for this is definitely not a good thing to do. I would be tempted to say just remove the alsa control, now we have a proper TDM callback. But probably also fine to ignore the control for now. It only becomes a problem if user-space starts tweaking the control and to some extent that is on the person changing the control. Thanks, Charles
