Re: [PATCH v5 3/4] ALSA: cs35l41: Add shared boost feature

[Lucas Tanure]

On 20-02-2023 19:25, David Rhodes wrote:
> On 2/12/23 03:28, Lucas Tanure wrote:
> > On 11-02-2023 17:06, Charles Keepax wrote:
> > > On Fri, Feb 10, 2023 at 02:39:56PM +0000, Lucas Tanure wrote:
> > > > On 10-02-2023 13:43, Charles Keepax wrote:
> > > > > On Fri, Feb 10, 2023 at 09:19:41AM +0000, Lucas Tanure wrote:
> > > > > > + {CS35L41_MDSYNC_EN,        0x00001000},
> > > > > David's internal patch appears to set 0x3000 on the active side,
> > > > > not sure where that difference snuck in, or which is the correct
> > > > > value. Your settings appear to make logical sense to me though, TX
> > > > > on the active side, RX on the passive side.
> > > > And as the patch sets TX and RX in the same chip I changed to follow
> > > > the documentation.
> > >
> > > Yeah I mean I suspect this is sensible, unless there is some
> > > reason the controller side also needs to have RX enabled. Perhaps
> > > for feedback or something from the passive side, but I imagine
> > > this is just a typo in the original patch.
> >
> > Ok, but the other side doesn't have both RX and TX enabled.
> > If the active side needed RX to receive information for the other 
> > side, the passive one would need TX enabled too.
> > So if a feedback is necessary, both channels on both sides would be 
> > enabled, not one channel in one side and both on the other.
> Both amps need to transmit their boost targets to the MDSYNC bus. The 
> active amp needs to receive the combined boost target from the MDSYNC 
> bus. That is why the active amp should enable both RX and TX, and the 
> passive amp only needs to enable TX. It is not simply a unidirectional 
> flow of data from one amp to the other.
>
> Sorry if the documentation has been mismatched or confusing at times. 
> It's taken me a while to gather the right understanding of how this all 
> works.
>
>
> On 2/10/23 03:19, Lucas Tanure wrote:
> > +      Shared boost allows two amplifiers to share a single boost circuit by
> > +      communicating on the MDSYNC bus. The passive amplifier does not control
> > +      the boost and receives data from the active amplifier. GPIO1 should be
>
> Not quite correct. I would suggest: "Shared boost allows two amplifiers 
> to share a single boost circuit by communicating on the MDSYNC bus. The 
> active amplifier controls the boost circuit using combined data from 
> both amplifiers."
Ok

> On 2/10/23 08:39, Lucas Tanure wrote:
> > This write here is to select the boost control source, which for the 
> > active should be "Class H tracking value". 
>
> Active should use the MDSYNC value. Otherwise it will not provide boost 
> to the passive amp when there is only audio on the passive amp's channel.
David can you confirm that both sides should use MDSYNC for boost 
control source?


> I believe there is another change needed for the Deck, to handle the 
> 'legacy' property names instead of bst-type?
I am working with valve to update their bios.

> Other than the changes needed to the reg_sequences this looks good.
>
>
> Thanks,
>
> David