Re: [PATCH 2/6] ASoC: amd: yc: Add a module parameter to influence pdm_gain

[Jaroslav Kysela]

On 27. 01. 23 17:25, Limonciello, Mario wrote:
> [AMD Official Use Only - General]
>
>
>
> > -----Original Message-----
> > From: Jaroslav Kysela <perex@xxxxxxxx>
> > Sent: Friday, January 27, 2023 10:23
> > To: Limonciello, Mario <Mario.Limonciello@xxxxxxx>; Mukunda, Vijendar
> > <Vijendar.Mukunda@xxxxxxx>; Saba Kareem, Syed
> > <Syed.SabaKareem@xxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx
> > Cc: Pananchikkal, Renjith <Renjith.Pananchikkal@xxxxxxx>; Mark Pearson
> > <mpearson@xxxxxxxxxx>; Liam Girdwood <lgirdwood@xxxxxxxxx>; Mark
> > Brown <broonie@xxxxxxxxxx>; Takashi Iwai <tiwai@xxxxxxxx>; alsa-
> > devel@xxxxxxxxxxxxxxxx
> > Subject: Re: [PATCH 2/6] ASoC: amd: yc: Add a module parameter to
> > influence pdm_gain
> >
> > On 27. 01. 23 17:01, Mario Limonciello wrote:
> > > In case of regressions for any users that the new pdm_gain value is
> > > too high and for additional debugging, introduce a module parameter
> > > that would let them configure it.
> > >
> > > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> > > ---
> > >    sound/soc/amd/yc/acp6x-pdm-dma.c | 7 ++++++-
> > >    sound/soc/amd/yc/acp6x.h         | 2 +-
> > >    2 files changed, 7 insertions(+), 2 deletions(-)
> >
> > ...
> >
> > >    	pdm_ctrl = acp6x_readl(acp_base + ACP_WOV_MISC_CTRL);
> > > -	pdm_ctrl |= ACP_WOV_MISC_CTRL_MASK;
> > > +	pdm_ctrl |= FIELD_PREP(ACP_WOV_GAIN_CONTROL, pdm_gain);
> >
> > The bits should be zeroed (AND - &) before OR to make sure that the correct
> > value is written to the register. More related patches are affected.
>
> I had consider this, but the hardware default at reset is 0x0.  Do you think it's
> still necessary for posterity?

You're using 0644 permissions for the module parameter, so the value can be 
changed by root using sysfs anytime (between SNDRV_PCM_TRIGGER calls).

						Jaroslav

--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.