Re: [RESEND PATCH v2] drm/bridge: dw-hdmi-i2s: set insert_pcuv bit if hardware supports it

[Geraldo Nascimento <geraldogabriel@gmail.com>]

On Fri, Sep 13, 2024 at 06:28:34PM -0300, Geraldo Nascimento wrote:
> On Fri, Sep 13, 2024 at 10:12:39PM +0100, Hugh Cole-Baker wrote:
> > I added printk to show the value of AUD_CONF2, and found that on 6.1.23, the
> > value is 0 before the code in this patch sets the insert_pcuv bit. On 6.10.3
> > the value is 4, i.e. insert_pcuv is already set.
> > 
> > According to the RK3399 TRM, the value-after-reset of the insert_pcuv bit is 1,
> > so apparently on the 6.1.23 kernel something is clearing the bit after HW reset
> > but before this driver sets the hw_params, and this patch sets it back to the
> > correct value. On 6.10.3 the bit is not cleared, i.e. this patch is seemingly
> > no longer necessary (but is a harmless no-op).
> 
> Hi Hugh,
> 
> Thank you for your extensive testing. It seems then there's no action we
> need to take for mainline, as it's already fixed there.

Unless Neil wants to pick-up it up for Stable? Neil, although not a
regression, this is definitely a show-stopper for sound on RK3399
for older, still supported kernels. And thanks to Hugh detailed
report we now have confirmation that this happens on vanilla
RK3399 and is not a quirk of my Rock Pi N10 board or sink.

Thanks,
Geraldo Nascimento