On Wed, Feb 17, 2021 at 11:53 AM Harry Wentland <harry.wentland@xxxxxxx> wrote:
>
> On 2021-02-16 12:28 p.m., Alex Deucher wrote:
> > Commit 098214999c8f added fetching of the AUX_DPHY register
> > values from the vbios, but it also changed the default values
> > in the case when there are no values in the vbios. This causes
> > problems with displays with high refresh rates. To fix this,
> > switch back to the original default value for AUX_DPHY_TX_CONTROL.
>
> I don't see how this impacts displays with high refresh rates
> specifically. This is a change that only affects our AUX pre-charge time
> and was provided to us by the HW team. It does depend on another
> register being programmed by the VBIOS/DMCUBFW at boot.
>
> Before we revert this I would like confirmation that this is the root of
> the problem.
Any updates on this? Can we apply this in the meantime?
Thanks,
Alex
>
> Harry
>
> >
> > Fixes: 098214999c8f ("drm/amd/display: Read VBIOS Golden Settings Tbl")
> > Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1426
> > Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
> > Cc: Igor Kravchenko <Igor.Kravchenko@xxxxxxx>
> > Cc: Aric Cyr <Aric.Cyr@xxxxxxx>
> > Cc: Aurabindo Pillai <aurabindo.pillai@xxxxxxx>
> > ---
> > drivers/gpu/drm/amd/display/dc/dcn20/dcn20_link_encoder.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_link_encoder.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_link_encoder.c
> > index fa013496e26b..2f9bfaeaba8d 100644
> > --- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_link_encoder.c
> > +++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_link_encoder.c
> > @@ -341,8 +341,7 @@ void enc2_hw_init(struct link_encoder *enc)
> > } else {
> > AUX_REG_WRITE(AUX_DPHY_RX_CONTROL0, 0x103d1110);
> >
> > - AUX_REG_WRITE(AUX_DPHY_TX_CONTROL, 0x21c4d);
> > -
> > + AUX_REG_WRITE(AUX_DPHY_TX_CONTROL, 0x21c7a);
> > }
> >
> > //AUX_DPHY_TX_REF_CONTROL'AUX_TX_REF_DIV HW default is 0x32;
> >
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