[Intel-gfx] [PATCH] drm/i915/mtl: Fix SSC selection for MPLLA

[Sripada, Radhakrishna]

Merged. With slight change to commit message to silence checkpatch warning. Thank you for the review.

--Radhakrishna(RK) Sripada

> -----Original Message-----
> From: Kahola, Mika <mika.kahola at intel.com>
> Sent: Friday, June 16, 2023 12:05 AM
> To: Sripada, Radhakrishna <radhakrishna.sripada at intel.com>; intel-
> gfx at lists.freedesktop.org
> Cc: Taylor, Clinton A <clinton.a.taylor at intel.com>; Almahallawy, Khaled
> <khaled.almahallawy at intel.com>; Murthy, Arun R <arun.r.murthy at intel.com>
> Subject: RE: [PATCH] drm/i915/mtl: Fix SSC selection for MPLLA
> 
> > -----Original Message-----
> > From: Sripada, Radhakrishna <radhakrishna.sripada at intel.com>
> > Sent: Friday, June 16, 2023 7:40 AM
> > To: intel-gfx at lists.freedesktop.org
> > Cc: Sripada, Radhakrishna <radhakrishna.sripada at intel.com>; Kahola, Mika
> <mika.kahola at intel.com>; Taylor, Clinton A
> > <clinton.a.taylor at intel.com>; Almahallawy, Khaled
> <khaled.almahallawy at intel.com>; Murthy, Arun R
> > <arun.r.murthy at intel.com>
> > Subject: [PATCH] drm/i915/mtl: Fix SSC selection for MPLLA
> >
> > Driver does not clear the default SSC for MPLLA. This causes link training
> failure when trying to use 10G and 20G rates. Fix the
> > behaviour and enable ssc only when we really want.
> >
> > Fixes: 237e7be0bf57 ("drm/i915/mtl: For DP2.0 10G and 20G rates use
> MPLLA")
> > Cc: Mika Kahola <mika.kahola at intel.com>
> > Cc: Clint Taylor <Clinton.A.Taylor at intel.com>
> > Cc: Khaled Almahallawy <khaled.almahallawy at intel.com>
> > Cc: Arun R Murthy <arun.r.murthy at intel.com>
> 
> Reviewed-by: Mika Kahola <mika.kahola at intel.com>
> 
> > Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_cx0_phy.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> > index f235df5646ed..1b00ef2c6185 100644
> > --- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> > +++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> > @@ -2434,7 +2434,8 @@ static void intel_program_port_clock_ctl(struct
> intel_encoder *encoder,
> >
> >  	intel_de_rmw(i915, XELPDP_PORT_CLOCK_CTL(encoder->port),
> >  		     XELPDP_LANE1_PHY_CLOCK_SELECT |
> XELPDP_FORWARD_CLOCK_UNGATE |
> > -		     XELPDP_DDI_CLOCK_SELECT_MASK |
> XELPDP_SSC_ENABLE_PLLB, val);
> > +		     XELPDP_DDI_CLOCK_SELECT_MASK |
> XELPDP_SSC_ENABLE_PLLA |
> > +		     XELPDP_SSC_ENABLE_PLLB, val);
> >  }
> >
> >  static u32 intel_cx0_get_powerdown_update(u8 lane_mask)
> > --
> > 2.34.1