Re: [Intel-gfx] [v2] drm/i915/dsi/xelpd: Add WA to program LP to HS wakeup guardband

["Kulkarni, Vandita" <vandita.kulkarni@intel.com>]

Thanks for the review. Have fixed in the latest version, will merge once CI is green.
> -----Original Message-----
> From: Nikula, Jani <jani.nikula@intel.com>
> Sent: Wednesday, August 25, 2021 7:38 PM
> To: Kulkarni, Vandita <vandita.kulkarni@intel.com>; intel-
> gfx@lists.freedesktop.org
> Cc: Kulkarni, Vandita <vandita.kulkarni@intel.com>
> Subject: Re: [v2] drm/i915/dsi/xelpd: Add WA to program LP to HS wakeup
> guardband
> 
> On Mon, 23 Aug 2021, Vandita Kulkarni <vandita.kulkarni@intel.com> wrote:
> > Wa_16012360555 SW will have to program the "LP to HS Wakeup
> Guardband"
> > field to account for the repeaters on the HS Request/Ready PPI
> > signaling between the Display engine and the DPHY.
> >
> > v2: Fix build issue.
> >
> > Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/icl_dsi.c | 25
> +++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/i915_reg.h        |  8 ++++++++
> >  2 files changed, 33 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c
> > b/drivers/gpu/drm/i915/display/icl_dsi.c
> > index 43ec7fcd3f5d..b075defb88bb 100644
> > --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> > +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> > @@ -1270,6 +1270,28 @@ static void icl_apply_kvmr_pipe_a_wa(struct
> intel_encoder *encoder,
> >  			     IGNORE_KVMR_PIPE_A,
> >  			     enable ? IGNORE_KVMR_PIPE_A : 0);  }
> > +
> > +/*
> > + * Wa_16012360555:ADLP
> 
> It should be adl-p, i.e. lower case and with a hyphen.
> 
> > + * SW will have to program the "LP to HS Wakeup Guardband"
> > + * field (bits 15:12) of register offset 0x6B0C0 (DSI0)
> > + * and 0x6B8C0 (DSI1) to a value of 4 to account for the repeaters
> > + * on the HS Request/Ready PPI signaling between
> > + * the Display engine and the DPHY.
> > + */
> 
> I think that's a bit verbose for the comment. In particular the register
> addresses and bits and values are redundant with the code.
> 
> > +static void adlp_set_lp_hs_wakeup_gb(struct intel_encoder *encoder) {
> > +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> 
> i915 variable name is preferred for all new code.
> 
> > +	struct intel_dsi *intel_dsi = enc_to_intel_dsi(encoder);
> > +	enum port port;
> > +
> > +	if (DISPLAY_VER(dev_priv) == 13) {
> > +		for_each_dsi_port(port, intel_dsi->ports)
> > +			intel_de_rmw(dev_priv, TGL_DSI_CHKN_REG(port),
> > +				     TGL_DSI_CHKN_LSHS_GB, 0x4);
> > +	}
> > +}
> > +
> >  static void gen11_dsi_enable(struct intel_atomic_state *state,
> >  			     struct intel_encoder *encoder,
> >  			     const struct intel_crtc_state *crtc_state, @@ -
> 1283,6 +1305,9
> > @@ static void gen11_dsi_enable(struct intel_atomic_state *state,
> >  	/* Wa_1409054076:icl,jsl,ehl */
> >  	icl_apply_kvmr_pipe_a_wa(encoder, crtc->pipe, true);
> >
> > +	/* Wa_16012360555: adlp */
> 
> No space after : and adl-p.
> 
> > +	adlp_set_lp_hs_wakeup_gb(encoder);
> > +
> >  	/* step6d: enable dsi transcoder */
> >  	gen11_dsi_enable_transcoder(encoder);
> >
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h
> > b/drivers/gpu/drm/i915/i915_reg.h index 72dd3a6d205d..4c90d45343d6
> > 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -11614,6 +11614,14 @@ enum skl_power_gate {
> >  						    _ICL_DSI_IO_MODECTL_1)
> >  #define  COMBO_PHY_MODE_DSI				(1 << 0)
> >
> > +/* TGL DSI Chicken register */
> > +#define _TGL_DSI_CHKN_REG_0			0x6B0C0
> > +#define _TGL_DSI_CHKN_REG_1			0x6B8C0
> > +#define TGL_DSI_CHKN_REG(port)		_MMIO_PORT(port,	\
> > +						    _TGL_DSI_CHKN_REG_0, \
> > +						    _TGL_DSI_CHKN_REG_1)
> > +#define TGL_DSI_CHKN_LSHS_GB			(0xF << 12)
> 
> Please use REG_GENMASK(15, 12)
> 
> With the issues fixed,
> 
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
> 
> 
> > +
> >  /* Display Stream Splitter Control */
> >  #define DSS_CTL1				_MMIO(0x67400)
> >  #define  SPLITTER_ENABLE			(1 << 31)
> 
> --
> Jani Nikula, Intel Open Source Graphics Center