Re: [Intel-gfx] [PATCH 10/16] drm/i915: Query the vswing levels per-lane for tgl dkl phy

["Souza, Jose" <jose.souza@intel.com>]

On Wed, 2021-10-06 at 23:49 +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Prepare for per-lane drive settings by querying the desired vswing
> level per-lane.
> 
> Note that the code only does two loops, with each one writing the
> levels for two TX lanes. The register offsets also look a bit funny
> because each time through the loop we write to the exact same
> register offsets. The crucial bit is the HIP_INDEX_REG
> write that steers the same mmio window into different places.

Reviewed-by: José Roberto de Souza <jose.souza@intel.com>

> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_ddi.c | 33 ++++++++++++++----------
>  1 file changed, 19 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 1874a2ca8f3b..85247744e9dd 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -1295,9 +1295,7 @@ static void tgl_dkl_phy_set_signal_levels(struct intel_encoder *encoder,
>  {
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>  	enum tc_port tc_port = intel_port_to_tc(dev_priv, encoder->port);
> -	int level = intel_ddi_level(encoder, crtc_state, 0);
>  	const struct intel_ddi_buf_trans *trans;
> -	u32 val, dpcnt_mask, dpcnt_val;
>  	int n_entries, ln;
>  
>  	if (intel_tc_port_in_tbt_alt_mode(enc_to_dig_port(encoder)))
> @@ -1307,28 +1305,35 @@ static void tgl_dkl_phy_set_signal_levels(struct intel_encoder *encoder,
>  	if (drm_WARN_ON_ONCE(&dev_priv->drm, !trans))
>  		return;
>  
> -	dpcnt_mask = (DKL_TX_PRESHOOT_COEFF_MASK |
> -		      DKL_TX_DE_EMPAHSIS_COEFF_MASK |
> -		      DKL_TX_VSWING_CONTROL_MASK);
> -	dpcnt_val = DKL_TX_VSWING_CONTROL(trans->entries[level].dkl.vswing);
> -	dpcnt_val |= DKL_TX_DE_EMPHASIS_COEFF(trans->entries[level].dkl.de_emphasis);
> -	dpcnt_val |= DKL_TX_PRESHOOT_COEFF(trans->entries[level].dkl.preshoot);
> -
>  	for (ln = 0; ln < 2; ln++) {
> +		int level;
> +		u32 val;
> +
>  		intel_de_write(dev_priv, HIP_INDEX_REG(tc_port),
>  			       HIP_INDEX_VAL(tc_port, ln));
>  
>  		intel_de_write(dev_priv, DKL_TX_PMD_LANE_SUS(tc_port), 0);
>  
> -		/* All the registers are RMW */
> +		level = intel_ddi_level(encoder, crtc_state, 2*ln+0);
> +
>  		val = intel_de_read(dev_priv, DKL_TX_DPCNTL0(tc_port));
> -		val &= ~dpcnt_mask;
> -		val |= dpcnt_val;
> +		val &= ~(DKL_TX_PRESHOOT_COEFF_MASK |
> +			 DKL_TX_DE_EMPAHSIS_COEFF_MASK |
> +			 DKL_TX_VSWING_CONTROL_MASK);
> +		val |= DKL_TX_VSWING_CONTROL(trans->entries[level].dkl.vswing) |
> +			DKL_TX_DE_EMPHASIS_COEFF(trans->entries[level].dkl.de_emphasis) |
> +			DKL_TX_PRESHOOT_COEFF(trans->entries[level].dkl.preshoot);
>  		intel_de_write(dev_priv, DKL_TX_DPCNTL0(tc_port), val);
>  
> +		level = intel_ddi_level(encoder, crtc_state, 2*ln+1);
> +
>  		val = intel_de_read(dev_priv, DKL_TX_DPCNTL1(tc_port));
> -		val &= ~dpcnt_mask;
> -		val |= dpcnt_val;
> +		val &= ~(DKL_TX_PRESHOOT_COEFF_MASK |
> +			 DKL_TX_DE_EMPAHSIS_COEFF_MASK |
> +			 DKL_TX_VSWING_CONTROL_MASK);
> +		val |= DKL_TX_VSWING_CONTROL(trans->entries[level].dkl.vswing) |
> +			DKL_TX_DE_EMPHASIS_COEFF(trans->entries[level].dkl.de_emphasis) |
> +			DKL_TX_PRESHOOT_COEFF(trans->entries[level].dkl.preshoot);
>  		intel_de_write(dev_priv, DKL_TX_DPCNTL1(tc_port), val);
>  
>  		val = intel_de_read(dev_priv, DKL_TX_DPCNTL2(tc_port));