Re: [Intel-gfx] [PATCH 6/9] drm/i915/mtl/display: Implement DisplayPort sequences

[Imre Deak <imre.deak@intel.com>]

On Wed, Apr 12, 2023 at 03:49:22PM -0700, Radhakrishna Sripada wrote:
> [...]
> +static void mtl_disable_ddi_buf(struct intel_encoder *encoder,
> +				const struct intel_crtc_state *crtc_state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +	enum port port = encoder->port;
> +	u32 val;
> +
> +	/* 3.b Clear DDI_CTL_DE Enable to 0. */
> +	val = intel_de_read(dev_priv, DDI_BUF_CTL(port));
> +	if (val & DDI_BUF_CTL_ENABLE) {
> +		val &= ~DDI_BUF_CTL_ENABLE;
> +		intel_de_write(dev_priv, DDI_BUF_CTL(port), val);
> +
> +		/* 3.c Poll for PORT_BUF_CTL Idle Status == 1, timeout after 100us */
> +		mtl_wait_ddi_buf_idle(dev_priv, port);
> +	}
> +
> +	/* 3.d Disable D2D Link */
> +	mtl_ddi_disable_d2d_link(encoder);
> +
> +	/* 3.e Disable DP_TP_CTL */
> +	if (intel_crtc_has_dp_encoder(crtc_state)) {
> +		val = intel_de_read(dev_priv, dp_tp_ctl_reg(encoder, crtc_state));
> +		val &= ~(DP_TP_CTL_ENABLE | DP_TP_CTL_LINK_TRAIN_MASK);

Only DP_TP_CTL_ENABLE should be cleared and could use intel_de_rmw().

> +		intel_de_write(dev_priv, dp_tp_ctl_reg(encoder, crtc_state), val);
> +	}
> +}