On Tue, 2019-10-29 at 18:24 -0700, Lucas De Marchi wrote:
> Just avoid the additional read in case DP_TP_CTL is enabled:
> read it once and save the value.
Reviewed-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_ddi.c | 33 ++++++++++++--------
> ----
> 1 file changed, 17 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c
> b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 2ce998529d08..41b9b9a6772a 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -4148,37 +4148,38 @@ static void
> intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp)
> struct drm_i915_private *dev_priv =
> to_i915(intel_dig_port->base.base.dev);
> enum port port = intel_dig_port->base.port;
> - u32 val;
> + u32 dp_tp_ctl, ddi_buf_ctl;
> bool wait = false;
>
> - if (I915_READ(intel_dp->regs.dp_tp_ctl) & DP_TP_CTL_ENABLE) {
> - val = I915_READ(DDI_BUF_CTL(port));
> - if (val & DDI_BUF_CTL_ENABLE) {
> - val &= ~DDI_BUF_CTL_ENABLE;
> - I915_WRITE(DDI_BUF_CTL(port), val);
> + dp_tp_ctl = I915_READ(intel_dp->regs.dp_tp_ctl);
> +
> + if (dp_tp_ctl & DP_TP_CTL_ENABLE) {
> + ddi_buf_ctl = I915_READ(DDI_BUF_CTL(port));
> + if (ddi_buf_ctl & DDI_BUF_CTL_ENABLE) {
> + I915_WRITE(DDI_BUF_CTL(port),
> + ddi_buf_ctl & ~DDI_BUF_CTL_ENABLE);
> wait = true;
> }
>
> - val = I915_READ(intel_dp->regs.dp_tp_ctl);
> - val &= ~(DP_TP_CTL_ENABLE | DP_TP_CTL_LINK_TRAIN_MASK);
> - val |= DP_TP_CTL_LINK_TRAIN_PAT1;
> - I915_WRITE(intel_dp->regs.dp_tp_ctl, val);
> + dp_tp_ctl &= ~(DP_TP_CTL_ENABLE |
> DP_TP_CTL_LINK_TRAIN_MASK);
> + dp_tp_ctl |= DP_TP_CTL_LINK_TRAIN_PAT1;
> + I915_WRITE(intel_dp->regs.dp_tp_ctl, dp_tp_ctl);
> POSTING_READ(intel_dp->regs.dp_tp_ctl);
>
> if (wait)
> intel_wait_ddi_buf_idle(dev_priv, port);
> }
>
> - val = DP_TP_CTL_ENABLE |
> - DP_TP_CTL_LINK_TRAIN_PAT1 | DP_TP_CTL_SCRAMBLE_DISABLE;
> + dp_tp_ctl = DP_TP_CTL_ENABLE |
> + DP_TP_CTL_LINK_TRAIN_PAT1 |
> DP_TP_CTL_SCRAMBLE_DISABLE;
> if (intel_dp->link_mst)
> - val |= DP_TP_CTL_MODE_MST;
> + dp_tp_ctl |= DP_TP_CTL_MODE_MST;
> else {
> - val |= DP_TP_CTL_MODE_SST;
> + dp_tp_ctl |= DP_TP_CTL_MODE_SST;
> if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
> - val |= DP_TP_CTL_ENHANCED_FRAME_ENABLE;
> + dp_tp_ctl |= DP_TP_CTL_ENHANCED_FRAME_ENABLE;
> }
> - I915_WRITE(intel_dp->regs.dp_tp_ctl, val);
> + I915_WRITE(intel_dp->regs.dp_tp_ctl, dp_tp_ctl);
> POSTING_READ(intel_dp->regs.dp_tp_ctl);
>
> intel_dp->DP |= DDI_BUF_CTL_ENABLE;
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