On Wed, 2021-09-15 at 10:10 -0700, Yokoyama, Caz wrote:
> From: Caz Yokoyama <caz.yokoyama@xxxxxxxxx>
>
> Do not overwrite registers that don't need to change from default
> value to 0.
Reviewed-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
>
> bspec 49213
> Cc: Radhakrishna Sripada <radhakrishna.sripada@xxxxxxxxx>
> Cc: José Roberto de Souza <jose.souza@xxxxxxxxx>
> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Signed-off-by: Caz Yokoyama <caz.yokoyama@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_display.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index a7ca38613f89..9190a3bc28a8 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -2955,18 +2955,23 @@ static void icl_pipe_mbus_enable(struct intel_crtc *crtc, bool joined_mbus)
> {
> struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> enum pipe pipe = crtc->pipe;
> - u32 val;
> + u32 val = intel_de_read(dev_priv, PIPE_MBUS_DBOX_CTL(pipe));
>
> + val &= ~MBUS_DBOX_A_CREDIT_MASK;
> /* Wa_22010947358:adl-p */
> if (IS_ALDERLAKE_P(dev_priv))
> - val = joined_mbus ? MBUS_DBOX_A_CREDIT(6) : MBUS_DBOX_A_CREDIT(4);
> + val |= joined_mbus ? MBUS_DBOX_A_CREDIT(6) : MBUS_DBOX_A_CREDIT(4);
> else
> - val = MBUS_DBOX_A_CREDIT(2);
> + val |= MBUS_DBOX_A_CREDIT(2);
>
> - if (DISPLAY_VER(dev_priv) >= 12) {
> + if (IS_ALDERLAKE_P(dev_priv)) {
> + /* Take effect hardware default MBUS_DBOX_B_CREDIT(8) */
> + } else if (DISPLAY_VER(dev_priv) >= 12) {
> + val &= ~(MBUS_DBOX_BW_CREDIT_MASK | MBUS_DBOX_B_CREDIT_MASK);
> val |= MBUS_DBOX_BW_CREDIT(2);
> val |= MBUS_DBOX_B_CREDIT(12);
> } else {
> + val &= ~(MBUS_DBOX_BW_CREDIT_MASK | MBUS_DBOX_B_CREDIT_MASK);
> val |= MBUS_DBOX_BW_CREDIT(1);
> val |= MBUS_DBOX_B_CREDIT(8);
> }
