On Tue, 10 Jul 2018, Madhav Chauhan <madhav.chau...@intel.com> wrote:
> This patch enables DDI buffer by writing to DDI_BUF_CTL
> register and wait for DDI status to be *not idle* for a
> port.
>
> v2: Rebase
>
> Signed-off-by: Madhav Chauhan <madhav.chau...@intel.com>
> ---
>  drivers/gpu/drm/i915/icl_dsi.c | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/icl_dsi.c b/drivers/gpu/drm/i915/icl_dsi.c
> index dc16c1f..41faa19 100644
> --- a/drivers/gpu/drm/i915/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/icl_dsi.c
> @@ -251,6 +251,25 @@ static void gen11_dsi_voltage_swing_program_seq(struct 
> intel_encoder *encoder)
>       }
>  }
>  
> +static void gen11_dsi_enable_ddi_buffer(struct intel_encoder *encoder)
> +{
> +     struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> +     struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
> +     u32 tmp;
> +     enum port port;
> +
> +     for_each_dsi_port(port, intel_dsi->ports) {
> +             tmp = I915_READ(DDI_BUF_CTL(port));
> +             tmp |= DDI_BUF_CTL_ENABLE;
> +             I915_WRITE(DDI_BUF_CTL(port), tmp);
> +
> +             if (wait_for_us(!(I915_READ(DDI_BUF_CTL(port)) &
> +                               DDI_BUF_IS_IDLE),
> +                               500))

IMO a "== 0" check reads better in wait_for_us.

> +                     DRM_ERROR("DDI port:%c buffer idle\n", port_name(port));
> +     }
> +}
> +
>  static void gen11_dsi_enable_port_and_phy(struct intel_encoder *encoder)
>  {
>       /* step 4a: power up all lanes of the DDI used by DSI */
> @@ -261,6 +280,9 @@ static void gen11_dsi_enable_port_and_phy(struct 
> intel_encoder *encoder)
>  
>       /* step 4c: configure voltage swing and skew */
>       gen11_dsi_voltage_swing_program_seq(encoder);
> +
> +     /* step 4d: enable DDI buffer */

Alas, this is step 4e now, and you have a new 4d to take care of for
B0+.

Regardless,

Reviewed-by: Jani Nikula <jani.nik...@intel.com>


> +     gen11_dsi_enable_ddi_buffer(encoder);
>  }
>  
>  static void __attribute__((unused))

-- 
Jani Nikula, Intel Open Source Graphics Center
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