Re: [PATCH v5 03/13] drm/i915/icl: Enable DDI Buffer

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 10 Jul 2018, Madhav Chauhan <madhav.chauhan@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.chauhan@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.nikula@intel.com>


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

-- 
Jani Nikula, Intel Open Source Graphics Center
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