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

[Madhav Chauhan <madhav.chauhan@intel.com>]

On 9/12/2018 12:24 AM, Jani Nikula wrote:
> 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+.

Yes. Will remove  step hardcoding  comments from patch.

Regards,
Madhav

>
> Regardless,
>
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
>
>
>> +	gen11_dsi_enable_ddi_buffer(encoder);
>>   }
>>   
>>   static void __attribute__((unused))

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