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

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

On Wed, 12 Sep 2018, Madhav Chauhan <madhav.chauhan@intel.com> wrote:
> 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.

It's unfortunate; the comments do help in review *now* but alas they
might confuse the reader tomorrow. :(

BR,
Jani.


>
> Regards,
> Madhav
>
>>
>> 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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