[Intel-gfx] [PATCH 2/6] drm/i915/bdw: Add support for DRRS to switch RR

[Ramalingam C]

Hi,

On Thursday 19 February 2015 10:55 PM, Rodrigo Vivi wrote:
> On Fri, Feb 13, 2015 at 2:03 AM, Ramalingam C <ramalingam.c at intel.com> wrote:
>> From: Vandana Kannan <vandana.kannan at intel.com>
>>
>> For Broadwell, there is one instance of Transcoder MN values per transcoder.
>> For dynamic switching between multiple refreshr rates, M/N values may be
>> reprogrammed on the fly. Link N programming triggers update of all data and
>> link M & N registers and the new M/N values will be used in the next frame
>> that is output.
>>
>> V2: [By Ram]: intel_dp_set_m_n() is rewritten to accommodate
>>          gen >= 8 [Rodrigo]
>> V3: Coding style correction [Ram]
>> V4: [By Ram] intel_dp_set_m_n modifications are moved into a
>>          separate patch, retaining only DRRS related changes here [Rodrigo]
>>
>> Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
>> Signed-off-by: Pradeep Bhat <pradeep.bhat at intel.com>
>> Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_dp.c |   16 ++++++++++++++--
>>   1 file changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> index 868a07b..6ffbf57 100644
>> --- a/drivers/gpu/drm/i915/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -4793,12 +4793,24 @@ static void intel_dp_set_drrs_state(struct drm_device *dev, int refresh_rate)
>>                  return;
>>          }
>>
>> -       if (INTEL_INFO(dev)->gen > 6 && INTEL_INFO(dev)->gen < 8) {
>> +       if (INTEL_INFO(dev)->gen >= 8) {
>> +               switch (index) {
>> +               case DRRS_HIGH_RR:
>> +                       intel_dp_set_m_n(intel_crtc, M1_N1);
>> +                       break;
>> +               case DRRS_LOW_RR:
>> +                       intel_dp_set_m_n(intel_crtc, M2_N2);
>> +                       break;
>> +               case DRRS_MAX_RR:
> Why to redirect this to an error insted making MAX = HIGH?
This DRRS state is decided within kernel based on the vrefresh 
requested. Hence this can't be out of HIGH/LOW.
So this case can't occur. If it occurs I would like to report it as an 
error.
>
>> +               default:
>> +                       DRM_ERROR("Unsupported refreshrate type\n");
>> +               }
>> +       } else if (INTEL_INFO(dev)->gen > 6) {
>>                  reg = PIPECONF(intel_crtc->config->cpu_transcoder);
>>                  val = I915_READ(reg);
>> +
>>                  if (index > DRRS_HIGH_RR) {
>>                          val |= PIPECONF_EDP_RR_MODE_SWITCH;
>> -                       intel_dp_set_m_n(intel_crtc);
>>                  } else {
>>                          val &= ~PIPECONF_EDP_RR_MODE_SWITCH;
>>                  }
>> --
>> 1.7.9.5
>>
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>
>

-- 
Ram