diff mbox

[7/10] drm/i915: Enable eDP DRRS for CHV

Message ID 54BF97FA.7000105@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ramalingam C Jan. 21, 2015, 12:13 p.m. UTC
Hi

On Friday 16 January 2015 04:41 AM, Rodrigo Vivi wrote:
> On Fri, Jan 9, 2015 at 12:56 PM, Vandana Kannan
> <vandana.kannan@intel.com> wrote:
>> From: Durgadoss R <durgadoss.r@intel.com>
>>
>> This patch enables eDP DRRS for CHV by adding the
>> required IS_CHERRYVIEW() checks.
>> CHV uses the same register bit as VLV.
>>
>> [Vandana]: Since CHV has 2 sets of M_N registers, it will follow the same code
>> path as gen < 8. Added CHV check in dp_set_m_n()
>>
>> Signed-off-by: Durgadoss R <durgadoss.r@intel.com>
>> Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_display.c | 4 ++--
>>   drivers/gpu/drm/i915/intel_dp.c      | 2 +-
>>   2 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index 25596ca..bb44fb9 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -5810,8 +5810,8 @@ void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
>>                   * for gen < 8) and if DRRS is supported (to make sure the
>>                   * registers are not unnecessarily accessed).
>>                   */
>> -               if (m2_n2 && INTEL_INFO(dev)->gen < 8 &&
>> -                       crtc->config.has_drrs) {
>> +               if (m2_n2 && (IS_CHERRYVIEW(dev) || INTEL_INFO(dev)->gen < 8)
>> +                       && crtc->config.has_drrs) {
> This change here doesn't seem safe. As I told on previous comment I'd
> prefer changing intel_dp_set_m_n instead of re-using this intel_cpu
> one...
Though I am rewriting the intel_dp_set_m_n() that will reuse 
intel_cpu_transcoder_set_m_n() within.
But as a result, i am going to avoid the parallel usage of 
intel_cpu_transcoder_set_m_n() and intel_dp_set_m_n().
So I am afraid this check for inclusion of cherryview for m2_n2 
programming will be part of the newer code also.

Appending the RFC for the newer intel_dp_set_m_n() implementation below. 
Please review.

RFC starts here:

  drivers/gpu/drm/i915/intel_display.c |   19 ++++++++++++++++---
  drivers/gpu/drm/i915/intel_dp.c      |    6 ++----
  drivers/gpu/drm/i915/intel_drv.h     |    8 +++++++-
  3 files changed, 25 insertions(+), 8 deletions(-)

                                  struct intel_link_m_n *m2_n2);

Comments

Rodrigo Vivi Jan. 21, 2015, 3:03 p.m. UTC | #1
On Wed, 2015-01-21 at 17:43 +0530, Ramalingam C wrote:
> Hi
> 
> On Friday 16 January 2015 04:41 AM, Rodrigo Vivi wrote:
> 
> > On Fri, Jan 9, 2015 at 12:56 PM, Vandana Kannan
> > <vandana.kannan@intel.com> wrote:
> > > From: Durgadoss R <durgadoss.r@intel.com>
> > > 
> > > This patch enables eDP DRRS for CHV by adding the
> > > required IS_CHERRYVIEW() checks.
> > > CHV uses the same register bit as VLV.
> > > 
> > > [Vandana]: Since CHV has 2 sets of M_N registers, it will follow the same code
> > > path as gen < 8. Added CHV check in dp_set_m_n()
> > > 
> > > Signed-off-by: Durgadoss R <durgadoss.r@intel.com>
> > > Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_display.c | 4 ++--
> > >  drivers/gpu/drm/i915/intel_dp.c      | 2 +-
> > >  2 files changed, 3 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index 25596ca..bb44fb9 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -5810,8 +5810,8 @@ void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
> > >                  * for gen < 8) and if DRRS is supported (to make sure the
> > >                  * registers are not unnecessarily accessed).
> > >                  */
> > > -               if (m2_n2 && INTEL_INFO(dev)->gen < 8 &&
> > > -                       crtc->config.has_drrs) {
> > > +               if (m2_n2 && (IS_CHERRYVIEW(dev) || INTEL_INFO(dev)->gen < 8)
> > > +                       && crtc->config.has_drrs) {
> > This change here doesn't seem safe. As I told on previous comment I'd
> > prefer changing intel_dp_set_m_n instead of re-using this intel_cpu
> > one...
> Though I am rewriting the intel_dp_set_m_n() that will reuse
> intel_cpu_transcoder_set_m_n() within. 
> But as a result, i am going to avoid the parallel usage of
> intel_cpu_transcoder_set_m_n() and intel_dp_set_m_n().
> So I am afraid this check for inclusion of cherryview for m2_n2
> programming will be part of the newer code also. 
> 
> Appending the RFC for the newer intel_dp_set_m_n() implementation
> below. Please review.
> 
> RFC starts here:
> 
>  drivers/gpu/drm/i915/intel_display.c |   19
> ++++++++++++++++---                
>  drivers/gpu/drm/i915/intel_dp.c      |    6
> ++----                             
>  drivers/gpu/drm/i915/intel_drv.h     |    8
> +++++++-                           
>  3 files changed, 25 insertions(+), 8 deletions(-) 
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index 061a253..59cc87f
> 100644                                                   
> ---
> a/drivers/gpu/drm/i915/intel_display.c                                      
> +++
> b/drivers/gpu/drm/i915/intel_display.c                                      
> @@ -5829,13 +5829,26 @@ void intel_cpu_transcoder_set_m_n(struct
> intel_crtc *crtc,
>         }                                                                       
>  }                                                                              
>                                                                                 
> -void intel_dp_set_m_n(struct intel_crtc
> *crtc)                                 
> +void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set set
> = M1_N1)  
>  {                                                                              
> +       struct intel_link_m_n *dp_m_n,
> *dp_m2_n2;                               
> +                                                                               
> +       if (set == M1_N1)
> {                                                     
> +               dp_m_n =
> &crtc->config.dp_m_n;                                  
> +               dp_m2_n2 =
> &crtc->config.dp_m2_n2;                              
> +       } else if (set == M2_N2)
> {                                              
> +               /* Only one register programming is supported
> */                
> +               dp_m_n =
> &crtc->config.dp_m_n;                                  
> +               dp_m2_n2 =
> NULL;                                                
> +       } else
> {                                                                
> +               DRM_ERROR("Unsupported divider value
> \n");                       
> +
> return;                                                         
> +       }                                                                       
> +                                                                               
>         if
> (crtc->config.has_pch_encoder)                                       
>                 intel_pch_transcoder_set_m_n(crtc,
> &crtc->config.dp_m_n);       
> 
> else                                                                    
> -               intel_cpu_transcoder_set_m_n(crtc,
> &crtc->config.dp_m_n,        
> -
> &crtc->config.dp_m2_n2);     
> +               intel_cpu_transcoder_set_m_n(crtc, dp_m_n,
> dp_m2_n2);           
>  }                                                                              
>                                                                                 
>  static void vlv_update_pll(struct intel_crtc
> *crtc,                            
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c  
> index b315292..784b8dd
> 100644                                                   
> ---
> a/drivers/gpu/drm/i915/intel_dp.c                                           
> +++
> b/drivers/gpu/drm/i915/intel_dp.c                                           
> @@ -4817,11 +4817,10 @@ static void intel_dp_set_drrs_state(struct
> drm_device *dev, int refresh_rate)
>         if (INTEL_INFO(dev)->gen >= 8 && !IS_CHERRYVIEW(dev))
> {                 
>                 switch(index)
> {                                                 
>                 case
> DRRS_HIGH_RR:                                              
> -
> intel_dp_set_m_n(intel_crtc);                           
> +                       intel_dp_set_m_n(intel_crtc,
> M1_N1);                    
> 
> break;                                                  
>                 case
> DRRS_LOW_RR:                                               
> -
> intel_cpu_transcoder_set_m_n(intel_crtc,                
> -                                       &intel_crtc->config.dp_m2_n2,
> NULL);    
> +                       intel_dp_set_m_n(intel_crtc,
> M2_N2);                    
> 
> break;                                                  
>                 case
> DRRS_MAX_RR:                                               
> 
> default:                                                        
> @@ -4835,7 +4834,6 @@ static void intel_dp_set_drrs_state(struct
> drm_device *dev, int refresh_rate)
>                                 val |=
> PIPECONF_EDP_RR_MODE_SWITCH_VLV;         
> 
> else                                                    
>                                 val |=
> PIPECONF_EDP_RR_MODE_SWITCH;             
> -
> intel_dp_set_m_n(intel_crtc);                           
>                 } else
> {                                                        
>                         if
> (IS_VALLEYVIEW(dev))                                 
>                                 val &=
> ~PIPECONF_EDP_RR_MODE_SWITCH_VLV;        
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index 86d31f2..910e613
> 100644                                                   
> ---
> a/drivers/gpu/drm/i915/intel_drv.h                                          
> +++
> b/drivers/gpu/drm/i915/intel_drv.h                                          
> @@ -595,6 +595,12 @@ struct intel_hdmi
> {                                        
>  struct
> intel_dp_mst_encoder;                                                   
>  #define DP_MAX_DOWNSTREAM_PORTS
> 0x10                            
>                                                                                 
> +enum link_m_n_set
> {                                                            
> +       M1_N1 =
> 0,                                                              
> +
> M2_N2,                                                                  
> +
> DIVIDER_MAX                                                             

do we need this divider_max here?

> +};                                                                             
> +                                                                               
>  struct intel_dp
> {                                                              
>         uint32_t
> output_reg;                                                    
>         uint32_t
> aux_ch_ctl_reg;                                                
> @@ -983,7 +989,7 @@ void hsw_enable_pc8(struct drm_i915_private
> *dev_priv);     
>  void hsw_disable_pc8(struct drm_i915_private
> *dev_priv);                       
>  void intel_dp_get_m_n(struct intel_crtc
> *crtc,                                 
>                       struct intel_crtc_config
> *pipe_config);                   
> -void intel_dp_set_m_n(struct intel_crtc
> *crtc);                                
> +void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set set
> = M1_N1); 
>  void intel_cpu_transcoder_set_m_n(struct intel_crtc
> *crtc,                     
>                                  struct intel_link_m_n
> *m_n,                    
>                                  struct intel_link_m_n
> *m2_n2);                 
> --                                                                              
> 1.7.9.5   
> > 
> > >                         I915_WRITE(PIPE_DATA_M2(transcoder),
> > >                                         TU_SIZE(m2_n2->tu) | m2_n2->gmch_m);
> > >                         I915_WRITE(PIPE_DATA_N2(transcoder), m2_n2->gmch_n);
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > > index 3362d93..42195fe 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -4802,7 +4802,7 @@ static void intel_dp_set_drrs_state(struct drm_device *dev, int refresh_rate)
> > >                 return;
> > >         }
> > > 
> > > -       if (INTEL_INFO(dev)->gen >= 8) {
> > > +       if (INTEL_INFO(dev)->gen >= 8 && !IS_CHERRYVIEW(dev)) {
> > >                 switch(index) {
> > >                 case DRRS_HIGH_RR:
> > >                         intel_dp_set_m_n(intel_crtc);
> > > --
> > > 2.0.1
> > > 
> > > _______________________________________________
> > > Intel-gfx mailing list
> > > Intel-gfx@lists.freedesktop.org
> > > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> > 
> > 
> --Ram


But overall it is better and much more clear than previous version.
Thanks
Ramalingam C Jan. 22, 2015, 10:54 a.m. UTC | #2
On Wednesday 21 January 2015 08:33 PM, Rodrigo Vivi wrote:
> On Wed, 2015-01-21 at 17:43 +0530, Ramalingam C wrote:
>> Hi
>>
>> On Friday 16 January 2015 04:41 AM, Rodrigo Vivi wrote:
>>
>>> On Fri, Jan 9, 2015 at 12:56 PM, Vandana Kannan
>>> <vandana.kannan@intel.com> wrote:
>>>> From: Durgadoss R <durgadoss.r@intel.com>
>>>>
>>>> This patch enables eDP DRRS for CHV by adding the
>>>> required IS_CHERRYVIEW() checks.
>>>> CHV uses the same register bit as VLV.
>>>>
>>>> [Vandana]: Since CHV has 2 sets of M_N registers, it will follow the same code
>>>> path as gen < 8. Added CHV check in dp_set_m_n()
>>>>
>>>> Signed-off-by: Durgadoss R <durgadoss.r@intel.com>
>>>> Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
>>>> ---
>>>>   drivers/gpu/drm/i915/intel_display.c | 4 ++--
>>>>   drivers/gpu/drm/i915/intel_dp.c      | 2 +-
>>>>   2 files changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>>>> index 25596ca..bb44fb9 100644
>>>> --- a/drivers/gpu/drm/i915/intel_display.c
>>>> +++ b/drivers/gpu/drm/i915/intel_display.c
>>>> @@ -5810,8 +5810,8 @@ void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
>>>>                   * for gen < 8) and if DRRS is supported (to make sure the
>>>>                   * registers are not unnecessarily accessed).
>>>>                   */
>>>> -               if (m2_n2 && INTEL_INFO(dev)->gen < 8 &&
>>>> -                       crtc->config.has_drrs) {
>>>> +               if (m2_n2 && (IS_CHERRYVIEW(dev) || INTEL_INFO(dev)->gen < 8)
>>>> +                       && crtc->config.has_drrs) {
>>> This change here doesn't seem safe. As I told on previous comment I'd
>>> prefer changing intel_dp_set_m_n instead of re-using this intel_cpu
>>> one...
>> Though I am rewriting the intel_dp_set_m_n() that will reuse
>> intel_cpu_transcoder_set_m_n() within.
>> But as a result, i am going to avoid the parallel usage of
>> intel_cpu_transcoder_set_m_n() and intel_dp_set_m_n().
>> So I am afraid this check for inclusion of cherryview for m2_n2
>> programming will be part of the newer code also.
>>
>> Appending the RFC for the newer intel_dp_set_m_n() implementation
>> below. Please review.
>>
>> RFC starts here:
>>
>>   drivers/gpu/drm/i915/intel_display.c |   19
>> ++++++++++++++++---
>>   drivers/gpu/drm/i915/intel_dp.c      |    6
>> ++----
>>   drivers/gpu/drm/i915/intel_drv.h     |    8
>> +++++++-
>>   3 files changed, 25 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c
>> b/drivers/gpu/drm/i915/intel_display.c
>> index 061a253..59cc87f
>> 100644
>> ---
>> a/drivers/gpu/drm/i915/intel_display.c
>> +++
>> b/drivers/gpu/drm/i915/intel_display.c
>> @@ -5829,13 +5829,26 @@ void intel_cpu_transcoder_set_m_n(struct
>> intel_crtc *crtc,
>>          }
>>   }
>>                                                                                  
>> -void intel_dp_set_m_n(struct intel_crtc
>> *crtc)
>> +void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set set
>> = M1_N1)
>>   {
>> +       struct intel_link_m_n *dp_m_n,
>> *dp_m2_n2;
>> +
>> +       if (set == M1_N1)
>> {
>> +               dp_m_n =
>> &crtc->config.dp_m_n;
>> +               dp_m2_n2 =
>> &crtc->config.dp_m2_n2;
>> +       } else if (set == M2_N2)
>> {
>> +               /* Only one register programming is supported
>> */
>> +               dp_m_n =
>> &crtc->config.dp_m_n;
>> +               dp_m2_n2 =
>> NULL;
>> +       } else
>> {
>> +               DRM_ERROR("Unsupported divider value
>> \n");
>> +
>> return;
>> +       }
>> +
>>          if
>> (crtc->config.has_pch_encoder)
>>                  intel_pch_transcoder_set_m_n(crtc,
>> &crtc->config.dp_m_n);
>>
>> else
>> -               intel_cpu_transcoder_set_m_n(crtc,
>> &crtc->config.dp_m_n,
>> -
>> &crtc->config.dp_m2_n2);
>> +               intel_cpu_transcoder_set_m_n(crtc, dp_m_n,
>> dp_m2_n2);
>>   }
>>                                                                                  
>>   static void vlv_update_pll(struct intel_crtc
>> *crtc,
>> diff --git a/drivers/gpu/drm/i915/intel_dp.c
>> b/drivers/gpu/drm/i915/intel_dp.c
>> index b315292..784b8dd
>> 100644
>> ---
>> a/drivers/gpu/drm/i915/intel_dp.c
>> +++
>> b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -4817,11 +4817,10 @@ static void intel_dp_set_drrs_state(struct
>> drm_device *dev, int refresh_rate)
>>          if (INTEL_INFO(dev)->gen >= 8 && !IS_CHERRYVIEW(dev))
>> {
>>                  switch(index)
>> {
>>                  case
>> DRRS_HIGH_RR:
>> -
>> intel_dp_set_m_n(intel_crtc);
>> +                       intel_dp_set_m_n(intel_crtc,
>> M1_N1);
>>
>> break;
>>                  case
>> DRRS_LOW_RR:
>> -
>> intel_cpu_transcoder_set_m_n(intel_crtc,
>> -                                       &intel_crtc->config.dp_m2_n2,
>> NULL);
>> +                       intel_dp_set_m_n(intel_crtc,
>> M2_N2);
>>
>> break;
>>                  case
>> DRRS_MAX_RR:
>>
>> default:
>> @@ -4835,7 +4834,6 @@ static void intel_dp_set_drrs_state(struct
>> drm_device *dev, int refresh_rate)
>>                                  val |=
>> PIPECONF_EDP_RR_MODE_SWITCH_VLV;
>>
>> else
>>                                  val |=
>> PIPECONF_EDP_RR_MODE_SWITCH;
>> -
>> intel_dp_set_m_n(intel_crtc);
>>                  } else
>> {
>>                          if
>> (IS_VALLEYVIEW(dev))
>>                                  val &=
>> ~PIPECONF_EDP_RR_MODE_SWITCH_VLV;
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h
>> b/drivers/gpu/drm/i915/intel_drv.h
>> index 86d31f2..910e613
>> 100644
>> ---
>> a/drivers/gpu/drm/i915/intel_drv.h
>> +++
>> b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -595,6 +595,12 @@ struct intel_hdmi
>> {
>>   struct
>> intel_dp_mst_encoder;
>>   #define DP_MAX_DOWNSTREAM_PORTS
>> 0x10
>>                                                                                  
>> +enum link_m_n_set
>> {
>> +       M1_N1 =
>> 0,
>> +
>> M2_N2,
>> +
>> DIVIDER_MAX
> do we need this divider_max here?
We dont need this. Removed it in the original patch.
>
>> +};
>> +
>>   struct intel_dp
>> {
>>          uint32_t
>> output_reg;
>>          uint32_t
>> aux_ch_ctl_reg;
>> @@ -983,7 +989,7 @@ void hsw_enable_pc8(struct drm_i915_private
>> *dev_priv);
>>   void hsw_disable_pc8(struct drm_i915_private
>> *dev_priv);
>>   void intel_dp_get_m_n(struct intel_crtc
>> *crtc,
>>                        struct intel_crtc_config
>> *pipe_config);
>> -void intel_dp_set_m_n(struct intel_crtc
>> *crtc);
>> +void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set set
>> = M1_N1);
>>   void intel_cpu_transcoder_set_m_n(struct intel_crtc
>> *crtc,
>>                                   struct intel_link_m_n
>> *m_n,
>>                                   struct intel_link_m_n
>> *m2_n2);
>> --
>> 1.7.9.5
>>>>                          I915_WRITE(PIPE_DATA_M2(transcoder),
>>>>                                          TU_SIZE(m2_n2->tu) | m2_n2->gmch_m);
>>>>                          I915_WRITE(PIPE_DATA_N2(transcoder), m2_n2->gmch_n);
>>>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>>>> index 3362d93..42195fe 100644
>>>> --- a/drivers/gpu/drm/i915/intel_dp.c
>>>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>>>> @@ -4802,7 +4802,7 @@ static void intel_dp_set_drrs_state(struct drm_device *dev, int refresh_rate)
>>>>                  return;
>>>>          }
>>>>
>>>> -       if (INTEL_INFO(dev)->gen >= 8) {
>>>> +       if (INTEL_INFO(dev)->gen >= 8 && !IS_CHERRYVIEW(dev)) {
>>>>                  switch(index) {
>>>>                  case DRRS_HIGH_RR:
>>>>                          intel_dp_set_m_n(intel_crtc);
>>>> --
>>>> 2.0.1
>>>>
>>>> _______________________________________________
>>>> Intel-gfx mailing list
>>>> Intel-gfx@lists.freedesktop.org
>>>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>>
>> --Ram
>
> But overall it is better and much more clear than previous version.
I have submitted this change for the intel_dp_set_m_n() as V2 of patch 
set 5/10. So this patch [7/10] doesn't have any change.
> Thanks
>
--Ram
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_display.c 
b/drivers/gpu/drm/i915/intel_display.c
index 061a253..59cc87f 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5829,13 +5829,26 @@  void intel_cpu_transcoder_set_m_n(struct 
intel_crtc *crtc,
}
  }

-void intel_dp_set_m_n(struct intel_crtc *crtc)
+void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set set = 
M1_N1)
  {
+       struct intel_link_m_n *dp_m_n, *dp_m2_n2;
+
+       if (set == M1_N1) {
+               dp_m_n = &crtc->config.dp_m_n;
+               dp_m2_n2 = &crtc->config.dp_m2_n2;
+       } else if (set == M2_N2) {
+               /* Only one register programming is supported */
+               dp_m_n = &crtc->config.dp_m_n;
+               dp_m2_n2 = NULL;
+       } else {
+               DRM_ERROR("Unsupported divider value\n");
+ return;
+ }
+
         if (crtc->config.has_pch_encoder)
                 intel_pch_transcoder_set_m_n(crtc, &crtc->config.dp_m_n);
else
-               intel_cpu_transcoder_set_m_n(crtc, &crtc->config.dp_m_n,
- &crtc->config.dp_m2_n2);
+               intel_cpu_transcoder_set_m_n(crtc, dp_m_n, dp_m2_n2);
  }

  static void vlv_update_pll(struct intel_crtc *crtc,
diff --git a/drivers/gpu/drm/i915/intel_dp.c 
b/drivers/gpu/drm/i915/intel_dp.c
index b315292..784b8dd 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4817,11 +4817,10 @@  static void intel_dp_set_drrs_state(struct 
drm_device *dev, int refresh_rate)
         if (INTEL_INFO(dev)->gen >= 8 && !IS_CHERRYVIEW(dev)) {
                 switch(index) {
                 case DRRS_HIGH_RR:
- intel_dp_set_m_n(intel_crtc);
+                       intel_dp_set_m_n(intel_crtc, M1_N1);
break;
                 case DRRS_LOW_RR:
- intel_cpu_transcoder_set_m_n(intel_crtc,
- &intel_crtc->config.dp_m2_n2, NULL);
+                       intel_dp_set_m_n(intel_crtc, M2_N2);
break;
                 case DRRS_MAX_RR:
default:
@@ -4835,7 +4834,6 @@  static void intel_dp_set_drrs_state(struct 
drm_device *dev, int refresh_rate)
                                 val |= PIPECONF_EDP_RR_MODE_SWITCH_VLV;
else
                                 val |= PIPECONF_EDP_RR_MODE_SWITCH;
- intel_dp_set_m_n(intel_crtc);
                 } else {
                         if (IS_VALLEYVIEW(dev))
                                 val &= ~PIPECONF_EDP_RR_MODE_SWITCH_VLV;
diff --git a/drivers/gpu/drm/i915/intel_drv.h 
b/drivers/gpu/drm/i915/intel_drv.h
index 86d31f2..910e613 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -595,6 +595,12 @@  struct intel_hdmi {
  struct intel_dp_mst_encoder;
  #define DP_MAX_DOWNSTREAM_PORTS 0x10

+enum link_m_n_set {
+       M1_N1 = 0,
+ M2_N2,
+ DIVIDER_MAX
+};
+
  struct intel_dp {
         uint32_t output_reg;
         uint32_t aux_ch_ctl_reg;
@@ -983,7 +989,7 @@  void hsw_enable_pc8(struct drm_i915_private *dev_priv);
  void hsw_disable_pc8(struct drm_i915_private *dev_priv);
  void intel_dp_get_m_n(struct intel_crtc *crtc,
                       struct intel_crtc_config *pipe_config);
-void intel_dp_set_m_n(struct intel_crtc *crtc);
+void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set set = 
M1_N1);
  void intel_cpu_transcoder_set_m_n(struct intel_crtc *crtc,
                                  struct intel_link_m_n *m_n,