[Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-18 Thread Manasi Navare 
If link training fails, then we need to fallback to lower
link rate first and if link training fails at RBR, then
fallback to lower lane count.
This function finds the next lower link rate/lane count
value after link training failure.

v5:
* Start the fallback at the lane count value passed not
the max lane count (Jani Nikula)
v4:
* Remove the redundant variable link_train_failed
v3:
* Remove fallback_link_rate_index variable, just obtain
that using the helper intel_dp_link_rate_index (Jani Nikula)
v2:
Squash the patch that returns the link rate index (Jani Nikula)

Acked-by: Tony Cheng 
Acked-by: Harry Wentland 
Cc: Ville Syrjala 
Cc: Jani Nikula 
Cc: Daniel Vetter 
Signed-off-by: Manasi Navare 
---
 drivers/gpu/drm/i915/intel_dp.c  | 40 
 drivers/gpu/drm/i915/intel_drv.h |  4 
 2 files changed, 44 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 90283ed..3a72014 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -288,6 +288,46 @@ static int intel_dp_common_rates(struct intel_dp *intel_dp,
   common_rates);
 }
 
+static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
+   int *common_rates, int link_rate)
+{
+   int common_len;
+   int index;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   for (index = 0; index < common_len; index++) {
+   if (link_rate == common_rates[common_len - index - 1])
+   return common_len - index - 1;
+   }
+
+   return -1;
+}
+
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count)
+{
+   int common_rates[DP_MAX_SUPPORTED_RATES] = {};
+   int common_len;
+   int link_rate_index = -1;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   link_rate_index = intel_dp_link_rate_index(intel_dp,
+  common_rates,
+  link_rate);
+   if (link_rate_index > 0) {
+   intel_dp->fallback_link_rate = common_rates[link_rate_index - 
1];
+   intel_dp->fallback_lane_count = lane_count;
+   } else if (lane_count > 1) {
+   intel_dp->fallback_link_rate = common_rates[common_len - 1];
+   intel_dp->fallback_lane_count = lane_count >> 1;
+   } else {
+   DRM_ERROR("Link Training Unsuccessful\n");
+   return -1;
+   }
+
+   return 0;
+}
+
 static enum drm_mode_status
 intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index cd132c2..e1c43a9 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -887,6 +887,8 @@ struct intel_dp {
uint32_t DP;
int link_rate;
uint8_t lane_count;
+   int fallback_link_rate;
+   uint8_t fallback_lane_count;
uint8_t sink_count;
bool link_mst;
bool has_audio;
@@ -1383,6 +1385,8 @@ bool intel_dp_init_connector(struct intel_digital_port 
*intel_dig_port,
 void intel_dp_set_link_params(struct intel_dp *intel_dp,
  int link_rate, uint8_t lane_count,
  bool link_mst);
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count);
 void intel_dp_start_link_train(struct intel_dp *intel_dp);
 void intel_dp_stop_link_train(struct intel_dp *intel_dp);
 void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
-- 
1.9.1

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Re: [Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-18 Thread Manasi Navare 
On Fri, Nov 18, 2016 at 07:39:50AM -0800, Manasi Navare wrote:
> On Fri, Nov 18, 2016 at 03:22:49PM +0200, Jani Nikula wrote:
> > On Fri, 18 Nov 2016, Manasi Navare  wrote:
> > > If link training fails, then we need to fallback to lower
> > > link rate first and if link training fails at RBR, then
> > > fallback to lower lane count.
> > > This function finds the next lower link rate/lane count
> > > value after link training failure.
> > >
> > > v4:
> > > * Remove the redundant variable link_train_failed
> > > v3:
> > > * Remove fallback_link_rate_index variable, just obtain
> > > that using the helper intel_dp_link_rate_index (Jani Nikula)
> > > v2:
> > > Squash the patch that returns the link rate index (Jani Nikula)
> > >
> > > Acked-by: Tony Cheng 
> > > Acked-by: Harry Wentland 
> > > Cc: Ville Syrjala 
> > > Cc: Jani Nikula 
> > > Cc: Daniel Vetter 
> > > Signed-off-by: Manasi Navare 
> > > ---
> > >  drivers/gpu/drm/i915/intel_dp.c  | 40 
> > > 
> > >  drivers/gpu/drm/i915/intel_drv.h |  4 
> > >  2 files changed, 44 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c 
> > > b/drivers/gpu/drm/i915/intel_dp.c
> > > index 90283ed..4fb89e1 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -288,6 +288,46 @@ static int intel_dp_common_rates(struct intel_dp 
> > > *intel_dp,
> > >  common_rates);
> > >  }
> > >  
> > > +static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
> > > + int *common_rates, int link_rate)
> > > +{
> > > + int common_len;
> > > + int index;
> > > +
> > > + common_len = intel_dp_common_rates(intel_dp, common_rates);
> > > + for (index = 0; index < common_len; index++) {
> > > + if (link_rate == common_rates[common_len - index - 1])
> > > + return common_len - index - 1;
> > > + }
> > > +
> > > + return -1;
> > > +}
> > > +
> > > +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> > > + int link_rate, uint8_t lane_count)
> > > +{
> > > + int common_rates[DP_MAX_SUPPORTED_RATES] = {};
> > > + int common_len;
> > > + int link_rate_index = -1;
> > > +
> > > + common_len = intel_dp_common_rates(intel_dp, common_rates);
> > > + link_rate_index = intel_dp_link_rate_index(intel_dp,
> > > +common_rates,
> > > +link_rate);
> > > + if (link_rate_index > 0) {
> > > + intel_dp->fallback_link_rate = common_rates[link_rate_index - 
> > > 1];
> > > + intel_dp->fallback_lane_count = 
> > > intel_dp_max_lane_count(intel_dp);
> > 
> > So you first try lower and lower link rates, until you're at the
> > lowest...
> >
> 
> Yes so first it tries to lower the link rate until it goes to the lowes i.e 
> RBR.
> All this link rate reduction happens with lane count set to maximum.
>  
> > > + } else if (lane_count > 1) {
> > > + intel_dp->fallback_link_rate = common_rates[common_len - 1];
> > > + intel_dp->fallback_lane_count = lane_count >> 1;
> > 
> > ...and then go to highest rate, double lane count, and go back back to
> > reducing link rate. Rinse and repeat.
> >
> 
> So after link rate reaches RBR, it checks if lane count is > 1 and if it is 
> then
> it jumps the link rate back to highest supported and reduces the link rate 
> from 
> 4 to 2 to 1.
>  
> > Problem is, lane_count will always be > 1, and you'll keep doubling lane
> > count without bounds if link training persistently fails, and I don't
> > think you'll reach the below else branch.
> >
> 
> So since I am reducing the lane count in each iteration, lane_count >> 1, at 
> some point
> it will go to 0 and that point it will exit with DRM_ERROR that link train 
> failed
> because at thatpoint we have exhausted trying all the link raterate and lane 
> count
> combinations. 
> I am never doubling the link rate for it to reach out of bounds, infact I am 
> reducing
> the link rate to half each time (right shifting lane count) so at some point 
> lane count will
> fall to less than 0 when it will fall into the last else part.
> 
> Regards
> Manasi
> 
>

The only problem i found is that I am setting lane count to max lane count 
which is wrong
in each iteration it should be set to lane count being passed in and it should 
start from that value and fallback.
So for Ex: If the first modeset is trying to train link at 2.7 and 4 lanes and 
link training fails,
Iteration 1 : 1.62 and 4 if this fails
Iteration 2: max link rate 5.4 and 2 (reduced lane count is halved)
Iteration 3: 2.7 and 2
Iteration 4: 1.62 and 2
Iteration 5: 5.4 and 1
iteration 6: 2.7 and 1
Iteration 7: 1.62 and 1
If this fails then

Re: [Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-18 Thread Manasi Navare 
On Fri, Nov 18, 2016 at 03:22:49PM +0200, Jani Nikula wrote:
> On Fri, 18 Nov 2016, Manasi Navare  wrote:
> > If link training fails, then we need to fallback to lower
> > link rate first and if link training fails at RBR, then
> > fallback to lower lane count.
> > This function finds the next lower link rate/lane count
> > value after link training failure.
> >
> > v4:
> > * Remove the redundant variable link_train_failed
> > v3:
> > * Remove fallback_link_rate_index variable, just obtain
> > that using the helper intel_dp_link_rate_index (Jani Nikula)
> > v2:
> > Squash the patch that returns the link rate index (Jani Nikula)
> >
> > Acked-by: Tony Cheng 
> > Acked-by: Harry Wentland 
> > Cc: Ville Syrjala 
> > Cc: Jani Nikula 
> > Cc: Daniel Vetter 
> > Signed-off-by: Manasi Navare 
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c  | 40 
> > 
> >  drivers/gpu/drm/i915/intel_drv.h |  4 
> >  2 files changed, 44 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c 
> > b/drivers/gpu/drm/i915/intel_dp.c
> > index 90283ed..4fb89e1 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -288,6 +288,46 @@ static int intel_dp_common_rates(struct intel_dp 
> > *intel_dp,
> >common_rates);
> >  }
> >  
> > +static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
> > +   int *common_rates, int link_rate)
> > +{
> > +   int common_len;
> > +   int index;
> > +
> > +   common_len = intel_dp_common_rates(intel_dp, common_rates);
> > +   for (index = 0; index < common_len; index++) {
> > +   if (link_rate == common_rates[common_len - index - 1])
> > +   return common_len - index - 1;
> > +   }
> > +
> > +   return -1;
> > +}
> > +
> > +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> > +   int link_rate, uint8_t lane_count)
> > +{
> > +   int common_rates[DP_MAX_SUPPORTED_RATES] = {};
> > +   int common_len;
> > +   int link_rate_index = -1;
> > +
> > +   common_len = intel_dp_common_rates(intel_dp, common_rates);
> > +   link_rate_index = intel_dp_link_rate_index(intel_dp,
> > +  common_rates,
> > +  link_rate);
> > +   if (link_rate_index > 0) {
> > +   intel_dp->fallback_link_rate = common_rates[link_rate_index - 
> > 1];
> > +   intel_dp->fallback_lane_count = 
> > intel_dp_max_lane_count(intel_dp);
> 
> So you first try lower and lower link rates, until you're at the
> lowest...
>

Yes so first it tries to lower the link rate until it goes to the lowes i.e RBR.
All this link rate reduction happens with lane count set to maximum.
 
> > +   } else if (lane_count > 1) {
> > +   intel_dp->fallback_link_rate = common_rates[common_len - 1];
> > +   intel_dp->fallback_lane_count = lane_count >> 1;
> 
> ...and then go to highest rate, double lane count, and go back back to
> reducing link rate. Rinse and repeat.
>

So after link rate reaches RBR, it checks if lane count is > 1 and if it is then
it jumps the link rate back to highest supported and reduces the link rate from 
4 to 2 to 1.
 
> Problem is, lane_count will always be > 1, and you'll keep doubling lane
> count without bounds if link training persistently fails, and I don't
> think you'll reach the below else branch.
>

So since I am reducing the lane count in each iteration, lane_count >> 1, at 
some point
it will go to 0 and that point it will exit with DRM_ERROR that link train 
failed
because at thatpoint we have exhausted trying all the link raterate and lane 
count
combinations. 
I am never doubling the link rate for it to reach out of bounds, infact I am 
reducing
the link rate to half each time (right shifting lane count) so at some point 
lane count will
fall to less than 0 when it will fall into the last else part.

Regards
Manasi

 
> I regret that I haven't caught all of these issues all at once; it is in
> part testament to the fact that the state machine here is not easy to
> follow.
> 
> BR,
> Jani.
>
 
> > +   } else {
> > +   DRM_ERROR("Link Training Unsuccessful\n");
> > +   return -1;
> > +   }
> > +
> > +   return 0;
> > +}
> > +
> >  static enum drm_mode_status
> >  intel_dp_mode_valid(struct drm_connector *connector,
> > struct drm_display_mode *mode)
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> > b/drivers/gpu/drm/i915/intel_drv.h
> > index cd132c2..e1c43a9 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -887,6 +887,8 @@ struct intel_dp {
> > uint32_t DP;
> > int link_rate;
> > uint8_t lane_count;
>

Re: [Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-18 Thread Jani Nikula 
On Fri, 18 Nov 2016, Manasi Navare  wrote:
> If link training fails, then we need to fallback to lower
> link rate first and if link training fails at RBR, then
> fallback to lower lane count.
> This function finds the next lower link rate/lane count
> value after link training failure.
>
> v4:
> * Remove the redundant variable link_train_failed
> v3:
> * Remove fallback_link_rate_index variable, just obtain
> that using the helper intel_dp_link_rate_index (Jani Nikula)
> v2:
> Squash the patch that returns the link rate index (Jani Nikula)
>
> Acked-by: Tony Cheng 
> Acked-by: Harry Wentland 
> Cc: Ville Syrjala 
> Cc: Jani Nikula 
> Cc: Daniel Vetter 
> Signed-off-by: Manasi Navare 
> ---
>  drivers/gpu/drm/i915/intel_dp.c  | 40 
> 
>  drivers/gpu/drm/i915/intel_drv.h |  4 
>  2 files changed, 44 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 90283ed..4fb89e1 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -288,6 +288,46 @@ static int intel_dp_common_rates(struct intel_dp 
> *intel_dp,
>  common_rates);
>  }
>  
> +static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
> + int *common_rates, int link_rate)
> +{
> + int common_len;
> + int index;
> +
> + common_len = intel_dp_common_rates(intel_dp, common_rates);
> + for (index = 0; index < common_len; index++) {
> + if (link_rate == common_rates[common_len - index - 1])
> + return common_len - index - 1;
> + }
> +
> + return -1;
> +}
> +
> +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> + int link_rate, uint8_t lane_count)
> +{
> + int common_rates[DP_MAX_SUPPORTED_RATES] = {};
> + int common_len;
> + int link_rate_index = -1;
> +
> + common_len = intel_dp_common_rates(intel_dp, common_rates);
> + link_rate_index = intel_dp_link_rate_index(intel_dp,
> +common_rates,
> +link_rate);
> + if (link_rate_index > 0) {
> + intel_dp->fallback_link_rate = common_rates[link_rate_index - 
> 1];
> + intel_dp->fallback_lane_count = 
> intel_dp_max_lane_count(intel_dp);

So you first try lower and lower link rates, until you're at the
lowest...

> + } else if (lane_count > 1) {
> + intel_dp->fallback_link_rate = common_rates[common_len - 1];
> + intel_dp->fallback_lane_count = lane_count >> 1;

...and then go to highest rate, double lane count, and go back back to
reducing link rate. Rinse and repeat.

Problem is, lane_count will always be > 1, and you'll keep doubling lane
count without bounds if link training persistently fails, and I don't
think you'll reach the below else branch.

I regret that I haven't caught all of these issues all at once; it is in
part testament to the fact that the state machine here is not easy to
follow.

BR,
Jani.

> + } else {
> + DRM_ERROR("Link Training Unsuccessful\n");
> + return -1;
> + }
> +
> + return 0;
> +}
> +
>  static enum drm_mode_status
>  intel_dp_mode_valid(struct drm_connector *connector,
>   struct drm_display_mode *mode)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> b/drivers/gpu/drm/i915/intel_drv.h
> index cd132c2..e1c43a9 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -887,6 +887,8 @@ struct intel_dp {
>   uint32_t DP;
>   int link_rate;
>   uint8_t lane_count;
> + int fallback_link_rate;
> + uint8_t fallback_lane_count;
>   uint8_t sink_count;
>   bool link_mst;
>   bool has_audio;
> @@ -1383,6 +1385,8 @@ bool intel_dp_init_connector(struct intel_digital_port 
> *intel_dig_port,
>  void intel_dp_set_link_params(struct intel_dp *intel_dp,
> int link_rate, uint8_t lane_count,
> bool link_mst);
> +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> + int link_rate, uint8_t lane_count);
>  void intel_dp_start_link_train(struct intel_dp *intel_dp);
>  void intel_dp_stop_link_train(struct intel_dp *intel_dp);
>  void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);

-- 
Jani Nikula, Intel Open Source Technology Center
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[Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-17 Thread Manasi Navare 
If link training fails, then we need to fallback to lower
link rate first and if link training fails at RBR, then
fallback to lower lane count.
This function finds the next lower link rate/lane count
value after link training failure.

v4:
* Remove the redundant variable link_train_failed
v3:
* Remove fallback_link_rate_index variable, just obtain
that using the helper intel_dp_link_rate_index (Jani Nikula)
v2:
Squash the patch that returns the link rate index (Jani Nikula)

Acked-by: Tony Cheng 
Acked-by: Harry Wentland 
Cc: Ville Syrjala 
Cc: Jani Nikula 
Cc: Daniel Vetter 
Signed-off-by: Manasi Navare 
---
 drivers/gpu/drm/i915/intel_dp.c  | 40 
 drivers/gpu/drm/i915/intel_drv.h |  4 
 2 files changed, 44 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 90283ed..4fb89e1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -288,6 +288,46 @@ static int intel_dp_common_rates(struct intel_dp *intel_dp,
   common_rates);
 }
 
+static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
+   int *common_rates, int link_rate)
+{
+   int common_len;
+   int index;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   for (index = 0; index < common_len; index++) {
+   if (link_rate == common_rates[common_len - index - 1])
+   return common_len - index - 1;
+   }
+
+   return -1;
+}
+
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count)
+{
+   int common_rates[DP_MAX_SUPPORTED_RATES] = {};
+   int common_len;
+   int link_rate_index = -1;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   link_rate_index = intel_dp_link_rate_index(intel_dp,
+  common_rates,
+  link_rate);
+   if (link_rate_index > 0) {
+   intel_dp->fallback_link_rate = common_rates[link_rate_index - 
1];
+   intel_dp->fallback_lane_count = 
intel_dp_max_lane_count(intel_dp);
+   } else if (lane_count > 1) {
+   intel_dp->fallback_link_rate = common_rates[common_len - 1];
+   intel_dp->fallback_lane_count = lane_count >> 1;
+   } else {
+   DRM_ERROR("Link Training Unsuccessful\n");
+   return -1;
+   }
+
+   return 0;
+}
+
 static enum drm_mode_status
 intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index cd132c2..e1c43a9 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -887,6 +887,8 @@ struct intel_dp {
uint32_t DP;
int link_rate;
uint8_t lane_count;
+   int fallback_link_rate;
+   uint8_t fallback_lane_count;
uint8_t sink_count;
bool link_mst;
bool has_audio;
@@ -1383,6 +1385,8 @@ bool intel_dp_init_connector(struct intel_digital_port 
*intel_dig_port,
 void intel_dp_set_link_params(struct intel_dp *intel_dp,
  int link_rate, uint8_t lane_count,
  bool link_mst);
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count);
 void intel_dp_start_link_train(struct intel_dp *intel_dp);
 void intel_dp_stop_link_train(struct intel_dp *intel_dp);
 void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
-- 
1.9.1

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[Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-17 Thread Manasi Navare 
If link training fails, then we need to fallback to lower
link rate first and if link training fails at RBR, then
fallback to lower lane count.
This function finds the next lower link rate/lane count
value after link training failure.

v3:
* Remove fallback_link_rate_index variable, just obtain
that using the helper intel_dp_link_rate_index (Jani Nikula)
v2:
Squash the patch that returns the link rate index (Jani Nikula)

Acked-by: Tony Cheng 
Acked-by: Harry Wentland 
Cc: Ville Syrjala 
Cc: Jani Nikula 
Cc: Daniel Vetter 
Signed-off-by: Manasi Navare 
---
 drivers/gpu/drm/i915/intel_dp.c  | 40 
 drivers/gpu/drm/i915/intel_drv.h |  5 +
 2 files changed, 45 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 90283ed..4fb89e1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -288,6 +288,46 @@ static int intel_dp_common_rates(struct intel_dp *intel_dp,
   common_rates);
 }
 
+static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
+   int *common_rates, int link_rate)
+{
+   int common_len;
+   int index;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   for (index = 0; index < common_len; index++) {
+   if (link_rate == common_rates[common_len - index - 1])
+   return common_len - index - 1;
+   }
+
+   return -1;
+}
+
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count)
+{
+   int common_rates[DP_MAX_SUPPORTED_RATES] = {};
+   int common_len;
+   int link_rate_index = -1;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   link_rate_index = intel_dp_link_rate_index(intel_dp,
+  common_rates,
+  link_rate);
+   if (link_rate_index > 0) {
+   intel_dp->fallback_link_rate = common_rates[link_rate_index - 
1];
+   intel_dp->fallback_lane_count = 
intel_dp_max_lane_count(intel_dp);
+   } else if (lane_count > 1) {
+   intel_dp->fallback_link_rate = common_rates[common_len - 1];
+   intel_dp->fallback_lane_count = lane_count >> 1;
+   } else {
+   DRM_ERROR("Link Training Unsuccessful\n");
+   return -1;
+   }
+
+   return 0;
+}
+
 static enum drm_mode_status
 intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index cd132c2..3f6b4c9 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -887,6 +887,9 @@ struct intel_dp {
uint32_t DP;
int link_rate;
uint8_t lane_count;
+   int fallback_link_rate;
+   uint8_t fallback_lane_count;
+   bool link_train_failed;
uint8_t sink_count;
bool link_mst;
bool has_audio;
@@ -1383,6 +1386,8 @@ bool intel_dp_init_connector(struct intel_digital_port 
*intel_dig_port,
 void intel_dp_set_link_params(struct intel_dp *intel_dp,
  int link_rate, uint8_t lane_count,
  bool link_mst);
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count);
 void intel_dp_start_link_train(struct intel_dp *intel_dp);
 void intel_dp_stop_link_train(struct intel_dp *intel_dp);
 void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
-- 
1.9.1

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Re: [Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-17 Thread Manasi Navare 
On Thu, Nov 17, 2016 at 02:58:46PM +0200, Jani Nikula wrote:
> On Tue, 15 Nov 2016, Manasi Navare  wrote:
> > If link training fails, then we need to fallback to lower
> > link rate first and if link training fails at RBR, then
> > fallback to lower lane count.
> > This function finds the next lower link rate/lane count
> > value after link training failure.
> >
> > v2:
> > Squash the patch that returns the link rate index (Jani Nikula)
> >
> > Acked-by: Tony Cheng 
> > Acked-by: Harry Wentland 
> > Cc: Ville Syrjala 
> > Cc: Jani Nikula 
> > Cc: Daniel Vetter 
> > Signed-off-by: Manasi Navare 
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c  | 42 
> > 
> >  drivers/gpu/drm/i915/intel_drv.h |  6 ++
> >  2 files changed, 48 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c 
> > b/drivers/gpu/drm/i915/intel_dp.c
> > index a1b0181..e87b451 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -288,6 +288,48 @@ static int intel_dp_common_rates(struct intel_dp 
> > *intel_dp,
> >common_rates);
> >  }
> >  
> > +static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
> > +   int *common_rates, int link_rate)
> > +{
> > +   int common_len;
> > +   int index;
> > +
> > +   common_len = intel_dp_common_rates(intel_dp, common_rates);
> > +   for (index = 0; index < common_len; index++) {
> > +   if (link_rate == common_rates[common_len - index - 1])
> > +   return common_len - index - 1;
> > +   }
> > +
> > +   return -1;
> > +}
> > +
> > +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> > +   int link_rate, uint8_t lane_count)
> > +{
> > +   int common_rates[DP_MAX_SUPPORTED_RATES] = {};
> > +   int common_len;
> > +   int link_rate_index = -1;
> > +
> > +   common_len = intel_dp_common_rates(intel_dp, common_rates);
> > +   link_rate_index = intel_dp_link_rate_index(intel_dp,
> > +  common_rates,
> > +  link_rate);
> > +   if (link_rate_index > 0) {
> > +   intel_dp->fallback_link_rate_index = link_rate_index - 1;
> > +   intel_dp->fallback_link_rate = 
> > common_rates[intel_dp->fallback_link_rate_index];
> 
> fallback_link_rate_index and fallback_link_rate are two ways to express
> the same thing, and you can derive one from the other. When you have
> two, you run the risk of having them out of sync. I thought I'd
> mentioned this in earlier review.
> 
> Please do not store fallback_link_rate_index in intel_dp. Only store
> fallback_link_rate. You can use your intel_dp_link_rate_index() function
> when you need to convert rate to index.
> 
> Moreover, resetting the state becomes more clear when all can be set to
> 0.
> 
> BR,
> Jani.
>

Thanks Jani.
From the previous feedback, I removed the redundant link_train_failed variable
stored in intel_dp, but retained the link_rate_index. I will look at this and 
see
if this can be optimized. 

Manasi

 
> > +   intel_dp->fallback_lane_count = 
> > intel_dp_max_lane_count(intel_dp);
> > +   } else if (lane_count > 1) {
> > +   intel_dp->fallback_link_rate_index = common_len - 1;
> > +   intel_dp->fallback_link_rate = 
> > common_rates[intel_dp->fallback_link_rate_index];
> > +   intel_dp->fallback_lane_count = lane_count >> 1;
> > +   } else {
> > +   DRM_ERROR("Link Training Unsuccessful\n");
> > +   return -1;
> > +   }
> > +
> > +   return 0;
> > +}
> > +
> >  static enum drm_mode_status
> >  intel_dp_mode_valid(struct drm_connector *connector,
> > struct drm_display_mode *mode)
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> > b/drivers/gpu/drm/i915/intel_drv.h
> > index 75252ec..55ceb44 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -887,6 +887,10 @@ struct intel_dp {
> > uint32_t DP;
> > int link_rate;
> > uint8_t lane_count;
> > +   int fallback_link_rate;
> > +   uint8_t fallback_lane_count;
> > +   int fallback_link_rate_index;
> > +   bool link_train_failed;
> > uint8_t sink_count;
> > bool link_mst;
> > bool has_audio;
> > @@ -1383,6 +1387,8 @@ bool intel_dp_init_connector(struct 
> > intel_digital_port *intel_dig_port,
> >  void intel_dp_set_link_params(struct intel_dp *intel_dp,
> >   int link_rate, uint8_t lane_count,
> >   bool link_mst);
> > +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> > +   int link_rate, uint8_t lane_count);
> >  void intel_dp_start_link_train(struct

Re: [Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-17 Thread Jani Nikula 
On Tue, 15 Nov 2016, Manasi Navare  wrote:
> If link training fails, then we need to fallback to lower
> link rate first and if link training fails at RBR, then
> fallback to lower lane count.
> This function finds the next lower link rate/lane count
> value after link training failure.
>
> v2:
> Squash the patch that returns the link rate index (Jani Nikula)
>
> Acked-by: Tony Cheng 
> Acked-by: Harry Wentland 
> Cc: Ville Syrjala 
> Cc: Jani Nikula 
> Cc: Daniel Vetter 
> Signed-off-by: Manasi Navare 
> ---
>  drivers/gpu/drm/i915/intel_dp.c  | 42 
> 
>  drivers/gpu/drm/i915/intel_drv.h |  6 ++
>  2 files changed, 48 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index a1b0181..e87b451 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -288,6 +288,48 @@ static int intel_dp_common_rates(struct intel_dp 
> *intel_dp,
>  common_rates);
>  }
>  
> +static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
> + int *common_rates, int link_rate)
> +{
> + int common_len;
> + int index;
> +
> + common_len = intel_dp_common_rates(intel_dp, common_rates);
> + for (index = 0; index < common_len; index++) {
> + if (link_rate == common_rates[common_len - index - 1])
> + return common_len - index - 1;
> + }
> +
> + return -1;
> +}
> +
> +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> + int link_rate, uint8_t lane_count)
> +{
> + int common_rates[DP_MAX_SUPPORTED_RATES] = {};
> + int common_len;
> + int link_rate_index = -1;
> +
> + common_len = intel_dp_common_rates(intel_dp, common_rates);
> + link_rate_index = intel_dp_link_rate_index(intel_dp,
> +common_rates,
> +link_rate);
> + if (link_rate_index > 0) {
> + intel_dp->fallback_link_rate_index = link_rate_index - 1;
> + intel_dp->fallback_link_rate = 
> common_rates[intel_dp->fallback_link_rate_index];

fallback_link_rate_index and fallback_link_rate are two ways to express
the same thing, and you can derive one from the other. When you have
two, you run the risk of having them out of sync. I thought I'd
mentioned this in earlier review.

Please do not store fallback_link_rate_index in intel_dp. Only store
fallback_link_rate. You can use your intel_dp_link_rate_index() function
when you need to convert rate to index.

Moreover, resetting the state becomes more clear when all can be set to
0.

BR,
Jani.

> + intel_dp->fallback_lane_count = 
> intel_dp_max_lane_count(intel_dp);
> + } else if (lane_count > 1) {
> + intel_dp->fallback_link_rate_index = common_len - 1;
> + intel_dp->fallback_link_rate = 
> common_rates[intel_dp->fallback_link_rate_index];
> + intel_dp->fallback_lane_count = lane_count >> 1;
> + } else {
> + DRM_ERROR("Link Training Unsuccessful\n");
> + return -1;
> + }
> +
> + return 0;
> +}
> +
>  static enum drm_mode_status
>  intel_dp_mode_valid(struct drm_connector *connector,
>   struct drm_display_mode *mode)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> b/drivers/gpu/drm/i915/intel_drv.h
> index 75252ec..55ceb44 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -887,6 +887,10 @@ struct intel_dp {
>   uint32_t DP;
>   int link_rate;
>   uint8_t lane_count;
> + int fallback_link_rate;
> + uint8_t fallback_lane_count;
> + int fallback_link_rate_index;
> + bool link_train_failed;
>   uint8_t sink_count;
>   bool link_mst;
>   bool has_audio;
> @@ -1383,6 +1387,8 @@ bool intel_dp_init_connector(struct intel_digital_port 
> *intel_dig_port,
>  void intel_dp_set_link_params(struct intel_dp *intel_dp,
> int link_rate, uint8_t lane_count,
> bool link_mst);
> +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> + int link_rate, uint8_t lane_count);
>  void intel_dp_start_link_train(struct intel_dp *intel_dp);
>  void intel_dp_stop_link_train(struct intel_dp *intel_dp);
>  void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);

-- 
Jani Nikula, Intel Open Source Technology Center
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Re: [Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-16 Thread Manasi Navare 
Jani/Ville , could you please review this patch?
Jani, you had mentioned it looks good and we were only waiting for
ACKs from DRM, so now from the DRM point of view all these patches
are ACKed and it looks good. 
But I need r-b for these two i915 specific patches to get them merged.

Regards
Manasi

On Mon, Nov 14, 2016 at 07:13:22PM -0800, Manasi Navare wrote:
> If link training fails, then we need to fallback to lower
> link rate first and if link training fails at RBR, then
> fallback to lower lane count.
> This function finds the next lower link rate/lane count
> value after link training failure.
> 
> v2:
> Squash the patch that returns the link rate index (Jani Nikula)
> 
> Acked-by: Tony Cheng 
> Acked-by: Harry Wentland 
> Cc: Ville Syrjala 
> Cc: Jani Nikula 
> Cc: Daniel Vetter 
> Signed-off-by: Manasi Navare 
> ---
>  drivers/gpu/drm/i915/intel_dp.c  | 42 
> 
>  drivers/gpu/drm/i915/intel_drv.h |  6 ++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index a1b0181..e87b451 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -288,6 +288,48 @@ static int intel_dp_common_rates(struct intel_dp 
> *intel_dp,
>  common_rates);
>  }
>  
> +static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
> + int *common_rates, int link_rate)
> +{
> + int common_len;
> + int index;
> +
> + common_len = intel_dp_common_rates(intel_dp, common_rates);
> + for (index = 0; index < common_len; index++) {
> + if (link_rate == common_rates[common_len - index - 1])
> + return common_len - index - 1;
> + }
> +
> + return -1;
> +}
> +
> +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> + int link_rate, uint8_t lane_count)
> +{
> + int common_rates[DP_MAX_SUPPORTED_RATES] = {};
> + int common_len;
> + int link_rate_index = -1;
> +
> + common_len = intel_dp_common_rates(intel_dp, common_rates);
> + link_rate_index = intel_dp_link_rate_index(intel_dp,
> +common_rates,
> +link_rate);
> + if (link_rate_index > 0) {
> + intel_dp->fallback_link_rate_index = link_rate_index - 1;
> + intel_dp->fallback_link_rate = 
> common_rates[intel_dp->fallback_link_rate_index];
> + intel_dp->fallback_lane_count = 
> intel_dp_max_lane_count(intel_dp);
> + } else if (lane_count > 1) {
> + intel_dp->fallback_link_rate_index = common_len - 1;
> + intel_dp->fallback_link_rate = 
> common_rates[intel_dp->fallback_link_rate_index];
> + intel_dp->fallback_lane_count = lane_count >> 1;
> + } else {
> + DRM_ERROR("Link Training Unsuccessful\n");
> + return -1;
> + }
> +
> + return 0;
> +}
> +
>  static enum drm_mode_status
>  intel_dp_mode_valid(struct drm_connector *connector,
>   struct drm_display_mode *mode)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> b/drivers/gpu/drm/i915/intel_drv.h
> index 75252ec..55ceb44 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -887,6 +887,10 @@ struct intel_dp {
>   uint32_t DP;
>   int link_rate;
>   uint8_t lane_count;
> + int fallback_link_rate;
> + uint8_t fallback_lane_count;
> + int fallback_link_rate_index;
> + bool link_train_failed;
>   uint8_t sink_count;
>   bool link_mst;
>   bool has_audio;
> @@ -1383,6 +1387,8 @@ bool intel_dp_init_connector(struct intel_digital_port 
> *intel_dig_port,
>  void intel_dp_set_link_params(struct intel_dp *intel_dp,
> int link_rate, uint8_t lane_count,
> bool link_mst);
> +int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> + int link_rate, uint8_t lane_count);
>  void intel_dp_start_link_train(struct intel_dp *intel_dp);
>  void intel_dp_stop_link_train(struct intel_dp *intel_dp);
>  void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
> -- 
> 1.9.1
> 
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[Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-14 Thread Manasi Navare 
If link training fails, then we need to fallback to lower
link rate first and if link training fails at RBR, then
fallback to lower lane count.
This function finds the next lower link rate/lane count
value after link training failure.

v2:
Squash the patch that returns the link rate index (Jani Nikula)

Acked-by: Tony Cheng 
Acked-by: Harry Wentland 
Cc: Ville Syrjala 
Cc: Jani Nikula 
Cc: Daniel Vetter 
Signed-off-by: Manasi Navare 
---
 drivers/gpu/drm/i915/intel_dp.c  | 42 
 drivers/gpu/drm/i915/intel_drv.h |  6 ++
 2 files changed, 48 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index a1b0181..e87b451 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -288,6 +288,48 @@ static int intel_dp_common_rates(struct intel_dp *intel_dp,
   common_rates);
 }
 
+static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
+   int *common_rates, int link_rate)
+{
+   int common_len;
+   int index;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   for (index = 0; index < common_len; index++) {
+   if (link_rate == common_rates[common_len - index - 1])
+   return common_len - index - 1;
+   }
+
+   return -1;
+}
+
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count)
+{
+   int common_rates[DP_MAX_SUPPORTED_RATES] = {};
+   int common_len;
+   int link_rate_index = -1;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   link_rate_index = intel_dp_link_rate_index(intel_dp,
+  common_rates,
+  link_rate);
+   if (link_rate_index > 0) {
+   intel_dp->fallback_link_rate_index = link_rate_index - 1;
+   intel_dp->fallback_link_rate = 
common_rates[intel_dp->fallback_link_rate_index];
+   intel_dp->fallback_lane_count = 
intel_dp_max_lane_count(intel_dp);
+   } else if (lane_count > 1) {
+   intel_dp->fallback_link_rate_index = common_len - 1;
+   intel_dp->fallback_link_rate = 
common_rates[intel_dp->fallback_link_rate_index];
+   intel_dp->fallback_lane_count = lane_count >> 1;
+   } else {
+   DRM_ERROR("Link Training Unsuccessful\n");
+   return -1;
+   }
+
+   return 0;
+}
+
 static enum drm_mode_status
 intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 75252ec..55ceb44 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -887,6 +887,10 @@ struct intel_dp {
uint32_t DP;
int link_rate;
uint8_t lane_count;
+   int fallback_link_rate;
+   uint8_t fallback_lane_count;
+   int fallback_link_rate_index;
+   bool link_train_failed;
uint8_t sink_count;
bool link_mst;
bool has_audio;
@@ -1383,6 +1387,8 @@ bool intel_dp_init_connector(struct intel_digital_port 
*intel_dig_port,
 void intel_dp_set_link_params(struct intel_dp *intel_dp,
  int link_rate, uint8_t lane_count,
  bool link_mst);
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count);
 void intel_dp_start_link_train(struct intel_dp *intel_dp);
 void intel_dp_stop_link_train(struct intel_dp *intel_dp);
 void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
-- 
1.9.1

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[Intel-gfx] [PATCH 4/5] drm/i915: Find fallback link rate/lane count

2016-11-09 Thread Manasi Navare 
If link training fails, then we need to fallback to lower
link rate first and if link training fails at RBR, then
fallback to lower lane count.
This function finds the next lower link rate/lane count
value after link training failure.

v2:
Squash the patch that returns the link rate index (Jani Nikula)

Cc: Ville Syrjala 
Cc: Jani Nikula 
Cc: Daniel Vetter 
Signed-off-by: Manasi Navare 
---
 drivers/gpu/drm/i915/intel_dp.c  | 42 
 drivers/gpu/drm/i915/intel_drv.h |  6 ++
 2 files changed, 48 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 1f1760f..9694857 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -288,6 +288,48 @@ static int intel_dp_common_rates(struct intel_dp *intel_dp,
   common_rates);
 }
 
+static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
+   int *common_rates, int link_rate)
+{
+   int common_len;
+   int index;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   for (index = 0; index < common_len; index++) {
+   if (link_rate == common_rates[common_len - index - 1])
+   return common_len - index - 1;
+   }
+
+   return -1;
+}
+
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count)
+{
+   int common_rates[DP_MAX_SUPPORTED_RATES] = {};
+   int common_len;
+   int link_rate_index = -1;
+
+   common_len = intel_dp_common_rates(intel_dp, common_rates);
+   link_rate_index = intel_dp_link_rate_index(intel_dp,
+  common_rates,
+  link_rate);
+   if (link_rate_index > 0) {
+   intel_dp->fallback_link_rate_index = link_rate_index - 1;
+   intel_dp->fallback_link_rate = 
common_rates[intel_dp->fallback_link_rate_index];
+   intel_dp->fallback_lane_count = 
intel_dp_max_lane_count(intel_dp);
+   } else if (lane_count > 1) {
+   intel_dp->fallback_link_rate_index = common_len - 1;
+   intel_dp->fallback_link_rate = 
common_rates[intel_dp->fallback_link_rate_index];
+   intel_dp->fallback_lane_count = lane_count >> 1;
+   } else {
+   DRM_ERROR("Link Training Unsuccessful\n");
+   return -1;
+   }
+
+   return 0;
+}
+
 static enum drm_mode_status
 intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 856dd41..4a49a2d 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -888,6 +888,10 @@ struct intel_dp {
uint32_t DP;
int link_rate;
uint8_t lane_count;
+   int fallback_link_rate;
+   uint8_t fallback_lane_count;
+   int fallback_link_rate_index;
+   bool link_train_failed;
uint8_t sink_count;
bool link_mst;
bool has_audio;
@@ -1386,6 +1390,8 @@ int intel_dp_set_link_status_property(struct 
drm_connector *connector,
 void intel_dp_set_link_params(struct intel_dp *intel_dp,
  int link_rate, uint8_t lane_count,
  bool link_mst);
+int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+   int link_rate, uint8_t lane_count);
 void intel_dp_start_link_train(struct intel_dp *intel_dp);
 void intel_dp_stop_link_train(struct intel_dp *intel_dp);
 void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
-- 
1.9.1

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