diff mbox series

drm/i915: Add bigjoiner force enable option to debugfs

Message ID 20231012123411.17241-1-stanislav.lisovskiy@intel.com (mailing list archive)
State New, archived
Headers show
Series drm/i915: Add bigjoiner force enable option to debugfs | expand

Commit Message

Stanislav Lisovskiy Oct. 12, 2023, 12:34 p.m. UTC
For validation purposes, it might be useful to be able to
force Bigjoiner mode, even if current dotclock/resolution
do not require that.
Lets add such to option to debugfs.

v2: - Apparently intel_dp_need_bigjoiner can't be used, when
      debugfs entry is created so lets just check manually
      the DISPLAY_VER.

v3: - Switch to intel_connector from drm_connector(Jani Nikula)
    - Remove redundant modeset lock(Jani Nikula)
    - Use kstrtobool_from_user for boolean value(Jani Nikula)

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
---
 .../drm/i915/display/intel_display_debugfs.c  | 72 ++++++++++++++++++-
 .../drm/i915/display/intel_display_types.h    |  2 +
 drivers/gpu/drm/i915/display/intel_dp.c       |  6 +-
 3 files changed, 76 insertions(+), 4 deletions(-)

Comments

Jani Nikula Oct. 12, 2023, 2:59 p.m. UTC | #1
On Thu, 12 Oct 2023, Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> wrote:
> For validation purposes, it might be useful to be able to
> force Bigjoiner mode, even if current dotclock/resolution
> do not require that.
> Lets add such to option to debugfs.
>
> v2: - Apparently intel_dp_need_bigjoiner can't be used, when
>       debugfs entry is created so lets just check manually
>       the DISPLAY_VER.
>
> v3: - Switch to intel_connector from drm_connector(Jani Nikula)
>     - Remove redundant modeset lock(Jani Nikula)
>     - Use kstrtobool_from_user for boolean value(Jani Nikula)
>
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> ---
>  .../drm/i915/display/intel_display_debugfs.c  | 72 ++++++++++++++++++-
>  .../drm/i915/display/intel_display_types.h    |  2 +
>  drivers/gpu/drm/i915/display/intel_dp.c       |  6 +-
>  3 files changed, 76 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index fbe75d47a165..dea7bbea83ba 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -1398,13 +1398,37 @@ out:	drm_modeset_unlock(&dev->mode_config.connection_mutex);
>  	return ret;
>  }
>  
> +static int i915_bigjoiner_enable_show(struct seq_file *m, void *data)
> +{
> +	struct intel_connector *connector = to_intel_connector(m->private);
> +	struct drm_crtc *crtc;
> +	struct intel_encoder *encoder = intel_attached_encoder(connector);
> +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> +	int ret;
> +
> +	if (!encoder)
> +		return -ENODEV;
> +
> +	crtc = connector->base.state->crtc;
> +	if (connector->base.status != connector_status_connected || !crtc) {
> +		ret = -ENODEV;
> +		goto out;
> +	}
> +
> +	seq_printf(m, "Bigjoiner enable: %d\n", intel_dp->force_bigjoiner_enable);
> +
> +out:
> +
> +	return ret;
> +}
> +
>  static ssize_t i915_dsc_output_format_write(struct file *file,
>  					    const char __user *ubuf,
>  					    size_t len, loff_t *offp)
>  {
> -	struct drm_connector *connector =
> -		((struct seq_file *)file->private_data)->private;
> -	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
> +	struct seq_file *m = file->private_data;
> +        struct intel_connector *connector = m->private;
> +	struct intel_encoder *encoder = intel_attached_encoder(connector);

Ooops, I think you made those changes to the wrong function there. ;)

>  	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>  	int dsc_output_format = 0;
>  	int ret;
> @@ -1419,12 +1443,39 @@ static ssize_t i915_dsc_output_format_write(struct file *file,
>  	return len;
>  }
>  
> +static ssize_t i915_bigjoiner_enable_fops_write(struct file *file,
> +						const char __user *ubuf,
> +						size_t len, loff_t *offp)
> +{
> +	struct drm_connector *connector =
> +		((struct seq_file *)file->private_data)->private;
> +	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));

Should be here.

> +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> +	bool bigjoiner_en = 0;
> +	int ret;
> +
> +	ret = kstrtobool_from_user(ubuf, len, &bigjoiner_en);
> +	if (ret < 0)
> +		return ret;
> +
> +	intel_dp->force_bigjoiner_enable = bigjoiner_en;
> +	*offp += len;
> +
> +	return len;
> +}
> +
>  static int i915_dsc_output_format_open(struct inode *inode,
>  				       struct file *file)
>  {
>  	return single_open(file, i915_dsc_output_format_show, inode->i_private);
>  }
>  
> +static int i915_bigjoiner_enable_open(struct inode *inode,
> +				      struct file *file)
> +{
> +	return single_open(file, i915_bigjoiner_enable_show, inode->i_private);
> +}
> +
>  static const struct file_operations i915_dsc_output_format_fops = {
>  	.owner = THIS_MODULE,
>  	.open = i915_dsc_output_format_open,
> @@ -1434,6 +1485,15 @@ static const struct file_operations i915_dsc_output_format_fops = {
>  	.write = i915_dsc_output_format_write
>  };
>  
> +static const struct file_operations i915_bigjoiner_enable_fops = {
> +	.owner = THIS_MODULE,
> +	.open = i915_bigjoiner_enable_open,
> +	.read = seq_read,
> +	.llseek = seq_lseek,
> +	.release = single_release,
> +	.write = i915_bigjoiner_enable_fops_write
> +};
> +
>  /*
>   * Returns the Current CRTC's bpc.
>   * Example usage: cat /sys/kernel/debug/dri/0/crtc-0/i915_current_bpc
> @@ -1513,6 +1573,12 @@ void intel_connector_debugfs_add(struct intel_connector *intel_connector)
>  				    connector, &i915_dsc_output_format_fops);
>  	}
>  
> +	if (DISPLAY_VER(dev_priv) >= 11 &&
> +	    intel_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
> +		debugfs_create_file("i915_bigjoiner_force_enable", 0644, root,
> +				    &intel_connector->base, &i915_bigjoiner_enable_fops);
> +	}
> +
>  	if (connector->connector_type == DRM_MODE_CONNECTOR_DSI ||
>  	    connector->connector_type == DRM_MODE_CONNECTOR_eDP ||
>  	    connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 8d8b2f8d37a9..e0de6eeaf59e 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1753,6 +1753,8 @@ struct intel_dp {
>  	bool is_mst;
>  	int active_mst_links;
>  
> +	bool force_bigjoiner_enable;
> +
>  	/* connector directly attached - won't be use for modeset in mst world */
>  	struct intel_connector *attached_connector;
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 0ef7cb8134b6..daf9bc0d6838 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1153,7 +1153,11 @@ bool intel_dp_need_bigjoiner(struct intel_dp *intel_dp,
>  	if (!intel_dp_can_bigjoiner(intel_dp))
>  		return false;
>  
> -	return clock > i915->max_dotclk_freq || hdisplay > 5120;
> +	if (intel_dp->force_bigjoiner_enable)
> +		drm_dbg_kms(&i915->drm, "Forcing bigjoiner mode\n");
> +
> +	return clock > i915->max_dotclk_freq || hdisplay > 5120 ||
> +	       intel_dp->force_bigjoiner_enable;
>  }
>  
>  static enum drm_mode_status
Stanislav Lisovskiy Oct. 13, 2023, 9:54 a.m. UTC | #2
On Thu, Oct 12, 2023 at 05:59:18PM +0300, Jani Nikula wrote:
> On Thu, 12 Oct 2023, Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> wrote:
> > For validation purposes, it might be useful to be able to
> > force Bigjoiner mode, even if current dotclock/resolution
> > do not require that.
> > Lets add such to option to debugfs.
> >
> > v2: - Apparently intel_dp_need_bigjoiner can't be used, when
> >       debugfs entry is created so lets just check manually
> >       the DISPLAY_VER.
> >
> > v3: - Switch to intel_connector from drm_connector(Jani Nikula)
> >     - Remove redundant modeset lock(Jani Nikula)
> >     - Use kstrtobool_from_user for boolean value(Jani Nikula)
> >
> > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > ---
> >  .../drm/i915/display/intel_display_debugfs.c  | 72 ++++++++++++++++++-
> >  .../drm/i915/display/intel_display_types.h    |  2 +
> >  drivers/gpu/drm/i915/display/intel_dp.c       |  6 +-
> >  3 files changed, 76 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > index fbe75d47a165..dea7bbea83ba 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > @@ -1398,13 +1398,37 @@ out:	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> >  	return ret;
> >  }
> >  
> > +static int i915_bigjoiner_enable_show(struct seq_file *m, void *data)
> > +{
> > +	struct intel_connector *connector = to_intel_connector(m->private);
> > +	struct drm_crtc *crtc;
> > +	struct intel_encoder *encoder = intel_attached_encoder(connector);
> > +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > +	int ret;
> > +
> > +	if (!encoder)
> > +		return -ENODEV;
> > +
> > +	crtc = connector->base.state->crtc;
> > +	if (connector->base.status != connector_status_connected || !crtc) {
> > +		ret = -ENODEV;
> > +		goto out;
> > +	}
> > +
> > +	seq_printf(m, "Bigjoiner enable: %d\n", intel_dp->force_bigjoiner_enable);
> > +
> > +out:
> > +
> > +	return ret;
> > +}
> > +
> >  static ssize_t i915_dsc_output_format_write(struct file *file,
> >  					    const char __user *ubuf,
> >  					    size_t len, loff_t *offp)
> >  {
> > -	struct drm_connector *connector =
> > -		((struct seq_file *)file->private_data)->private;
> > -	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
> > +	struct seq_file *m = file->private_data;
> > +        struct intel_connector *connector = m->private;
> > +	struct intel_encoder *encoder = intel_attached_encoder(connector);
> 
> Ooops, I think you made those changes to the wrong function there. ;)

Ouch, they looked exactly identical! I would say this could have been changed too,
but not in that patch indeed :)))
Thanks for spotting..probably really time to think about starting using glasses.

> 
> >  	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> >  	int dsc_output_format = 0;
> >  	int ret;
> > @@ -1419,12 +1443,39 @@ static ssize_t i915_dsc_output_format_write(struct file *file,
> >  	return len;
> >  }
> >  
> > +static ssize_t i915_bigjoiner_enable_fops_write(struct file *file,
> > +						const char __user *ubuf,
> > +						size_t len, loff_t *offp)
> > +{
> > +	struct drm_connector *connector =
> > +		((struct seq_file *)file->private_data)->private;
> > +	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
> 
> Should be here.
> 
> > +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > +	bool bigjoiner_en = 0;
> > +	int ret;
> > +
> > +	ret = kstrtobool_from_user(ubuf, len, &bigjoiner_en);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	intel_dp->force_bigjoiner_enable = bigjoiner_en;
> > +	*offp += len;
> > +
> > +	return len;
> > +}
> > +
> >  static int i915_dsc_output_format_open(struct inode *inode,
> >  				       struct file *file)
> >  {
> >  	return single_open(file, i915_dsc_output_format_show, inode->i_private);
> >  }
> >  
> > +static int i915_bigjoiner_enable_open(struct inode *inode,
> > +				      struct file *file)
> > +{
> > +	return single_open(file, i915_bigjoiner_enable_show, inode->i_private);
> > +}
> > +
> >  static const struct file_operations i915_dsc_output_format_fops = {
> >  	.owner = THIS_MODULE,
> >  	.open = i915_dsc_output_format_open,
> > @@ -1434,6 +1485,15 @@ static const struct file_operations i915_dsc_output_format_fops = {
> >  	.write = i915_dsc_output_format_write
> >  };
> >  
> > +static const struct file_operations i915_bigjoiner_enable_fops = {
> > +	.owner = THIS_MODULE,
> > +	.open = i915_bigjoiner_enable_open,
> > +	.read = seq_read,
> > +	.llseek = seq_lseek,
> > +	.release = single_release,
> > +	.write = i915_bigjoiner_enable_fops_write
> > +};
> > +
> >  /*
> >   * Returns the Current CRTC's bpc.
> >   * Example usage: cat /sys/kernel/debug/dri/0/crtc-0/i915_current_bpc
> > @@ -1513,6 +1573,12 @@ void intel_connector_debugfs_add(struct intel_connector *intel_connector)
> >  				    connector, &i915_dsc_output_format_fops);
> >  	}
> >  
> > +	if (DISPLAY_VER(dev_priv) >= 11 &&
> > +	    intel_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
> > +		debugfs_create_file("i915_bigjoiner_force_enable", 0644, root,
> > +				    &intel_connector->base, &i915_bigjoiner_enable_fops);
> > +	}
> > +
> >  	if (connector->connector_type == DRM_MODE_CONNECTOR_DSI ||
> >  	    connector->connector_type == DRM_MODE_CONNECTOR_eDP ||
> >  	    connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> > index 8d8b2f8d37a9..e0de6eeaf59e 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1753,6 +1753,8 @@ struct intel_dp {
> >  	bool is_mst;
> >  	int active_mst_links;
> >  
> > +	bool force_bigjoiner_enable;
> > +
> >  	/* connector directly attached - won't be use for modeset in mst world */
> >  	struct intel_connector *attached_connector;
> >  
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 0ef7cb8134b6..daf9bc0d6838 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -1153,7 +1153,11 @@ bool intel_dp_need_bigjoiner(struct intel_dp *intel_dp,
> >  	if (!intel_dp_can_bigjoiner(intel_dp))
> >  		return false;
> >  
> > -	return clock > i915->max_dotclk_freq || hdisplay > 5120;
> > +	if (intel_dp->force_bigjoiner_enable)
> > +		drm_dbg_kms(&i915->drm, "Forcing bigjoiner mode\n");
> > +
> > +	return clock > i915->max_dotclk_freq || hdisplay > 5120 ||
> > +	       intel_dp->force_bigjoiner_enable;
> >  }
> >  
> >  static enum drm_mode_status
> 
> -- 
> Jani Nikula, Intel
kernel test robot Oct. 17, 2023, 9:49 a.m. UTC | #3
Hi Stanislav,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-tip/drm-tip]

url:    https://github.com/intel-lab-lkp/linux/commits/Stanislav-Lisovskiy/drm-i915-Add-bigjoiner-force-enable-option-to-debugfs/20231017-105841
base:   git://anongit.freedesktop.org/drm/drm-tip drm-tip
patch link:    https://lore.kernel.org/r/20231012123411.17241-1-stanislav.lisovskiy%40intel.com
patch subject: [Intel-gfx] [PATCH] drm/i915: Add bigjoiner force enable option to debugfs
config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20231017/202310171756.yzfTKqav-lkp@intel.com/config)
compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231017/202310171756.yzfTKqav-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310171756.yzfTKqav-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/i915/display/intel_display_debugfs.c:1413:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           if (connector->base.status != connector_status_connected || !crtc) {
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/i915/display/intel_display_debugfs.c:1422:9: note: uninitialized use occurs here
           return ret;
                  ^~~
   drivers/gpu/drm/i915/display/intel_display_debugfs.c:1413:2: note: remove the 'if' if its condition is always true
           if (connector->base.status != connector_status_connected || !crtc) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/gpu/drm/i915/display/intel_display_debugfs.c:1407:9: note: initialize the variable 'ret' to silence this warning
           int ret;
                  ^
                   = 0
   1 warning generated.


vim +1413 drivers/gpu/drm/i915/display/intel_display_debugfs.c

  1400	
  1401	static int i915_bigjoiner_enable_show(struct seq_file *m, void *data)
  1402	{
  1403		struct intel_connector *connector = to_intel_connector(m->private);
  1404		struct drm_crtc *crtc;
  1405		struct intel_encoder *encoder = intel_attached_encoder(connector);
  1406		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
  1407		int ret;
  1408	
  1409		if (!encoder)
  1410			return -ENODEV;
  1411	
  1412		crtc = connector->base.state->crtc;
> 1413		if (connector->base.status != connector_status_connected || !crtc) {
  1414			ret = -ENODEV;
  1415			goto out;
  1416		}
  1417	
  1418		seq_printf(m, "Bigjoiner enable: %d\n", intel_dp->force_bigjoiner_enable);
  1419	
  1420	out:
  1421	
  1422		return ret;
  1423	}
  1424
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index fbe75d47a165..dea7bbea83ba 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -1398,13 +1398,37 @@  out:	drm_modeset_unlock(&dev->mode_config.connection_mutex);
 	return ret;
 }
 
+static int i915_bigjoiner_enable_show(struct seq_file *m, void *data)
+{
+	struct intel_connector *connector = to_intel_connector(m->private);
+	struct drm_crtc *crtc;
+	struct intel_encoder *encoder = intel_attached_encoder(connector);
+	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+	int ret;
+
+	if (!encoder)
+		return -ENODEV;
+
+	crtc = connector->base.state->crtc;
+	if (connector->base.status != connector_status_connected || !crtc) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	seq_printf(m, "Bigjoiner enable: %d\n", intel_dp->force_bigjoiner_enable);
+
+out:
+
+	return ret;
+}
+
 static ssize_t i915_dsc_output_format_write(struct file *file,
 					    const char __user *ubuf,
 					    size_t len, loff_t *offp)
 {
-	struct drm_connector *connector =
-		((struct seq_file *)file->private_data)->private;
-	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
+	struct seq_file *m = file->private_data;
+        struct intel_connector *connector = m->private;
+	struct intel_encoder *encoder = intel_attached_encoder(connector);
 	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 	int dsc_output_format = 0;
 	int ret;
@@ -1419,12 +1443,39 @@  static ssize_t i915_dsc_output_format_write(struct file *file,
 	return len;
 }
 
+static ssize_t i915_bigjoiner_enable_fops_write(struct file *file,
+						const char __user *ubuf,
+						size_t len, loff_t *offp)
+{
+	struct drm_connector *connector =
+		((struct seq_file *)file->private_data)->private;
+	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
+	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+	bool bigjoiner_en = 0;
+	int ret;
+
+	ret = kstrtobool_from_user(ubuf, len, &bigjoiner_en);
+	if (ret < 0)
+		return ret;
+
+	intel_dp->force_bigjoiner_enable = bigjoiner_en;
+	*offp += len;
+
+	return len;
+}
+
 static int i915_dsc_output_format_open(struct inode *inode,
 				       struct file *file)
 {
 	return single_open(file, i915_dsc_output_format_show, inode->i_private);
 }
 
+static int i915_bigjoiner_enable_open(struct inode *inode,
+				      struct file *file)
+{
+	return single_open(file, i915_bigjoiner_enable_show, inode->i_private);
+}
+
 static const struct file_operations i915_dsc_output_format_fops = {
 	.owner = THIS_MODULE,
 	.open = i915_dsc_output_format_open,
@@ -1434,6 +1485,15 @@  static const struct file_operations i915_dsc_output_format_fops = {
 	.write = i915_dsc_output_format_write
 };
 
+static const struct file_operations i915_bigjoiner_enable_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_bigjoiner_enable_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+	.write = i915_bigjoiner_enable_fops_write
+};
+
 /*
  * Returns the Current CRTC's bpc.
  * Example usage: cat /sys/kernel/debug/dri/0/crtc-0/i915_current_bpc
@@ -1513,6 +1573,12 @@  void intel_connector_debugfs_add(struct intel_connector *intel_connector)
 				    connector, &i915_dsc_output_format_fops);
 	}
 
+	if (DISPLAY_VER(dev_priv) >= 11 &&
+	    intel_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
+		debugfs_create_file("i915_bigjoiner_force_enable", 0644, root,
+				    &intel_connector->base, &i915_bigjoiner_enable_fops);
+	}
+
 	if (connector->connector_type == DRM_MODE_CONNECTOR_DSI ||
 	    connector->connector_type == DRM_MODE_CONNECTOR_eDP ||
 	    connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 8d8b2f8d37a9..e0de6eeaf59e 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1753,6 +1753,8 @@  struct intel_dp {
 	bool is_mst;
 	int active_mst_links;
 
+	bool force_bigjoiner_enable;
+
 	/* connector directly attached - won't be use for modeset in mst world */
 	struct intel_connector *attached_connector;
 
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 0ef7cb8134b6..daf9bc0d6838 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1153,7 +1153,11 @@  bool intel_dp_need_bigjoiner(struct intel_dp *intel_dp,
 	if (!intel_dp_can_bigjoiner(intel_dp))
 		return false;
 
-	return clock > i915->max_dotclk_freq || hdisplay > 5120;
+	if (intel_dp->force_bigjoiner_enable)
+		drm_dbg_kms(&i915->drm, "Forcing bigjoiner mode\n");
+
+	return clock > i915->max_dotclk_freq || hdisplay > 5120 ||
+	       intel_dp->force_bigjoiner_enable;
 }
 
 static enum drm_mode_status