Hi Ville,

On 25-Oct-23 6:29 PM, Ville Syrjälä wrote:
On Wed, Oct 18, 2023 at 04:24:00PM +0300, Stanislav Lisovskiy 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)

v4: - Apply the changes to proper function(Jani Nikula)

Signed-off-by: Stanislav Lisovskiy <[email protected]>
---
  .../drm/i915/display/intel_display_debugfs.c  | 66 +++++++++++++++++++
  .../drm/i915/display/intel_display_types.h    |  2 +
  drivers/gpu/drm/i915/display/intel_dp.c       |  6 +-
  3 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c 
b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index fbe75d47a165..9b810c6f96ea 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -1398,6 +1398,30 @@ 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 = 0;
+
+       if (!encoder)
+               return -ENODEV;
+
+       crtc = connector->base.state->crtc;
+       if (connector->base.status != connector_status_connected || !crtc) {
+               ret = -ENODEV;

Why do we need this extra complication?

+               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)
@@ -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 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);
+       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) {

eDP missing

+               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 4f6835a7578e..6a9148232a9c 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");

That's going to cause excessive dmesg spam.

Then how from dmesg we will get to know, big joiner was forced? Shouldn't we have atleast one debug print to know this?


+
+       return clock > i915->max_dotclk_freq || hdisplay > 5120 ||
+              intel_dp->force_bigjoiner_enable;
  }
static enum drm_mode_status
--
2.37.3

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