Re: [PATCH] drm/i915: Add bigjoiner force enable option to debugfs

["Modem, Bhanuprakash" <bhanuprakash.modem@xxxxxxxxx>]

On Thu-16-11-2023 04:07 pm, 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.

Do we have any IGT to validate this?

- Bhanu

> 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)
>
> v5: - Removed unnecessary check from i915_bigjoiner_enable_show
>        (Ville Syrjälä)
>      - Added eDP connector check to intel_connector_debugfs_add
>        (Ville Syrjälä)
>      - Removed debug message in order to prevent dmesg flooding
>        (Ville Syrjälä)
>
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
> ---
>   .../drm/i915/display/intel_display_debugfs.c  | 59 +++++++++++++++++++
>   .../drm/i915/display/intel_display_types.h    |  2 +
>   drivers/gpu/drm/i915/display/intel_dp.c       |  3 +-
>   3 files changed, 63 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 915420d0cef8f..aa95ecf2458ee 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -1414,6 +1414,22 @@ 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 intel_encoder *encoder = intel_attached_encoder(connector);
> +	struct intel_dp *intel_dp;
> +
> +	if (!encoder)
> +		return -ENODEV;
> +
> +	intel_dp = enc_to_intel_dp(encoder);
> +
> +	seq_printf(m, "Bigjoiner enable: %d\n", intel_dp->force_bigjoiner_enable);
> +
> +	return 0;
> +}
> +
>   static ssize_t i915_dsc_output_format_write(struct file *file,
>   					    const char __user *ubuf,
>   					    size_t len, loff_t *offp)
> @@ -1435,12 +1451,39 @@ 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,
> @@ -1529,6 +1572,15 @@ static const struct file_operations i915_dsc_fractional_bpp_fops = {
>   	.write = i915_dsc_fractional_bpp_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
> @@ -1611,6 +1663,13 @@ void intel_connector_debugfs_add(struct intel_connector *intel_connector)
>   				    connector, &i915_dsc_fractional_bpp_fops);
>   	}
>   
> +	if (DISPLAY_VER(dev_priv) >= 11 &&
> +	    (intel_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> +	     intel_connector->base.connector_type == DRM_MODE_CONNECTOR_eDP)) {
> +		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 9a44350ba05dd..559302ff79c1a 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1764,6 +1764,8 @@ 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 54bd0bffa9f08..5b8411b9fc30b 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1172,7 +1172,8 @@ 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;
> +	return clock > i915->max_dotclk_freq || hdisplay > 5120 ||
> +	       intel_dp->force_bigjoiner_enable;
>   }
>   
>   static enum drm_mode_status