Re: [PATCH v6 5/8] drm/i915/lobf: Add debug interface for lobf

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 20 Mar 2025, Animesh Manna <animesh.manna@intel.com> wrote:
> Add an interface in debugfs which will help in debugging LOBF
> feature.
>
> v1: Initial version.
> v2:
> - Remove FORCE_EN flag. [Jouni]
> - Change prefix from I915 to INTEL. [Jani]
> - Use u8 instead of bool for lobf-debug flag. [Jani]
> v3:
> - Use intel_connector instead of display. [Jani]
> - Remove edp connector check as it was already present
> in caller function. [Jani]
> - Remove loop of searching edp encoder which is directly
> accessible from intel_connector. [Jani]
> v4:
> - Simplify alpm debug to bool instead of bit-mask. [Jani]
>
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_alpm.c     | 32 +++++++++++++++++++
>  .../drm/i915/display/intel_display_types.h    |  1 +
>  2 files changed, 33 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 5df1253a6b6c..dc24772743b8 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -276,6 +276,9 @@ void intel_alpm_lobf_compute_config(struct intel_dp *intel_dp,
>  	int waketime_in_lines, first_sdp_position;
>  	int context_latency, guardband;
>  
> +	if (intel_dp->alpm_parameters.lobf_enable_debug)
> +		return;
> +
>  	if (!intel_dp_is_edp(intel_dp))
>  		return;
>  
> @@ -436,6 +439,32 @@ static int i915_edp_lobf_info_show(struct seq_file *m, void *data)
>  
>  DEFINE_SHOW_ATTRIBUTE(i915_edp_lobf_info);
>  
> +static int
> +i915_edp_lobf_debug_get(void *data, u64 *val)
> +{
> +	struct intel_connector *connector = data;
> +	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
> +
> +	*val = READ_ONCE(intel_dp->alpm_parameters.lobf_enable_debug);

Why READ_ONCE()?

> +
> +	return 0;
> +}
> +
> +static int
> +i915_edp_lobf_debug_set(void *data, u64 val)
> +{
> +	struct intel_connector *connector = data;
> +	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
> +
> +	intel_dp->alpm_parameters.lobf_enable_debug = val;
> +
> +	return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(i915_edp_lobf_debug_fops,
> +			i915_edp_lobf_debug_get, i915_edp_lobf_debug_set,
> +			"%llu\n");
> +
>  void intel_alpm_lobf_debugfs_add(struct intel_connector *connector)
>  {
>  	struct intel_display *display = to_intel_display(connector);
> @@ -445,6 +474,9 @@ void intel_alpm_lobf_debugfs_add(struct intel_connector *connector)
>  	    connector->base.connector_type != DRM_MODE_CONNECTOR_eDP)
>  		return;
>  
> +	debugfs_create_file("i915_edp_lobf_debug", 0644, root,
> +			    connector, &i915_edp_lobf_debug_fops);
> +
>  	debugfs_create_file("i915_edp_lobf_info", 0444, root,
>  			    connector, &i915_edp_lobf_info_fops);
>  }
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index bef54b23273f..0b109aac5306 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1812,6 +1812,7 @@ struct intel_dp {
>  		u8 aux_less_wake_lines;
>  		u8 silence_period_sym_clocks;
>  		u8 lfps_half_cycle_num_of_syms;
> +		bool lobf_enable_debug;
>  	} alpm_parameters;
>  
>  	u8 alpm_dpcd;

-- 
Jani Nikula, Intel