Re: [PATCH v3 4/6] drm/i915/lobf: Add debug interface for lobf

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Mon, 2025-01-06 at 09:45 +0530, Animesh Manna wrote:
> Add an interface in debugfs which will help in debugging LOBF
> feature.
> 
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_alpm.c     | 51
> +++++++++++++++++++
>  .../drm/i915/display/intel_display_types.h    |  6 +++
>  2 files changed, 57 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 197c67363f0e..1cc0e5ed3f74 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_debug &
> I915_LOBF_DEBUG_DISABLE)
> +		return;
> +
>  	if (!intel_dp_is_edp(intel_dp))
>  		return;
>  
> @@ -448,6 +451,51 @@ 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_display *display = data;
> +	struct intel_encoder *encoder;
> +	int ret = -ENODEV;
> +
> +	for_each_intel_dp(display->drm, encoder) {
> +		struct intel_dp *intel_dp =
> enc_to_intel_dp(encoder);
> +
> +		if (!intel_dp_is_edp(intel_dp))
> +			return ret;
> +
> +		// TODO: split to each edp transcoder.
> +		*val = READ_ONCE(intel_dp-
> >alpm_parameters.lobf_debug);
> +		ret = 0;
> +	}
> +
> +	return ret;
> +}
> +
> +static int
> +i915_edp_lobf_debug_set(void *data, u64 val)
> +{
> +	struct intel_display *display = data;
> +	struct intel_encoder *encoder;
> +	int ret = -ENODEV;
> +
> +	for_each_intel_dp(display->drm, encoder) {
> +		struct intel_dp *intel_dp =
> enc_to_intel_dp(encoder);
> +
> +		if (!intel_dp_is_edp(intel_dp))
> +			return ret;
> +
> +		// TODO: split to each edp transcoder.
> +		intel_dp->alpm_parameters.lobf_debug = val;
> +	}
> +
> +	return ret;
> +}
> +
> +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);
> @@ -457,6 +505,9 @@ 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 f230163226d1..37f061acb204 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1800,6 +1800,12 @@ struct intel_dp {
>  		u8 aux_less_wake_lines;
>  		u8 silence_period_sym_clocks;
>  		u8 lfps_half_cycle_num_of_syms;
> +
> +#define I915_LOBF_DEBUG_MODE_MASK		0x0f
> +#define I915_LOBF_DEBUG_DEFAULT			0x00
> +#define I915_LOBF_DEBUG_DISABLE			0x01
> +#define I915_LOBF_DEBUG_FORCE_EN		0x02

FORCE_EN is not needed. You can achieve LOBF (if it's possible) by
disabling PSR/PR.

BR,

Jouni Högander

> +		bool lobf_debug;
>  	} alpm_parameters;
>  
>  	u8 alpm_dpcd;