Re: [PATCH v5 5/8] drm/i915/lobf: Add debug interface for lobf

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

On Fri, 07 Mar 2025, "Hogander, Jouni" <jouni.hogander@intel.com> wrote:
> On Mon, 2025-03-03 at 14:05 +0530, Animesh Manna 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]
>>
>> 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    |  5 +++
>>  2 files changed, 37 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
>> b/drivers/gpu/drm/i915/display/intel_alpm.c
>> index f4586c76a7b7..245364d031c1 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 &
>> INTEL_LOBF_DEBUG_DISABLE)
>> +             return;
>> +
>>       if (!intel_dp_is_edp(intel_dp))
>>               return;
>>
>> @@ -451,6 +454,32 @@ 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_debug);
>> +
>> +     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_debug = val;
>
> I think you should do some sanity check with the value from user space.

I don't understand why we're doing some bitmask stuff here in the first
place, when it's actually just a true/false thing.

BR,
Jani.


>
>> +     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);
>> @@ -460,6 +489,9 @@ 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 b78721c451b8..b6ec9a8fadd9 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
>> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
>> @@ -1808,6 +1808,11 @@ struct intel_dp {
>>               u8 aux_less_wake_lines;
>>               u8 silence_period_sym_clocks;
>>               u8 lfps_half_cycle_num_of_syms;
>> +
>> +#define INTEL_LOBF_DEBUG_MODE_MASK           0x0f
>
> 0x1?
>
> BR,
>
> Jouni Högander
>
>> +#define INTEL_LOBF_DEBUG_DEFAULT             0x00
>> +#define INTEL_LOBF_DEBUG_DISABLE             0x01
>> +             u8 lobf_debug;
>>       } alpm_parameters;
>>
>>       u8 alpm_dpcd;
>

-- 
Jani Nikula, Intel