Re: [PATCH v2 05/13] drm/i915/display: Add DC3CO support check and validate target DC state

[Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahmanian@intel.com>]

On 29-04-2026 10:43, Manna, Animesh wrote:
>
>> -----Original Message-----
>> From: Dibin Moolakadan Subrahmanian
>> <dibin.moolakadan.subrahmanian@intel.com>
>> Sent: Wednesday, April 22, 2026 9:56 PM
>> To: intel-gfx@lists.freedesktop.org; intel-xe@lists.freedesktop.org
>> Cc: Manna, Animesh <animesh.manna@intel.com>; Shankar, Uma
>> <uma.shankar@intel.com>; Kurmi, Suresh Kumar
>> <suresh.kumar.kurmi@intel.com>
>> Subject: [PATCH v2 05/13] drm/i915/display: Add DC3CO support check and
>> validate target DC state
>>
>> Validate the requested target DC state against allowed_dc_mask in
>> intel_display_power_set_target_dc_state() to avoid programming
>> unsupported DC states.
>>
>> Also add intel_display_power_dc3co_supported() helper to query DC3CO
>> support from allowed_dc_mask.
>>
>> Changes in v2:
>> - Squash "Add helper to check DC3CO support" patch into this patch
>>
>> Signed-off-by: Dibin Moolakadan Subrahmanian
>> <dibin.moolakadan.subrahmanian@intel.com>
>> Reviewed-by: Uma Shankar <uma.shankar@intel.com>
>> ---
>>   drivers/gpu/drm/i915/display/intel_display_power.c | 14 ++++++++++++++
>> drivers/gpu/drm/i915/display/intel_display_power.h |  1 +
>>   2 files changed, 15 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c
>> b/drivers/gpu/drm/i915/display/intel_display_power.c
>> index 77c32492caa1..f626803bbd88 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
>> @@ -302,6 +302,13 @@ void
>> intel_display_power_set_target_dc_state(struct intel_display *display,
>>   	struct i915_power_domains *power_domains = &display-
>>> power.domains;
>>   	mutex_lock(&power_domains->lock);
>> +
>> +	if ((state & power_domains->allowed_dc_mask) != state) {
>> +		drm_dbg_kms(display->drm,
>> +			    "Rejecting DC state 0x%x (allowed mask 0x%x)\n",
>> +			     state, power_domains->allowed_dc_mask);
>> +		goto unlock;
>> +	}
>>   	power_well = lookup_power_well(display, SKL_DISP_DC_OFF);
>>
>>   	if (drm_WARN_ON(display->drm, !power_well)) @@ -358,6 +365,13
>> @@ u32 intel_display_power_get_current_dc_state(struct intel_display
>> *display)
>>   	return current_dc_state;
>>   }
>>
>> +bool intel_display_power_dc3co_supported(struct intel_display *display)
>> +{
>> +	struct i915_power_domains *power_domains = &display-
>>> power.domains;
>> +
>> +	return (power_domains->allowed_dc_mask &
>> DC_STATE_EN_UPTO_DC3CO) ==
>> +DC_STATE_EN_UPTO_DC3CO; }
>> +
> allowed_dc_mask is not set in this patch series, which I presume will be based on HAS_DC3CO() check.
> Could not differentiate between intel_display_power_dc3co_supported() and HAS_DC3CO() and both are dependent only on DISPLAY_VER() like if platform is supporting or not.

HAS_DC3CO() checks for the HW capablity.
intel_display_power_dc3co_supported() checks if dc3co is supported at runtime.
it check DC3CO against power_domains->allowed_dc_mask which is assigned at in intel_power_domains_init()
based on params.enable_dc , allowing the feature to be controlled via module parameters.

> Regards,
> Animesh
>
>>   static void __async_put_domains_mask(struct i915_power_domains
>> *power_domains,
>>   				     struct intel_power_domain_mask *mask)
>> { diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h
>> b/drivers/gpu/drm/i915/display/intel_display_power.h
>> index d616d5d09cbe..05880e9da89f 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_power.h
>> +++ b/drivers/gpu/drm/i915/display/intel_display_power.h
>> @@ -186,6 +186,7 @@ void intel_display_power_resume(struct intel_display
>> *display);  void intel_display_power_set_target_dc_state(struct intel_display
>> *display,
>>   					     u32 state);
>>   u32 intel_display_power_get_current_dc_state(struct intel_display
>> *display);
>> +bool intel_display_power_dc3co_supported(struct intel_display
>> +*display);
>>
>>   bool intel_display_power_is_enabled(struct intel_display *display,
>>   				    enum intel_display_power_domain
>> domain);
>> --
>> 2.43.0