Re: [Intel-gfx] [RFC 1/3] drm/i915/power: move dc state members to struct i915_power_domains

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

On Fri, 03 Feb 2023, Imre Deak <imre.deak@intel.com> wrote:
> On Thu, Feb 02, 2023 at 10:47:46PM +0200, Jani Nikula wrote:
>> There's only one reference to the struct intel_dmc members dc_state,
>> target_dc_state, and allowed_dc_mask within intel_dmc.c, begging the
>> question why they are under struct intel_dmc to begin with.
>> 
>> Moreover, the only references to i915->display.dmc outside of
>> intel_dmc.c are to these members.
>> 
>> They don't belong. Move them from struct intel_dmc to struct
>> i915_power_domains, which seems like a more suitable place.
>> 
>> Cc: Imre Deak <imre.deak@intel.com>
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> ---
>> [...]
>>
>> @@ -481,7 +482,7 @@ void intel_dmc_load_program(struct drm_i915_private *dev_priv)
>>  		}
>>  	}
>>  
>> -	dev_priv->display.dmc.dc_state = 0;
>> +	power_domains->dc_state = 0;
>
> This could be dropped as well, as it's already inited by the time the
> function is called.

The whole dc_state thing originates to 832dba889e27 ("drm/i915/gen9:
Check for DC state mismatch"), and it's all about detecting
mismatches. I'm not sure how that works and if it's still useful.

> I agree with making struct intel_dmc internal to intel_dmc.c. Since DC
> state is a functionality provided by the firmware (except of DC9), an
> alternative would be to move/add get/set/assert etc. DC state functions
> to intel_dmc.c instead and call these from intel_display_power*.c.

That was actually the first patch I wrote but didn't send. There were a
few reasons I switched to this one:

First, it adds a dependency between power well and dmc initialization.

Second, it's a bunch of boilerplate, six get/set functions altogether,
and all of them checking for dmc init in patch 3.

Third, it still seems funny to have these members stored in intel_dmc,
accessed via intel_dmc.c, but intel_dmc.c not actually using them for
anything internally. It's only the power well code that uses
them. Should more of the DC state handling be moved to intel_dmc.c then?


BR,
Jani.


>
>>  
>>  	gen9_set_dc_state_debugmask(dev_priv);
>>  
>> diff --git a/drivers/gpu/drm/i915/display/intel_dmc.h b/drivers/gpu/drm/i915/display/intel_dmc.h
>> index 88eae74dbcf2..da8ba246013e 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dmc.h
>> +++ b/drivers/gpu/drm/i915/display/intel_dmc.h
>> @@ -40,9 +40,6 @@ struct intel_dmc {
>>  		bool present;
>>  	} dmc_info[DMC_FW_MAX];
>>  
>> -	u32 dc_state;
>> -	u32 target_dc_state;
>> -	u32 allowed_dc_mask;
>>  	intel_wakeref_t wakeref;
>>  };
>>  
>> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
>> index 2954759e9d12..cf13580af34a 100644
>> --- a/drivers/gpu/drm/i915/display/intel_psr.c
>> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
>> @@ -702,6 +702,7 @@ tgl_dc3co_exitline_compute_config(struct intel_dp *intel_dp,
>>  {
>>  	const u32 crtc_vdisplay = crtc_state->uapi.adjusted_mode.crtc_vdisplay;
>>  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
>> +	struct i915_power_domains *power_domains = &dev_priv->display.power.domains;
>>  	u32 exit_scanlines;
>>  
>>  	/*
>> @@ -718,7 +719,7 @@ tgl_dc3co_exitline_compute_config(struct intel_dp *intel_dp,
>>  	if (crtc_state->enable_psr2_sel_fetch)
>>  		return;
>>  
>> -	if (!(dev_priv->display.dmc.allowed_dc_mask & DC_STATE_EN_DC3CO))
>> +	if (!(power_domains->allowed_dc_mask & DC_STATE_EN_DC3CO))
>>  		return;
>>  
>>  	if (!dc3co_is_pipe_port_compatible(intel_dp, crtc_state))
>> -- 
>> 2.34.1
>> 

-- 
Jani Nikula, Intel Open Source Graphics Center