Re: [PATCH 2/5] drm/i915: Parse EDID probed modes for DRRS support

[Vandana Kannan <vandana.kannan@intel.com>]

On Dec-17-2013 5:58 PM, Chris Wilson wrote:
> On Tue, Dec 17, 2013 at 10:58:24AM +0530, Vandana Kannan wrote:
>> From: Pradeep Bhat <pradeep.bhat@intel.com>
>>
>> This patch and finds out the lowest refresh rate supported for the resolution
>> same as the fixed_mode, based on the implementaion find_panel_downclock.
>> It also checks the VBT fields to see if panel supports seamless DRRS or not.
>> Based on above data it marks whether eDP panel supports seamless DRRS or not.
>> This information is needed for supporting seamless DRRS switch for
>> certain power saving usecases. This patch is tested by enabling the DRM logs
>> and user should see whether Seamless DRRS is supported or not.
>>
>> Signed-off-by: Pradeep Bhat <pradeep.bhat@intel.com>
>> Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_drv.h  |    2 ++
>>  drivers/gpu/drm/i915/intel_dp.c  |   47 ++++++++++++++++++++++++++++++++++++++
>>  drivers/gpu/drm/i915/intel_drv.h |   29 +++++++++++++++++++++++
>>  3 files changed, 78 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> index 02e11dc..c9bca16 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -1462,8 +1462,10 @@ typedef struct drm_i915_private {
>>  	/* Reclocking support */
>>  	bool render_reclock_avail;
>>  	bool lvds_downclock_avail;
>> +	bool edp_downclock_avail;
>>  	/* indicates the reduced downclock for LVDS*/
>>  	int lvds_downclock;
>> +	int edp_downclock;
>>  	u16 orig_clock;
> 
> Do any machines have both edp and lvds? Shouldn't this be a part of the
> panel state?
>
If there is a machine having both edp and lvds, then edp takes higher
priority. edp_downclock_avail and edp_downclock were added here
following the existing code having lvds_downclock_avail and
lvds_downclock here. If required, edp_downclock_avail and edp_downclock
can be moved to intel_panel structure. Kindly let us know.

>>  
>> +/**
>> + * This enum is used to indicate the DRRS support type.
>> + * The values of the enum map 1-to-1 with the values from VBT.
>> + */
>> +enum edp_panel_type {
>> +	DRRS_NOT_SUPPORTED = -1,
>> +	STATIC_DRRS_SUPPORT = 0,
>> +	SEAMLESS_DRRS_SUPPORT = 2
>> +};
>> +/**
>> + * HIGH_RR is the highest eDP panel refresh rate read from EDID
>> + * LOW_RR is the lowest eDP panel refresh rate found from EDID
>> + * parsing for same resolution.
>> + */
>> +enum edp_drrs_refresh_rate_type {
>> +	DRRS_HIGH_RR,
>> +	DRRS_LOW_RR,
>> +	DRRS_MAX_RR, /* RR count */
>> +};
>> +/**
>> + * The drrs_info struct will represent the DRRS feature for eDP
>> + * panel.
>> + */
>> +struct drrs_info {
>> +	int is_drrs_supported;
>> +	int drrs_refresh_rate_type;
> 
> So what was the point of the enums again? Are you purposely trying to
> disable gcc and sparse's type-safety?
> -Chris
> 
The enum edp_panel_type is required to check DRRS capability of the
panel before performing any enabling. We will look into an
implementation which can do without edp_drrs_refresh_rate_type.