Re: [PATCH v2 4/4] drm/i915/bw: Extract get_display_bw_params()

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

On Mon, 11 May 2026, Matt Roper <matthew.d.roper@intel.com> wrote:
> On Mon, May 11, 2026 at 01:30:59PM -0300, Gustavo Sousa wrote:
>> Just like it is done for the platform-specific bandwidth parameters, use
>> a separate function named get_display_bw_params() to return the display
>> IP-specific parameters.  This simplifies intel_bw_init_hw() by having
>> just one call for each of the *_get_bw_info() functions.
>> 
>> v2:
>>   - Prefer to call get_display_bw_params() only once in
>>     intel_bw_init_hw() instead of having multiple calls in each of the
>>     affected *_get_bw_info() functions. (Jani)
>> 
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
>> ---
>>  drivers/gpu/drm/i915/display/intel_bw.c | 36 +++++++++++++++++++++------------
>>  1 file changed, 23 insertions(+), 13 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
>> index c01356d38e64..acd1b6901b46 100644
>> --- a/drivers/gpu/drm/i915/display/intel_bw.c
>> +++ b/drivers/gpu/drm/i915/display/intel_bw.c
>> @@ -493,6 +493,26 @@ static const struct intel_display_bw_params xelpdp_bw_params = {
>>  	.displayrtids = 256,
>>  };
>>  
>> +static const struct intel_display_bw_params *get_display_bw_params(struct intel_display *display)
>> +{
>> +	if (DISPLAY_VER(display) >= 14) {
>> +		return &xelpdp_bw_params;
>> +	} else if (DISPLAY_VER(display) >= 12) {
>> +		/*
>> +		 * RKL's SoC was based on ICL and the display, even though being
>> +		 * gen12, had changes to the memory interface to match gen11's,
>> +		 * consequently inheriting gen11's display-specific bandwidth
>> +		 * parameters.
>> +		 */
>> +		if (display->platform.rocketlake)
>> +			return &gen11_bw_params;
>> +		else
>> +			return &gen12_bw_params;
>> +	} else {
>> +		return &gen11_bw_params;
>
> It doesn't really matter, but this is technically going to assign gen11
> parameters for all the pre-gen11 platforms that call through here on
> i915.  If we never use the values it probably doesn't hurt anything, but
> it might be best to make this a condition on gen11 rather than an 'else'
> just to avoid any confusion.
>
>
> Matt
>
>> +	}
>> +}
>> +
>>  static int icl_get_bw_info(struct intel_display *display,
>>  			   const struct dram_info *dram_info,
>>  			   const struct intel_soc_bw_params *soc_bw_params,
>> @@ -843,6 +863,7 @@ void intel_bw_init_hw(struct intel_display *display)
>>  {
>>  	const struct dram_info *dram_info = intel_dram_info(display);
>>  	const struct intel_soc_bw_params *soc_bw_params = get_soc_bw_params(display);
>> +	const struct intel_display_bw_params *display_bw_params = get_display_bw_params(display);

Feels like it gets increasingly weird to call all these functions
unconditionally when we bail out for !display right below.

BR,
Jani.

>>  
>>  	if (!HAS_DISPLAY(display))
>>  		return;
>> @@ -858,23 +879,12 @@ void intel_bw_init_hw(struct intel_display *display)
>>  
>>  	if (DISPLAY_VERx100(display) >= 1401 && display->platform.dgfx) {
>>  		xe2_hpd_get_bw_info(display, dram_info, soc_bw_params);
>> -	} else if (DISPLAY_VER(display) >= 14) {
>> -		tgl_get_bw_info(display, dram_info, soc_bw_params, &xelpdp_bw_params);
>>  	} else if (display->platform.dg2) {
>>  		dg2_get_bw_info(display);
>>  	} else if (DISPLAY_VER(display) >= 12) {
>> -		/*
>> -		 * RKL's SoC was based on ICL and the display, even though being
>> -		 * gen12, had changes to the memory interface to match gen11's,
>> -		 * consequently inheriting gen11's display-specific bandwidth
>> -		 * parameters.
>> -		 */
>> -		if (display->platform.rocketlake)
>> -			tgl_get_bw_info(display, dram_info, soc_bw_params, &gen11_bw_params);
>> -		else
>> -			tgl_get_bw_info(display, dram_info, soc_bw_params, &gen12_bw_params);
>> +		tgl_get_bw_info(display, dram_info, soc_bw_params, display_bw_params);
>>  	} else if (DISPLAY_VER(display) == 11) {
>> -		icl_get_bw_info(display, dram_info, soc_bw_params, &gen11_bw_params);
>> +		icl_get_bw_info(display, dram_info, soc_bw_params, display_bw_params);
>>  	}
>>  }
>>  
>> 
>> -- 
>> 2.53.0
>> 

-- 
Jani Nikula, Intel