[Intel-gfx] [PATCH] drm/i915/dmc: Use RUNTIME_INFO->stp for DMC

[Lucas De Marchi]

On Wed, Jun 30, 2021 at 05:17:52PM -0700, Lucas De Marchi wrote:
>On Wed, Jun 30, 2021 at 05:15:00PM -0700, Jose Souza wrote:
>>On Wed, 2021-06-30 at 17:01 -0700, Lucas De Marchi wrote:
>>>Typo: RUNTIME_INFO->stp
>>>
>>>On Wed, Jun 30, 2021 at 04:06:24PM -0700, Anusha Srivatsa wrote:
>>>> On the dmc side,we maintain a lookup table with different display
>>>> stepping-substepping combinations.
>>>>
>>>> Instead of adding new table for every new platform, lets ues
>>>> the stepping info from RUNTIME_INFO(dev_priv)->step
>>>> Adding the helper intel_get_display_step().
>>>>
>>>> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>>>> Signed-off-by: Anusha Srivatsa <anusha.srivatsa at intel.com>
>>>> ---
>>>> drivers/gpu/drm/i915/display/intel_dmc.c | 49 ++++++++++++++++++++++--
>>>> 1 file changed, 45 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
>>>> index f8789d4543bf..c7ff7ff3f412 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_dmc.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_dmc.c
>>>> @@ -266,14 +266,55 @@ static const struct stepping_info icl_stepping_info[] = {
>>>> };
>>>>
>>>> static const struct stepping_info no_stepping_info = { '*', '*' };
>>>> +struct stepping_info *display_step;
>>>> +
>>>> +static struct stepping_info *
>>>> +intel_get_display_stepping(struct intel_step_info step)
>>>> +{
>>>> +
>>>> +	switch (step.display_step) {
>>>> +	case STEP_A0:
>>>> +		display_step->stepping = 'A';
>>>> +		display_step->substepping = '0';
>>>> +		break;
>>>> +	case STEP_A2:
>>>> +		display_step->stepping = 'A';
>>>> +		display_step->substepping = '2';
>>>> +		break;
>>>> +	case STEP_B0:
>>>> +		display_step->stepping = 'B';
>>>> +		display_step->substepping = '0';
>>>> +		break;
>>>> +	case STEP_B1:
>>>> +		display_step->stepping = 'B';
>>>> +		display_step->substepping = '1';
>>>> +		break;
>>>> +	case STEP_C0:
>>>> +		display_step->stepping = 'C';
>>>> +		display_step->substepping = '0';
>>>> +		break;
>>>> +	case STEP_D0:
>>>> +		display_step->stepping = 'D';
>>>> +		display_step->substepping = '0';
>>>> +		break;
>>>> +	default:
>>>> +		display_step->stepping = '*';
>>>> +		display_step->substepping = '*';
>>>> +		break;
>>>> +	}
>>>
>>>
>>>"crazy" idea that would avoid this type of conversion:
>>>changing the step enum to be:
>>>
>>>
>>>#define make_step(letter, num) (int)(((letter) << 8 ) | (num))
>>>
>>>STEP_A0 = make_step('A', '0'),
>>>STEP_A1 = make_step('A', '1'),
>>
>>Looks a good idea to me, we could also keep it u8 using 4bits for each if there is memory concerns.
>
>humn... indeed. Not much a concern actually, but not having to change
>additional code is already a good thing.
>
>
>I hope no stepping goes beyond Z9 :)

I take that out. Even if we would do (number - 'A'), there is not enough
room in 4bits to handle until Z. In fact we could go only until P8 - so
if we are going that route we will need to have some extra build checks
that we don't go beyond that.

Lucas De Marchi