Re: [PATCH 22/22] drm/i915: BDW: Pipe level CSC correction

["Sharma, Shashank" <shashank.sharma@intel.com>]

Regards
Shashank

On 10/13/2015 7:15 PM, Emil Velikov wrote:
> On 10 October 2015 at 06:34, Sharma, Shashank <shashank.sharma@intel.com> wrote:
>> On 10/10/2015 5:24 AM, Emil Velikov wrote:
>>>
>>> Hi Shashank,
>>>
>>> On 9 October 2015 at 20:29, Shashank Sharma <shashank.sharma@intel.com>
>>> wrote:
>>>>
>>>> BDW/SKL/BXT support Color Space Conversion (CSC) using a 3x3 matrix
>>>> that needs to be programmed into respective CSC registers.
>>>>
>>>> This patch does the following:
>>>> 1. Adds the core function to program CSC correction values for
>>>>      BDW/SKL/BXT platform
>>>> 2. Adds CSC correction macros/defines
>>>>
>>>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>>>> Signed-off-by: Kausal Malladi <kausalmalladi@gmail.com>
>>>> Signed-off-by: Kumar, Kiran S <kiran.s.kumar@intel.com>
>>>> ---
>>>>    drivers/gpu/drm/i915/i915_reg.h            |   7 ++
>>>>    drivers/gpu/drm/i915/intel_color_manager.c | 114
>>>> ++++++++++++++++++++++++++++-
>>>>    drivers/gpu/drm/i915/intel_color_manager.h |  12 ++-
>>>>    3 files changed, 129 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/i915_reg.h
>>>> b/drivers/gpu/drm/i915/i915_reg.h
>>>> index ed50f75..0e9d252 100644
>>>> --- a/drivers/gpu/drm/i915/i915_reg.h
>>>> +++ b/drivers/gpu/drm/i915/i915_reg.h
>>>> @@ -8085,4 +8085,11 @@ enum skl_disp_power_wells {
>>>>           (_PIPE3(pipe, PAL_PREC_GCMAX_A, PAL_PREC_GCMAX_B,
>>>> PAL_PREC_GCMAX_C))
>>>>
>>>>
>>>> +/* BDW CSC correction */
>>>> +#define CSC_COEFF_A                            0x49010
>>>> +#define CSC_COEFF_B                            0x49110
>>>> +#define CSC_COEFF_C                            0x49210
>>>> +#define _PIPE_CSC_COEFF(pipe) \
>>>> +       (_PIPE3(pipe, CSC_COEFF_A, CSC_COEFF_B, CSC_COEFF_C))
>>>> +
>>>>    #endif /* _I915_REG_H_ */
>>>> diff --git a/drivers/gpu/drm/i915/intel_color_manager.c
>>>> b/drivers/gpu/drm/i915/intel_color_manager.c
>>>> index e659382..0a6c00c 100644
>>>> --- a/drivers/gpu/drm/i915/intel_color_manager.c
>>>> +++ b/drivers/gpu/drm/i915/intel_color_manager.c
>>>> @@ -330,11 +330,119 @@ static int bdw_set_degamma(struct drm_device *dev,
>>>>           return 0;
>>>>    }
>>>>
>>>> -static s16 chv_prepare_csc_coeff(s64 csc_value)
>>>
>>> As mentioned previously, this should be part of the respective patch.
>>>
>> Agree. Looks like diff is messing up a bit. Will take care of this.
>>
>>>> +static uint32_t bdw_prepare_csc_coeff(int64_t coeff)
>>>> +{
>>>> +       uint32_t reg_val, ls_bit_pos, exponent_bits, sign_bit = 0;
>>>> +       int32_t mantissa;
>>>> +       uint64_t abs_coeff;
>>>> +
>>>> +       coeff = min_t(int64_t, coeff, BDW_CSC_COEFF_MAX_VAL);
>>>> +       coeff = max_t(int64_t, coeff, BDW_CSC_COEFF_MIN_VAL);
>>>> +
>>>> +       abs_coeff = abs(coeff);
>>>> +       if (abs_coeff < (BDW_CSC_COEFF_UNITY_VAL >> 3)) {
>>>> +               /* abs_coeff < 0.125 */
>>>> +               exponent_bits = 3;
>>>> +               ls_bit_pos = 19;
>>>> +       } else if (abs_coeff >= (BDW_CSC_COEFF_UNITY_VAL >> 3) &&
>>>> +               abs_coeff < (BDW_CSC_COEFF_UNITY_VAL >> 2)) {
>>>> +               /* abs_coeff >= 0.125 && val < 0.25 */
>>>> +               exponent_bits = 2;
>>>> +               ls_bit_pos = 20;
>>>> +       } else if (abs_coeff >= (BDW_CSC_COEFF_UNITY_VAL >> 2)
>>>> +               && abs_coeff < (BDW_CSC_COEFF_UNITY_VAL >> 1)) {
>>>> +               /* abs_coeff >= 0.25 && val < 0.5 */
>>>> +               exponent_bits = 1;
>>>> +               ls_bit_pos = 21;
>>>> +       } else if (abs_coeff >= (BDW_CSC_COEFF_UNITY_VAL >> 1)
>>>> +               && abs_coeff < BDW_CSC_COEFF_UNITY_VAL) {
>>>> +               /* abs_coeff >= 0.5 && val < 1.0 */
>>>> +               exponent_bits = 0;
>>>> +               ls_bit_pos = 22;
>>>> +       } else if (abs_coeff >= BDW_CSC_COEFF_UNITY_VAL &&
>>>> +               abs_coeff < (BDW_CSC_COEFF_UNITY_VAL << 1)) {
>>>> +               /* abs_coeff >= 1.0 && val < 2.0 */
>>>> +               exponent_bits = 7;
>>>> +               ls_bit_pos = 23;
>>>> +       } else {
>>>> +               /* abs_coeff >= 2.0 && val < 4.0 */
>>>> +               exponent_bits = 6;
>>>> +               ls_bit_pos = 24;
>>>> +       }
>>>> +
>>>> +       mantissa = GET_BITS_ROUNDOFF(abs_coeff, ls_bit_pos,
>>>> CSC_MAX_VALS);
>>>> +       if (coeff < 0) {
>>>> +               sign_bit = 1;
>>>> +               mantissa = -mantissa;
>>>> +               mantissa &= ((1 << CSC_MAX_VALS) - 1);
>>>
>>> I think there is a macro for this already ?
>>>
>> Thats for GAMMA_MAX, not for CSC_MAX. Or you mean the whole (1 <<
>> CSC_MAX_VALS -1) to be replaced with GET/SET bits ?
> What I mean is - the above looks exactly like the GET_BIT_MASK (which
> you introduced). Perhaps you can use it ?
>
Yes, Agree. but in later code review phase we realized that we dont even 
need this masking for mantissa. New patch set doesnt have this &ing, so 
we dont need this.
> Regards,
> Emil
>
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