Re: [v7, 01/16] drm: Add Enhanced Gamma LUT precision structure

Shankar, Uma
2019-08-14T14:29:57Z

>-----Original Message-----
>From: james qian wang (Arm Technology China) [mailto:james.qian.wang@arm.com]
>Sent: Tuesday, August 13, 2019 3:12 PM
>To: Shankar, Uma <uma.shankar@intel.com>
>Cc: intel-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; Syrjala, Ville
><ville.syrjala@intel.com>; emil.l.velikov@gmail.com; Lankhorst, Maarten
><maarten.lankhorst@intel.com>; nd <nd@arm.com>
>Subject: Re: [v7,01/16] drm: Add Enhanced Gamma LUT precision structure
>
>On Fri, Mar 29, 2019 at 01:45:59AM +0530, Uma Shankar wrote:
>> Existing LUT precision structure is having only 16 bit precision. This
>> is not enough for upcoming enhanced hardwares and advance usecases
>> like HDR processing. Hence added a new structure with 32 bit precision
>> values. Also added the code, for extracting the same from values
>> passed from userspace.
>>
>> v4: Rebase
>>
>> v5: Relocated the helper function to drm_color_mgmt.c. Declared the
>> same in a header file (Alexandru Gheorghe)
>>
>> v6: Enhanced gamma lut structure to take U32.32 format as input.
>> This is needed for HDR usecase which require higher precision.
>>
>> v7: Addressed Maarten's review comments and fixed the calculation.
>>
>> Signed-off-by: Uma Shankar <uma.shankar@intel.com>
>> Reviewed-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
>
>Hi Uma
>
>When can we merge these plane color-mgmt support into upstream ?
>or can we merge the DRM-CORE part patches firstly?

Hi James,
I will refresh this series by early next week. We will try to prioritize this development and speed
up with merge.

Regards,
Uma Shankar

>thanks
>james
>
>> ---
>> drivers/gpu/drm/drm_color_mgmt.c | 20 ++++++++++++++++++++
>> include/drm/drm_color_mgmt.h | 1 +
>> include/uapi/drm/drm_mode.h | 15 +++++++++++++++
>> 3 files changed, 36 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_color_mgmt.c
>> b/drivers/gpu/drm/drm_color_mgmt.c
>> index d5d34d0..79ff874 100644
>> --- a/drivers/gpu/drm/drm_color_mgmt.c
>> +++ b/drivers/gpu/drm/drm_color_mgmt.c
>> @@ -128,6 +128,26 @@ uint32_t drm_color_lut_extract(uint32_t
>> user_input, uint32_t bit_precision) }
>> EXPORT_SYMBOL(drm_color_lut_extract);
>>
>> +/*
>> + * Added to accommodate enhanced LUT precision.
>> + * Max LUT precision is 32 bits.
>> + */
>> +u64 drm_color_lut_extract_ext(u64 user_input, u32 bit_precision) {
>> + u64 val = user_input & 0xffffffff;
>> + u32 max = 0xffffffff >> (32 - bit_precision);
>> +
>> + /* Round only if we're not using full precision. */
>> + if (bit_precision < 32) {
>> + val += 1UL << (32 - bit_precision - 1);
>> + val >>= 32 - bit_precision;
>> + }
>> +
>> + return ((user_input & 0xffffffff00000000) |
>> + clamp_val(val, 0, max));
>> +}
>> +EXPORT_SYMBOL(drm_color_lut_extract_ext);
>> +
>> /**
>> * drm_crtc_enable_color_mgmt - enable color management properties
>> * @crtc: DRM CRTC
>> diff --git a/include/drm/drm_color_mgmt.h
>> b/include/drm/drm_color_mgmt.h index d1c662d..c9d2746 100644
>> --- a/include/drm/drm_color_mgmt.h
>> +++ b/include/drm/drm_color_mgmt.h
>> @@ -30,6 +30,7 @@
>> struct drm_plane;
>>
>> uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t
>> bit_precision);
>> +u64 drm_color_lut_extract_ext(u64 user_input, u32 bit_precision);
>>
>> void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
>> uint degamma_lut_size,
>> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
>> index 09d7296..ca81410 100644
>> --- a/include/uapi/drm/drm_mode.h
>> +++ b/include/uapi/drm/drm_mode.h
>> @@ -629,6 +629,21 @@ struct drm_color_lut {
>> __u16 reserved;
>> };
>>
>> +/*
>> + * Creating 64 bit palette entries for better data
>> + * precision. This will be required for HDR and
>> + * similar color processing usecases.
>> + */
>> +struct drm_color_lut_ext {
>> + /*
>> + * Data is U32.32 fixed point format.
>> + */
>> + __u64 red;
>> + __u64 green;
>> + __u64 blue;
>> + __u64 reserved;
>> +};
>> +
>> #define DRM_MODE_PAGE_FLIP_EVENT 0x01 #define
>> DRM_MODE_PAGE_FLIP_ASYNC 0x02 #define
>> DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE 0x4