Re: [Intel-gfx] [PATCH v5 16/19] uapi/drm/dg2: Introduce format modifier for DG2 clear color

[Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>]

On 15.2.2022 17.02, Chery, Nanley G wrote:
> 
> 
>> -----Original Message-----
>> From: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
>> Sent: Tuesday, February 15, 2022 6:56 AM
>> To: Nanley Chery <nanleychery@gmail.com>; C, Ramalingam
>> <ramalingam.c@intel.com>
>> Cc: intel-gfx <intel-gfx@lists.freedesktop.org>; Chery, Nanley G
>> <nanley.g.chery@intel.com>; Auld, Matthew <matthew.auld@intel.com>; dri-
>> devel <dri-devel@lists.freedesktop.org>
>> Subject: Re: [Intel-gfx] [PATCH v5 16/19] uapi/drm/dg2: Introduce format
>> modifier for DG2 clear color
>>
>> On 12.2.2022 3.19, Nanley Chery wrote:
>>> On Tue, Feb 1, 2022 at 2:42 AM Ramalingam C <ramalingam.c@intel.com>
>> wrote:
>>>>
>>>> From: Mika Kahola <mika.kahola@intel.com>
>>>>
>>>> DG2 clear color render compression uses Tile4 layout. Therefore, we
>>>> need to define a new format modifier for uAPI to support clear color
>> rendering.
>>>>
>>>> v2:
>>>>     Display version is fixed. [Imre]
>>>>     KDoc is enhanced for cc modifier. [Nanley & Lionel]
>>>>
>>>> Signed-off-by: Mika Kahola <mika.kahola@intel.com>
>>>> cc: Anshuman Gupta <anshuman.gupta@intel.com>
>>>> Signed-off-by: Juha-Pekka Heikkilä <juha-pekka.heikkila@intel.com>
>>>> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
>>>> ---
>>>>    drivers/gpu/drm/i915/display/intel_fb.c            |  8 ++++++++
>>>>    drivers/gpu/drm/i915/display/skl_universal_plane.c |  9 ++++++++-
>>>>    include/uapi/drm/drm_fourcc.h                      | 10 ++++++++++
>>>>    3 files changed, 26 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_fb.c
>>>> b/drivers/gpu/drm/i915/display/intel_fb.c
>>>> index 4d4d01963f15..3df6ef5ffec5 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_fb.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_fb.c
>>>> @@ -144,6 +144,12 @@ static const struct intel_modifier_desc
>> intel_modifiers[] = {
>>>>                   .modifier = I915_FORMAT_MOD_4_TILED_DG2_MC_CCS,
>>>>                   .display_ver = { 13, 13 },
>>>>                   .plane_caps = INTEL_PLANE_CAP_TILING_4 |
>>>> INTEL_PLANE_CAP_CCS_MC,
>>>> +       }, {
>>>> +               .modifier = I915_FORMAT_MOD_4_TILED_DG2_RC_CCS_CC,
>>>> +               .display_ver = { 13, 13 },
>>>> +               .plane_caps = INTEL_PLANE_CAP_TILING_4 |
>>>> + INTEL_PLANE_CAP_CCS_RC_CC,
>>>> +
>>>> +               .ccs.cc_planes = BIT(1),
>>>>           }, {
>>>>                   .modifier = I915_FORMAT_MOD_4_TILED_DG2_RC_CCS,
>>>>                   .display_ver = { 13, 13 }, @@ -559,6 +565,7 @@
>>>> intel_tile_width_bytes(const struct drm_framebuffer *fb, int color_plane)
>>>>                   else
>>>>                           return 512;
>>>>           case I915_FORMAT_MOD_4_TILED_DG2_RC_CCS:
>>>> +       case I915_FORMAT_MOD_4_TILED_DG2_RC_CCS_CC:
>>>>           case I915_FORMAT_MOD_4_TILED_DG2_MC_CCS:
>>>>           case I915_FORMAT_MOD_4_TILED:
>>>>                   /*
>>>> @@ -763,6 +770,7 @@ unsigned int intel_surf_alignment(const struct
>> drm_framebuffer *fb,
>>>>           case I915_FORMAT_MOD_Yf_TILED:
>>>>                   return 1 * 1024 * 1024;
>>>>           case I915_FORMAT_MOD_4_TILED_DG2_RC_CCS:
>>>> +       case I915_FORMAT_MOD_4_TILED_DG2_RC_CCS_CC:
>>>>           case I915_FORMAT_MOD_4_TILED_DG2_MC_CCS:
>>>>                   return 16 * 1024;
>>>>           default:
>>>> diff --git a/drivers/gpu/drm/i915/display/skl_universal_plane.c
>>>> b/drivers/gpu/drm/i915/display/skl_universal_plane.c
>>>> index c38ae0876c15..b4dced1907c5 100644
>>>> --- a/drivers/gpu/drm/i915/display/skl_universal_plane.c
>>>> +++ b/drivers/gpu/drm/i915/display/skl_universal_plane.c
>>>> @@ -772,6 +772,8 @@ static u32 skl_plane_ctl_tiling(u64 fb_modifier)
>>>>                   return PLANE_CTL_TILED_4 |
>>>>                           PLANE_CTL_MEDIA_DECOMPRESSION_ENABLE |
>>>>                           PLANE_CTL_CLEAR_COLOR_DISABLE;
>>>> +       case I915_FORMAT_MOD_4_TILED_DG2_RC_CCS_CC:
>>>> +               return PLANE_CTL_TILED_4 |
>>>> + PLANE_CTL_RENDER_DECOMPRESSION_ENABLE;
>>>>           case I915_FORMAT_MOD_Y_TILED_CCS:
>>>>           case I915_FORMAT_MOD_Y_TILED_GEN12_RC_CCS_CC:
>>>>                   return PLANE_CTL_TILED_Y |
>>>> PLANE_CTL_RENDER_DECOMPRESSION_ENABLE;
>>>> @@ -2358,10 +2360,15 @@ skl_get_initial_plane_config(struct intel_crtc
>> *crtc,
>>>>                   break;
>>>>           case PLANE_CTL_TILED_YF: /* aka PLANE_CTL_TILED_4 on XE_LPD+ */
>>>>                   if (HAS_4TILE(dev_priv)) {
>>>> -                       if (val & PLANE_CTL_RENDER_DECOMPRESSION_ENABLE)
>>>> +                       u32 rc_mask = PLANE_CTL_RENDER_DECOMPRESSION_ENABLE |
>>>> +                                     PLANE_CTL_CLEAR_COLOR_DISABLE;
>>>> +
>>>> +                       if ((val & rc_mask) == rc_mask)
>>>>                                   fb->modifier = I915_FORMAT_MOD_4_TILED_DG2_RC_CCS;
>>>>                           else if (val & PLANE_CTL_MEDIA_DECOMPRESSION_ENABLE)
>>>>                                   fb->modifier =
>>>> I915_FORMAT_MOD_4_TILED_DG2_MC_CCS;
>>>> +                       else if (val & PLANE_CTL_RENDER_DECOMPRESSION_ENABLE)
>>>> +                               fb->modifier =
>>>> + I915_FORMAT_MOD_4_TILED_DG2_RC_CCS_CC;
>>>>                           else
>>>>                                   fb->modifier = I915_FORMAT_MOD_4_TILED;
>>>>                   } else {
>>>> diff --git a/include/uapi/drm/drm_fourcc.h
>>>> b/include/uapi/drm/drm_fourcc.h index b8fb7b44c03c..697614ea4b84
>>>> 100644
>>>> --- a/include/uapi/drm/drm_fourcc.h
>>>> +++ b/include/uapi/drm/drm_fourcc.h
>>>> @@ -605,6 +605,16 @@ extern "C" {
>>>>     */
>>>>    #define I915_FORMAT_MOD_4_TILED_DG2_MC_CCS
>> fourcc_mod_code(INTEL,
>>>> 11)
>>>>
>>>> +/*
>>>> + * Intel color control surfaces (CCS) for DG2 clear color render compression.
>>>> + *
>>>> + * DG2 uses a unified compression format for clear color render
>> compression.
>>>
>>> What's unified about DG2's compression format? If this doesn't affect
>>> the layout, maybe we should drop this sentence.
>>>
>>>> + * The general layout is a tiled layout using 4Kb tiles i.e. Tile4 layout.
>>>> + *
>>>
>>> This also needs a pitch aligned to four tiles, right? I think we can
>>> save some effort by referencing the DG2_RC_CCS modifier here.
>>>
>>>> + * Fast clear color value expected by HW is located in fb at offset
>>>> + 0 of plane#1
>>>
>>> Why is the expected offset hardcoded to 0 instead of relying on the
>>> offset provided by the modifier API? This looks like a bug.
>>
>> Hi Nanley,
>>
>> can you elaborate a bit, which offset from modifier API that applies to cc surface?
>>
> 
> Hi Juha-Pekka,
> 
> On the kernel-side of things, I'm thinking of drm_mode_fb_cmd2::offsets[1].
> 

Hi Nanley,

this offset is coming from userspace on creation of framebuffer, at that 
moment from userspace caller can point to offset of desire. Normally 
offset[0] is set at 0 and then offset[n] at plane n start which is not 
stated to have to be exactly after plane n-1 end. Or did I misunderstand 
what you meant?

For cc plane this offset likely will not be zero anyway and caller can 
move it as see fit to have cc plane (plane[1]) location[0] at place 
where wanted to have it.

/Juha-Pekka

> 
>>>
>>> We should probably give some info about the relevant fields in the
>>> fast clear plane (like what's done in the GEN12_RC_CCS_CC modifier).
>>
>> agree, that's totally missing here.
>>
>> /Juha-Pekka
>>
>>>
>>>> + */
>>>> +#define I915_FORMAT_MOD_4_TILED_DG2_RC_CCS_CC
>> fourcc_mod_code(INTEL,
>>>> +12)
>>>> +
>>>>    /*
>>>>     * Tiled, NV12MT, grouped in 64 (pixels) x 32 (lines) -sized macroblocks
>>>>     *
>>>> --
>>>> 2.20.1
>>>>
>