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

["Chery, Nanley G" <nanley.g.chery@intel.com>]

> -----Original Message-----
> From: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
> Sent: Tuesday, February 15, 2022 8:15 AM
> To: Chery, Nanley G <nanley.g.chery@intel.com>; Nanley Chery
> <nanleychery@gmail.com>; C, Ramalingam <ramalingam.c@intel.com>
> Cc: intel-gfx <intel-gfx@lists.freedesktop.org>; 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 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?
> 

Perhaps, at least, I'm not sure what you're meaning to say. This modifier description
seems to say that the drm_mode_fb_cmd2::offsets value for the clear color plane
must be zero. Are you saying that it's correct? This doesn't match the 
GEN12_RC_CCS_CC behavior and doesn't match mesa's expectations.

-Nanley

> 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
> >>>>
> >