[Intel-gfx] [PATCH v2 6/6] drm/i915: Do not do fb src adjustments for NV12

[Srinivas, Vidya]

> -----Original Message-----
> From: Maarten Lankhorst [mailto:maarten.lankhorst at linux.intel.com]
> Sent: Tuesday, April 17, 2018 1:21 PM
> To: Srinivas, Vidya <vidya.srinivas at intel.com>; Saarinen, Jani
> <jani.saarinen at intel.com>; intel-gfx at lists.freedesktop.org
> Cc: Kamath, Sunil <sunil.kamath at intel.com>
> Subject: Re: [PATCH v2 6/6] drm/i915: Do not do fb src adjustments for
> NV12
> 
> Op 17-04-18 om 09:38 schreef Srinivas, Vidya:
> >
> >> -----Original Message-----
> >> From: Maarten Lankhorst [mailto:maarten.lankhorst at linux.intel.com]
> >> Sent: Tuesday, April 17, 2018 12:55 PM
> >> To: Saarinen, Jani <jani.saarinen at intel.com>; Srinivas, Vidya
> >> <vidya.srinivas at intel.com>; intel-gfx-trybot at lists.freedesktop.org;
> >> intel- gfx at lists.freedesktop.org
> >> Cc: Kamath, Sunil <sunil.kamath at intel.com>
> >> Subject: Re: [PATCH v2 6/6] drm/i915: Do not do fb src adjustments
> >> for
> >> NV12
> >>
> >> Op 17-04-18 om 08:03 schreef Saarinen, Jani:
> >>> Lets move this to intel-gfx to get more eyes on it.
> >>>
> >>>> -----Original Message-----
> >>>> From: Srinivas, Vidya
> >>>> Sent: tiistai 17. huhtikuuta 2018 5.47
> >>>> To: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>;
> >>>> intel-gfx- trybot at lists.freedesktop.org
> >>>> Cc: Kamath, Sunil <sunil.kamath at intel.com>; Saarinen, Jani
> >>>> <jani.saarinen at intel.com>
> >>>> Subject: RE: [PATCH v2 6/6] drm/i915: Do not do fb src adjustments
> >>>> for NV12
> >>>>
> >>>>
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: Maarten Lankhorst [mailto:maarten.lankhorst at linux.intel.com]
> >>>>> Sent: Monday, April 16, 2018 8:00 PM
> >>>>> To: Srinivas, Vidya <vidya.srinivas at intel.com>; intel-gfx-
> >>>>> trybot at lists.freedesktop.org
> >>>>> Cc: Kamath, Sunil <sunil.kamath at intel.com>; Saarinen, Jani
> >>>>> <jani.saarinen at intel.com>
> >>>>> Subject: Re: [PATCH v2 6/6] drm/i915: Do not do fb src adjustments
> >>>>> for
> >>>>> NV12
> >>>>>
> >>>>> Hmm, more thought about src adjustments...
> >>>>>
> >>>>> Op 13-04-18 om 07:22 schreef Vidya Srinivas:
> >>>>>> We skip src trunction/adjustments for
> >>>>>> NV12 case and handle the sizes directly.
> >>>>>> Without this, pipe fifo underruns are seen on APL/KBL.
> >>>>>>
> >>>>>> v2: For NV12, making the src coordinates multiplier of 4
> >>>>>>
> >>>>>> Credits-to: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> >>>>>> Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
> >>>>>> ---
> >>>>>>  drivers/gpu/drm/i915/intel_display.c | 11 +++++++++++
> >>>>>> drivers/gpu/drm/i915/intel_sprite.c  | 15 +++++++++++++++
> >>>>>>  2 files changed, 26 insertions(+)
> >>>>>>
> >>>>>> diff --git a/drivers/gpu/drm/i915/intel_display.c
> >>>>>> b/drivers/gpu/drm/i915/intel_display.c
> >>>>>> index bc83f10..f64708f 100644
> >>>>>> --- a/drivers/gpu/drm/i915/intel_display.c
> >>>>>> +++ b/drivers/gpu/drm/i915/intel_display.c
> >>>>>> @@ -12978,6 +12978,10 @@ intel_check_primary_plane(struct
> >>>>> intel_plane *plane,
> >>>>>>  	bool can_position = false;
> >>>>>>  	int ret;
> >>>>>>  	uint32_t pixel_format = 0;
> >>>>>> +	struct drm_plane_state *plane_state = &state->base;
> >>>>>> +	struct drm_rect *src = &plane_state->src;
> >>>>>> +
> >>>>>> +	*src = drm_plane_state_src(plane_state);
> >>>>>>
> >>>>>>  	if (INTEL_GEN(dev_priv) >= 9) {
> >>>>>>  		/* use scaler when colorkey is not required */ @@ -
> 13001,6
> >>>>>> +13005,13 @@ intel_check_primary_plane(struct intel_plane
> *plane,
> >>>>>>  	if (!state->base.fb)
> >>>>>>  		return 0;
> >>>>>>
> >>>>>> +	if (pixel_format == DRM_FORMAT_NV12) {
> >>>>>> +		src->x1 = (((src->x1 >> 16)/4)*4) << 16;
> >>>>>> +		src->x2 = (((src->x2 >> 16)/4)*4) << 16;
> >>>>>> +		src->y1 = (((src->y1 >> 16)/4)*4) << 16;
> >>>>>> +		src->y2 = (((src->y2 >> 16)/4)*4) << 16;
> >>>>>> +	}
> >>>>> Lets reject non multiple of 4 coordinates for plane_state's src_x
> >>>>> and src_y, and before adjustment also reject non multiple of 4
> >>>>> src_w/src_h.fter that we can also reject clipping to the
> >>>>> right/bottom edge of the screen, if the pipe_src_w/h is not a
> >>>>> multiple of 4. That way an application trying to go beyond the screen.
> >>>> kms_plane_scaling and some other tests during execution generate
> >>>> lots of non mult of 4 buffer width/height. All these tests will
> >>>> show fail in the IGT BAT.
> >>>> In some cases, even thought the width and height will be multiple
> >>>> of
> >>>> 4 before the Adjustment (say our 16x16 buffer), this after
> >>>> adjustment becomes a 15 in intel_check_sprite_plane.
> >>>> This again would cause underrun. If we reject non multiple of 4s in
> >>>> our skl_update_scaler also, then even simple tests with 16x16 like
> >>>> rotation will fail due to it getting adjusted.
> >> Correct. This is why we fix up to a multiple of 4 after adjustments,
> >> and reject user passed coordinates before adjustment..
> >> plane_state->src_x/y/w/h is the property set by the user, while the
> >> plane_state->src rect is set and fixed up in the kernel.
> >>
> >> Rejecting clipping with positive coordinates if pipe_src w/h is not a
> >> multiple of 4 will fix a border case that shouldn't affect most
> >> modes, where the plane wouldn't extend to the crtc borders, which is
> what userspace wants there.
> >>
> > Thank you. Oh okay. Sorry. I thought we just reject and not do the fixing
> (mult of 4 later).
> > Sure, I will change the patch to also reject the coordinates before
> > adjustment (if its not Mult of 4).
> >
> >
> This can be done in skl_check_plane_surface, plane_state->src_{x,y,w,h}
> contains the user requested values.

Apologies for asking again. The adjustments are done in check_plane (both primary and sprite)
And towards the end of check_plane we call the skl_check_plane_surface.
I got your point that we will reject the user requested values if they are not multiple of 4.
But before we reach skl_check_plane_surface, they would’ve been adjusted/clipped etc
They wont remain user requested as is when they enter skl_check_plane_surface.
Please correct me if I am wrong or I am missing in understanding something here :(

I can add the add conversion to multiple of 4 in skl_check_plane_surface but rejection should be done before the clipping/adjustment
Or else, I move the entire clipping/adjustment code to skl_check_plane_surface?

Regards
Vidya
> 
> ~Maarten