[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 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).