Re: [PATCH 2/2] drm/i915: disable fbc due to Wa_16023588340

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Wed, Jun 26, 2024 at 05:17:41PM +0100, Matthew Auld wrote:
> On 26/06/2024 16:53, Rodrigo Vivi wrote:
> > On Wed, Jun 19, 2024 at 03:31:27PM +0100, Matthew Auld wrote:
> > > On BMG-G21 we need to disable fbc due to complications around the WA.
> > > 
> > > Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> > > Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>
> > > Cc: Matt Roper <matthew.d.roper@intel.com>
> > > Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> > > Cc: Vinod Govindapillai <vinod.govindapillai@intel.com>
> > > Cc: intel-gfx@lists.freedesktop.org
> > > ---
> > >   drivers/gpu/drm/i915/display/intel_display_wa.h |  8 ++++++++
> > >   drivers/gpu/drm/i915/display/intel_fbc.c        |  6 ++++++
> > >   drivers/gpu/drm/xe/Makefile                     |  4 +++-
> > >   drivers/gpu/drm/xe/display/xe_display_wa.c      | 16 ++++++++++++++++
> > >   4 files changed, 33 insertions(+), 1 deletion(-)
> > >   create mode 100644 drivers/gpu/drm/xe/display/xe_display_wa.c
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.h b/drivers/gpu/drm/i915/display/intel_display_wa.h
> > > index 63201d09852c..be644ab6ae00 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display_wa.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_display_wa.h
> > > @@ -6,8 +6,16 @@
> > >   #ifndef __INTEL_DISPLAY_WA_H__
> > >   #define __INTEL_DISPLAY_WA_H__
> > > +#include <linux/types.h>
> > > +
> > >   struct drm_i915_private;
> > >   void intel_display_wa_apply(struct drm_i915_private *i915);
> > > +#ifdef I915
> > > +static inline bool intel_display_needs_wa_16023588340(struct drm_i915_private *i915) { return false; }
> > > +#else
> > > +bool intel_display_needs_wa_16023588340(struct drm_i915_private *i915);
> > > +#endif
> > 
> > please avoid the ifdef I915 in new patches as we are trying to get away from that
> > in favor of a clean separation.
> 
> Can you please share an example for the best way to do that here, with clean
> separation?

hmmm... looking more to the patch now...
I don't believe that the WA/RTP rule from Xe should leak into i915 to be honest.

It looks like we are trending to a separate intel-display.ko that shouldn't depend
on driver's declarations like this.

Ideally I would also say that wa in the display code should relly on the 'D'
(display-id) of the GMD-ID. But I see that this 16023588340 is for the 'G' ip.
So, perhaps the display code should inspect the 'G' id from the device inside
display code?

Jani, thoughts on this?

> 
> I can add a new .c just for intel_display_needs_wa_16023588340 and move it
> there, which then avoids the ifdef I think, but that then adds an entirely
> new file just for this tiny stub. Unless I can dump it somewhere else?

One temporary workaround that I see without the ifdef I915 would be to
declare this function in i915_drv.h so in xe you add to the compat-i915-headers
instead of creating a new file there.

> 
> > 
> > > +
> > >   #endif
> > > diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> > > index 67116c9f1464..8488f82143a4 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> > > @@ -56,6 +56,7 @@
> > >   #include "intel_display_device.h"
> > >   #include "intel_display_trace.h"
> > >   #include "intel_display_types.h"
> > > +#include "intel_display_wa.h"
> > >   #include "intel_fbc.h"
> > >   #include "intel_fbc_regs.h"
> > >   #include "intel_frontbuffer.h"
> > > @@ -1237,6 +1238,11 @@ static int intel_fbc_check_plane(struct intel_atomic_state *state,
> > >   		return 0;
> > >   	}
> > > +	if (intel_display_needs_wa_16023588340(i915)) {
> > > +		plane_state->no_fbc_reason = "Wa_16023588340";
> > > +		return 0;
> > > +	}
> > > +
> > >   	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
> > >   	if (i915_vtd_active(i915) && (IS_SKYLAKE(i915) || IS_BROXTON(i915))) {
> > >   		plane_state->no_fbc_reason = "VT-d enabled";
> > > diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> > > index 0e16e5029081..f7521fd5db4c 100644
> > > --- a/drivers/gpu/drm/xe/Makefile
> > > +++ b/drivers/gpu/drm/xe/Makefile
> > > @@ -34,7 +34,8 @@ uses_generated_oob := \
> > >   	$(obj)/xe_ring_ops.o \
> > >   	$(obj)/xe_vm.o \
> > >   	$(obj)/xe_wa.o \
> > > -	$(obj)/xe_ttm_stolen_mgr.o
> > > +	$(obj)/xe_ttm_stolen_mgr.o \
> > > +	$(obj)/display/xe_display_wa.o \
> > >   $(uses_generated_oob): $(generated_oob)
> > > @@ -192,6 +193,7 @@ xe-$(CONFIG_DRM_XE_DISPLAY) += \
> > >   	display/xe_display.o \
> > >   	display/xe_display_misc.o \
> > >   	display/xe_display_rps.o \
> > > +	display/xe_display_wa.o \
> > >   	display/xe_dsb_buffer.o \
> > >   	display/xe_fb_pin.o \
> > >   	display/xe_hdcp_gsc.o \
> > > diff --git a/drivers/gpu/drm/xe/display/xe_display_wa.c b/drivers/gpu/drm/xe/display/xe_display_wa.c
> > > new file mode 100644
> > > index 000000000000..68e3d1959ad6
> > > --- /dev/null
> > > +++ b/drivers/gpu/drm/xe/display/xe_display_wa.c
> > > @@ -0,0 +1,16 @@
> > > +// SPDX-License-Identifier: MIT
> > > +/*
> > > + * Copyright © 2024 Intel Corporation
> > > + */
> > > +
> > > +#include "intel_display_wa.h"
> > > +
> > > +#include "xe_device.h"
> > > +#include "xe_wa.h"
> > > +
> > > +#include <generated/xe_wa_oob.h>
> > > +
> > > +bool intel_display_needs_wa_16023588340(struct drm_i915_private *i915)
> > > +{
> > > +	return XE_WA(xe_root_mmio_gt(i915), 16023588340);
> > > +}
> > > -- 
> > > 2.45.1
> > >