Re: [PATCH] drm/amd/display: Enable building new display engine with KCOV enabled

[Guenter Roeck]

On 7/14/22 09:29, Alex Deucher wrote:
> Applied.  Thanks!
>
> On Wed, Jul 13, 2022 at 4:03 PM Harry Wentland <harry.wentland@xxxxxxx> wrote:
> > On 2022-07-12 18:42, Guenter Roeck wrote:
> > > The new display engine uses floating point math, which is not supported
> > > by KCOV. Commit 9d1d02ff3678 ("drm/amd/display: Don't build DCN1 when kcov
> > > is enabled") tried to work around the problem by disabling
> > > CONFIG_DRM_AMD_DC_DCN if KCOV_INSTRUMENT_ALL and KCOV_ENABLE_COMPARISONS
> > > are enabled. The result is that KCOV can not be enabled on systems which
> > > require this display engine. A much simpler and less invasive solution is
> > > to disable KCOV selectively when compiling the display enagine while

"enagine". Outch.

Anyway, thanks for applying.

Guenter

> > > keeping it enabled for the rest of the kernel.
> > >
> > > Fixes: 9d1d02ff3678 ("drm/amd/display: Don't build DCN1 when kcov is enabled")
> > > Cc: Arnd Bergmann <arnd@xxxxxxxx>
> > > Cc: Leo Li <sunpeng.li@xxxxxxx>
> > > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> >
> > Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>
> >
> > Harry
> >
> > > ---
> > >   drivers/gpu/drm/amd/display/Kconfig     | 2 +-
> > >   drivers/gpu/drm/amd/display/dc/Makefile | 3 +++
> > >   2 files changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig
> > > index b4029c0d5d8c..96cbc87f7b6b 100644
> > > --- a/drivers/gpu/drm/amd/display/Kconfig
> > > +++ b/drivers/gpu/drm/amd/display/Kconfig
> > > @@ -6,7 +6,7 @@ config DRM_AMD_DC
> > >        bool "AMD DC - Enable new display engine"
> > >        default y
> > >        select SND_HDA_COMPONENT if SND_HDA_CORE
> > > -     select DRM_AMD_DC_DCN if (X86 || PPC64) && !(KCOV_INSTRUMENT_ALL && KCOV_ENABLE_COMPARISONS)
> > > +     select DRM_AMD_DC_DCN if (X86 || PPC64)
> > >        help
> > >          Choose this option if you want to use the new display engine
> > >          support for AMDGPU. This adds required support for Vega and
> > > diff --git a/drivers/gpu/drm/amd/display/dc/Makefile b/drivers/gpu/drm/amd/display/dc/Makefile
> > > index b4eca0236435..b801973749d2 100644
> > > --- a/drivers/gpu/drm/amd/display/dc/Makefile
> > > +++ b/drivers/gpu/drm/amd/display/dc/Makefile
> > > @@ -26,6 +26,9 @@
> > >   DC_LIBS = basics bios dml clk_mgr dce gpio irq link virtual
> > >
> > >   ifdef CONFIG_DRM_AMD_DC_DCN
> > > +
> > > +KCOV_INSTRUMENT := n
> > > +
> > >   DC_LIBS += dcn20
> > >   DC_LIBS += dsc
> > >   DC_LIBS += dcn10