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From: Zhouyi Zhou <zhouzhouyi@gmail.com>
Date: Tue, 28 May 2024 09:36:58 +0800
Message-ID: <CAABZP2zGfhcYrn6UOhmkXEgtCAPLcN7bgCdbzAi1r+aNrToHKQ@mail.gmail.com>
Subject: Re: [PATCH] drm/radeon/r100: enhance error handling in r100_cp_init_microcode
To: =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>
Cc: alexander.deucher@amd.com, Xinhui.Pan@amd.com, airlied@gmail.com, 
	daniel@ffwll.ch, chris@chrisdown.name, amd-gfx@lists.freedesktop.org, 
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, 
	rcu@vger.kernel.org, lance@osuosl.org
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Thanks for reviewing the patch

On Mon, May 27, 2024 at 3:58=E2=80=AFPM Christian K=C3=B6nig
<christian.koenig@amd.com> wrote:
>
> Am 27.05.24 um 03:20 schrieb Zhouyi Zhou:
> > In r100_cp_init_microcode, if rdev->family don't match any of
> > if statement,  fw_name will be NULL, which will cause
> > gcc (11.4.0 powerpc64le-linux-gnu) complain:
> >
> > In function =E2=80=98r100_cp_init_microcode=E2=80=99,
> >      inlined from =E2=80=98r100_cp_init=E2=80=99 at drivers/gpu/drm/rad=
eon/r100.c:1136:7:
> > ./include/linux/printk.h:457:44: warning: =E2=80=98%s=E2=80=99 directiv=
e argument is null [-Wformat-overflow=3D]
> >    457 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__V=
A_ARGS__)
> >
> > Above warning is emitted during the rcutorture test in
> > in PPC VM of Opensource Lab of Oregon State Univerisity.
> >
> > Enhance error handling in r100_cp_init_microcode, let r100_cp_init_micr=
ocode
> > return with -EINVAL when none of chip families is matched.
> >
> > Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
>
> > ---
> >   drivers/gpu/drm/radeon/r100.c | 7 +++++++
> >   1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r10=
0.c
> > index 0b1e19345f43..4f8a1bdd9365 100644
> > --- a/drivers/gpu/drm/radeon/r100.c
> > +++ b/drivers/gpu/drm/radeon/r100.c
> > @@ -1055,6 +1055,11 @@ static int r100_cp_init_microcode(struct radeon_=
device *rdev)
> >                  (rdev->family =3D=3D CHIP_RV570)) {
> >               DRM_INFO("Loading R500 Microcode\n");
> >               fw_name =3D FIRMWARE_R520;
> > +     } else {
> > +             pr_err("radeon_cp: Failed to load firmware \"%d\"\n",
> > +                     rdev->family);
> > +             err =3D -EINVAL;
> > +             goto out;
> >       }
> >
> >       err =3D request_firmware(&rdev->me_fw, fw_name, rdev->dev);
> > @@ -1067,6 +1072,8 @@ static int r100_cp_init_microcode(struct radeon_d=
evice *rdev)
> >               release_firmware(rdev->me_fw);
> >               rdev->me_fw =3D NULL;
> >       }
> > +
> > +out:
>
> That looks superfluous, just return -EINVAL directly in the else case abo=
ve.
>
> Apart from that this is for ~15year old hardware. I'm a bit reluctant
> adding code for something that old even when this change here looks
> harmless.
>
> Is there a plan to complain about that in an automated checker? If yes
> then the change is probably justified, if no then I would rather not do i=
t.
The warning is emitted when I invoke following commands in ubuntu
22.04 (ppc64le)
linux$make allmodconfig
linux$make drivers/gpu/drm/radeon/r100.o (a quick alternative to 'make -j$n=
proc)

But everything is OK when I invoke following commands in ubuntu 22.04 (ppc6=
4le)
linux$make allmodconfig LLVM=3D1
linux$make drivers/gpu/drm/radeon/r100.o LLVM=3D1

And I can't reproduce the warning in the x86 environment, so I guess
this phenomenon
is toolchain related ;-)

Thanks again
Regards,
Zhouyi
>
> Regards,
> Christian.
>
> >       return err;
> >   }
> >
>