| Message ID | 20170628180843.Horde.KKnryIaN7wki5B896j1w8Sa@gator4166.hostgator.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jun 28, 2017 at 7:08 PM, Gustavo A. R. Silva <garsilva@embeddedor.com> wrote: > Hi Alex, > > Quoting "Deucher, Alexander" <Alexander.Deucher@amd.com>: > >>> -----Original Message----- >>> From: Gustavo A. R. Silva [mailto:garsilva@embeddedor.com] >>> Sent: Wednesday, June 28, 2017 10:22 AM >>> To: Deucher, Alexander; Koenig, Christian; David Airlie >>> Cc: amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; >>> linux- >>> kernel@vger.kernel.org >>> Subject: [gpu-drm-radeon] question about potential dead code in >>> vce_v2_0_enable_mgcg() >>> >>> >>> Hello everybody, >>> >>> While looking into Coverity ID 1198635 I ran into the following piece >>> of code at drivers/gpu/drm/radeon/vce_v2_0.c:107: >>> >>> 107void vce_v2_0_enable_mgcg(struct radeon_device *rdev, bool enable) >>> 108{ >>> 109 bool sw_cg = false; >>> 110 >>> 111 if (enable && (rdev->cg_flags & >>> RADEON_CG_SUPPORT_VCE_MGCG)) { >>> 112 if (sw_cg) >>> 113 vce_v2_0_set_sw_cg(rdev, true); >>> 114 else >>> 115 vce_v2_0_set_dyn_cg(rdev, true); >>> 116 } else { >>> 117 vce_v2_0_disable_cg(rdev); >>> 118 >>> 119 if (sw_cg) >>> 120 vce_v2_0_set_sw_cg(rdev, false); >>> 121 else >>> 122 vce_v2_0_set_dyn_cg(rdev, false); >>> 123 } >>> 124} >>> >>> The issue here is that local variable sw_cg is never updated again >>> after its initialization; which cause some code to be logically dead. >>> >>> My question here is if such variable is there for testing purposes or >>> if it is a sort of an old code leftover that should be removed? >>> >>> In any case I can send a patch to add a comment or remove the dead code. >>> >>> I'd really appreciate any comments on this. >> >> >> I wanted to leave the code in for debugging if we ran into problems with >> dynamic clockgating. >> > > Do you mind if I send a patch to add such comment and make it clear the > purpose of that variable? Sure. Thanks. Alex > > --- a/drivers/gpu/drm/radeon/vce_v2_0.c > +++ b/drivers/gpu/drm/radeon/vce_v2_0.c > @@ -104,6 +104,10 @@ static void vce_v2_0_disable_cg(struct radeon_device > *rdev) > WREG32(VCE_CGTT_CLK_OVERRIDE, 7); > } > > +/* > + * Local variable sw_cg is used for debugging purposes, in case we > + * ran into problems with dynamic clock gating. Don't remove it. > + */ > void vce_v2_0_enable_mgcg(struct radeon_device *rdev, bool enable) > { > bool sw_cg = false; > > > Thanks for clarifying! > -- > Gustavo A. R. Silva > > > > > > > _______________________________________________ > amd-gfx mailing list > amd-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx
On Thu, Jun 29, 2017 at 1:38 PM, Gustavo A. R. Silva <garsilva@embeddedor.com> wrote: > Add function header comment to make it clear that local variable sw_cg > is used for debugging and it should not be removed. > > Addresses-Coverity-ID: 1198635 > Cc: Alex Deucher <alexdeucher@gmail.com> > Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Applied. thanks! Alex > --- > drivers/gpu/drm/radeon/vce_v2_0.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/gpu/drm/radeon/vce_v2_0.c b/drivers/gpu/drm/radeon/vce_v2_0.c > index fce2144..b0a43b6 100644 > --- a/drivers/gpu/drm/radeon/vce_v2_0.c > +++ b/drivers/gpu/drm/radeon/vce_v2_0.c > @@ -104,6 +104,10 @@ static void vce_v2_0_disable_cg(struct radeon_device *rdev) > WREG32(VCE_CGTT_CLK_OVERRIDE, 7); > } > > +/* > + * Local variable sw_cg is used for debugging purposes, in case we > + * ran into problems with dynamic clock gating. Don't remove it. > + */ > void vce_v2_0_enable_mgcg(struct radeon_device *rdev, bool enable) > { > bool sw_cg = false; > -- > 2.5.0 >
Quoting Alex Deucher <alexdeucher@gmail.com>: > On Thu, Jun 29, 2017 at 1:38 PM, Gustavo A. R. Silva > <garsilva@embeddedor.com> wrote: >> Add function header comment to make it clear that local variable sw_cg >> is used for debugging and it should not be removed. >> >> Addresses-Coverity-ID: 1198635 >> Cc: Alex Deucher <alexdeucher@gmail.com> >> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> > > Applied. thanks! > Great, glad to help :) Thanks -- Gustavo A. R. Silva
--- a/drivers/gpu/drm/radeon/vce_v2_0.c +++ b/drivers/gpu/drm/radeon/vce_v2_0.c @@ -104,6 +104,10 @@ static void vce_v2_0_disable_cg(struct radeon_device *rdev) WREG32(VCE_CGTT_CLK_OVERRIDE, 7); } +/* + * Local variable sw_cg is used for debugging purposes, in case we + * ran into problems with dynamic clock gating. Don't remove it. + */ void vce_v2_0_enable_mgcg(struct radeon_device *rdev, bool enable) {