Hi Alex, Quoting "Deucher, Alexander" <Alexander.Deucher at amd.com>: >> -----Original Message----- >> From: Gustavo A. R. Silva [mailto:garsilva at embeddedor.com] >> Sent: Wednesday, June 28, 2017 10:22 AM >> To: Deucher, Alexander; Koenig, Christian; David Airlie >> Cc: amd-gfx at lists.freedesktop.org; dri-devel at lists.freedesktop.org; linux- >> kernel at 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? --- 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
