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
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