Hi Alex,
Quoting "Deucher, Alexander" <Alexander.Deucher@xxxxxxx>:
-----Original Message-----
From: Gustavo A. R. Silva [mailto:garsilva@xxxxxxxxxxxxxx]
Sent: Wednesday, June 28, 2017 10:22 AM
To: Deucher, Alexander; Koenig, Christian; David Airlie
Cc: amd-gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-
kernel@xxxxxxxxxxxxxxx
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
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