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* [Intel-gfx] [PATCH] drm/i915/display: Ensure that ret is always initialized in icl_combo_phy_verify_state
@ 2020-07-16  4:27 Nathan Chancellor
  2020-07-16  4:44 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for " Patchwork
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Nathan Chancellor @ 2020-07-16  4:27 UTC (permalink / raw)
  To: Jani Nikula, Joonas Lahtinen, Rodrigo Vivi
  Cc: intel-gfx, linux-kernel, dri-devel, clang-built-linux, Nathan Chancellor

Clang warns:

drivers/gpu/drm/i915/display/intel_combo_phy.c:268:3: warning: variable
'ret' is uninitialized when used here [-Wuninitialized]
                ret &= check_phy_reg(dev_priv, phy, ICL_PORT_TX_DW8_LN0(phy),
                ^~~
drivers/gpu/drm/i915/display/intel_combo_phy.c:261:10: note: initialize
the variable 'ret' to silence this warning
        bool ret;
                ^
                 = 0
1 warning generated.

In practice, the bug this warning appears to be concerned with would not
actually matter because ret gets initialized to the return value of
cnl_verify_procmon_ref_values. However, that does appear to be a bug
since it means the first hunk of the patch this fixes won't actually do
anything (since the values of check_phy_reg won't factor into the final
ret value). Initialize ret to true then make all of the assignments a
bitwise AND with itself so that the function always does what it should
do.

Fixes: 239bef676d8e ("drm/i915/display: Implement new combo phy initialization step")
Link: https://github.com/ClangBuiltLinux/linux/issues/1094
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 drivers/gpu/drm/i915/display/intel_combo_phy.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_combo_phy.c b/drivers/gpu/drm/i915/display/intel_combo_phy.c
index eccaa79cb4a9..a4b8aa6d0a9e 100644
--- a/drivers/gpu/drm/i915/display/intel_combo_phy.c
+++ b/drivers/gpu/drm/i915/display/intel_combo_phy.c
@@ -258,7 +258,7 @@ static bool phy_is_master(struct drm_i915_private *dev_priv, enum phy phy)
 static bool icl_combo_phy_verify_state(struct drm_i915_private *dev_priv,
 				       enum phy phy)
 {
-	bool ret;
+	bool ret = true;
 	u32 expected_val = 0;
 
 	if (!icl_combo_phy_enabled(dev_priv, phy))
@@ -276,7 +276,7 @@ static bool icl_combo_phy_verify_state(struct drm_i915_private *dev_priv,
 				     DCC_MODE_SELECT_CONTINUOSLY);
 	}
 
-	ret = cnl_verify_procmon_ref_values(dev_priv, phy);
+	ret &= cnl_verify_procmon_ref_values(dev_priv, phy);
 
 	if (phy_is_master(dev_priv, phy)) {
 		ret &= check_phy_reg(dev_priv, phy, ICL_PORT_COMP_DW8(phy),

base-commit: ca0e494af5edb59002665bf12871e94b4163a257
-- 
2.28.0.rc0

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^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-07-28  4:08 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-16  4:27 [Intel-gfx] [PATCH] drm/i915/display: Ensure that ret is always initialized in icl_combo_phy_verify_state Nathan Chancellor
2020-07-16  4:44 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for " Patchwork
2020-07-16  5:06 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2020-07-28  1:47   ` Souza, Jose
2020-07-28  4:08     ` Nathan Chancellor
2020-07-16  5:31 ` [Intel-gfx] [PATCH] " Matt Roper

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