On Wed, Jul 15, 2020 at 09:27:42PM -0700, Nathan Chancellor wrote:

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

Reviewed-by: Matt Roper matthew.d.roper@intel.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