On Thu, Oct 14, 2021 at 02:21:43PM -0700, Nick Desaulniers wrote:

On Thu, Oct 14, 2021 at 2:19 PM Nathan Chancellor nathan@kernel.org wrote:

...

A new warning in clang points out a place in this file where a bitwise OR is being used with boolean types:

drivers/gpu/drm/i915/intel_pm.c:3066:12: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical] changed = ilk_increase_wm_latency(dev_priv, dev_priv->wm.pri_latency, 12) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This construct is intentional, as it allows every one of the calls to ilk_increase_wm_latency() to occur (instead of short circuiting with logical OR) while still caring about the result of each call.

To make this clearer to the compiler, use the '|=' operator to assign the result of each ilk_increase_wm_latency() call to changed, which keeps the meaning of the code the same but makes it obvious that every one of these calls is expected to happen.

Sure, why not.

...

Link: https://github.com/ClangBuiltLinux/linux/issues/1473 Reported-by: Nick Desaulniers ndesaulniers@google.com

Thanks for the patch! Suggested-by: Dávid Bolvanský david.bolvansky@gmail.com Reviewed-by: Nick Desaulniers ndesaulniers@google.com

Thanks for the patch+review. Applied to drm-intel-next.

...

Signed-off-by: Nathan Chancellor nathan@kernel.org

drivers/gpu/drm/i915/intel_pm.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index f90fe39cf8ca..aaa3a0998e4c 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -3050,9 +3050,9 @@ static void snb_wm_latency_quirk(struct drm_i915_private *dev_priv) * The BIOS provided WM memory latency values are often * inadequate for high resolution displays. Adjust them. */

•   changed = ilk_increase_wm_latency(dev_priv, dev_priv->wm.pri_latency, 12) |
  

•           ilk_increase_wm_latency(dev_priv, dev_priv->wm.spr_latency, 12) |
  

•           ilk_increase_wm_latency(dev_priv, dev_priv->wm.cur_latency, 12);
  

•   changed = ilk_increase_wm_latency(dev_priv, dev_priv->wm.pri_latency, 12);
  

•   changed |= ilk_increase_wm_latency(dev_priv, dev_priv->wm.spr_latency, 12);
  

•   changed |= ilk_increase_wm_latency(dev_priv, dev_priv->wm.cur_latency, 12);
  
    if (!changed)
            return;
  
  

base-commit: d73b17465d6da0a94bc0fcc86b150e1e923e8f71

2.33.1.637.gf443b226ca

-- Thanks, ~Nick Desaulniers