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    Subject[PATCH 4.19 012/239] drm/i915: Avoid bitwise vs logical OR warning in snb_wm_latency_quirk()
    Date
    From: Nathan Chancellor <nathan@kernel.org>

    commit 2e70570656adfe1c5d9a29940faa348d5f132199 upstream.

    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.

    Link: https://github.com/ClangBuiltLinux/linux/issues/1473
    Reported-by: Nick Desaulniers <ndesaulniers@google.com>
    Signed-off-by: Nathan Chancellor <nathan@kernel.org>
    Suggested-by: Dávid Bolvanský <david.bolvansky@gmail.com>
    Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
    Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20211014211916.3550122-1-nathan@kernel.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/gpu/drm/i915/intel_pm.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    --- a/drivers/gpu/drm/i915/intel_pm.c
    +++ b/drivers/gpu/drm/i915/intel_pm.c
    @@ -3002,9 +3002,9 @@ static void snb_wm_latency_quirk(struct
    * 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;

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