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From: Nathan Chancellor <nathan@kernel.org>
To: Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	Nathan Chancellor <nathan@kernel.org>
Subject: [PATCH] drm/i915: Avoid bitwise vs logical OR warning in snb_wm_latency_quirk()
Date: Thu, 14 Oct 2021 14:19:16 -0700	[thread overview]
Message-ID: <20211014211916.3550122-1-nathan@kernel.org> (raw)

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>
---
 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


WARNING: multiple messages have this Message-ID (diff)
From: Nathan Chancellor <nathan@kernel.org>
To: Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	Nathan Chancellor <nathan@kernel.org>
Subject: [Intel-gfx] [PATCH] drm/i915: Avoid bitwise vs logical OR warning in snb_wm_latency_quirk()
Date: Thu, 14 Oct 2021 14:19:16 -0700	[thread overview]
Message-ID: <20211014211916.3550122-1-nathan@kernel.org> (raw)

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>
---
 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


             reply	other threads:[~2021-10-14 21:19 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-14 21:19 Nathan Chancellor [this message]
2021-10-14 21:19 ` [Intel-gfx] [PATCH] drm/i915: Avoid bitwise vs logical OR warning in snb_wm_latency_quirk() Nathan Chancellor
2021-10-14 21:21 ` Nick Desaulniers
2021-10-14 21:21   ` [Intel-gfx] " Nick Desaulniers
2021-10-18  9:10   ` Ville Syrjälä
2021-10-18  9:10     ` [Intel-gfx] " Ville Syrjälä
2021-10-15  3:04 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for " Patchwork
2021-10-15  3:36 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-10-15 10:25 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork

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