[Intel-gfx] [PATCH v2 1/2] drm/i915: Avoid BIT(max) - 1 and use GENMASK(max - 1, 0)

Joonas Lahtinen joonas.lahtinen at linux.intel.com
Wed Feb 8 13:12:09 UTC 2017


"BIT(max) - 1" will overflow when max = 32, and GCC will complain.
We already have GENMASK for generating the mask, use it!

v2: Majestic off by one spotted (Chris)

Signed-off-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_device_info.c | 2 +-
 drivers/gpu/drm/i915/intel_fbdev.c       | 2 +-
 drivers/gpu/drm/i915/intel_runtime_pm.c  | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
index fcf8181..0891cc0 100644
--- a/drivers/gpu/drm/i915/intel_device_info.c
+++ b/drivers/gpu/drm/i915/intel_device_info.c
@@ -234,7 +234,7 @@ static void broadwell_sseu_info_init(struct drm_i915_private *dev_priv)
 	 * The subslice disable field is global, i.e. it applies
 	 * to each of the enabled slices.
 	 */
-	sseu->subslice_mask = BIT(ss_max) - 1;
+	sseu->subslice_mask = GENMASK(ss_max - 1, 0);
 	sseu->subslice_mask &= ~((fuse2 & GEN8_F2_SS_DIS_MASK) >>
 				 GEN8_F2_SS_DIS_SHIFT);
 
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 281c5c4..e6f3eb2d 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -369,7 +369,7 @@ static bool intel_fb_initial_config(struct drm_fb_helper *fb_helper,
 		return false;
 
 	memcpy(save_enabled, enabled, count);
-	mask = BIT(count) - 1;
+	mask = GENMASK(count - 1, 0);
 	conn_configured = 0;
 retry:
 	for (i = 0; i < count; i++) {
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 66aa1bb..94df466 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -1249,7 +1249,7 @@ static void vlv_dpio_cmn_power_well_disable(struct drm_i915_private *dev_priv,
 	vlv_set_power_well(dev_priv, power_well, false);
 }
 
-#define POWER_DOMAIN_MASK (BIT(POWER_DOMAIN_NUM) - 1)
+#define POWER_DOMAIN_MASK (GENMASK(POWER_DOMAIN_NUM - 1, 0))
 
 static struct i915_power_well *lookup_power_well(struct drm_i915_private *dev_priv,
 						 int power_well_id)
-- 
2.7.4



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