| Message ID | 1486475501-13541-1-git-send-email-joonas.lahtinen@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Feb 07, 2017 at 03:51:41PM +0200, Joonas Lahtinen wrote: > "BIT(max) - 1" will overflow when max = 32, and GCC will complain. > We already have GENMASK for generating the mask, use it! > > Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> > Cc: Chris Wilson <chris@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..1c06fbb 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, 0); Too simple! BUILD_BUG_ON(BIT(ss_max)-1 != GENMASK(ss_max, 0)); Needs to be GENMASK(ss_max - 1, 0); the high bit is inclusive. Otherwise, the list matches up with a quick grep for BIT*(x)-1. -Chris
On ti, 2017-02-07 at 14:03 +0000, Chris Wilson wrote: > On Tue, Feb 07, 2017 at 03:51:41PM +0200, Joonas Lahtinen wrote: > > > > "BIT(max) - 1" will overflow when max = 32, and GCC will complain. > > We already have GENMASK for generating the mask, use it! > > > > Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> > > Cc: Chris Wilson <chris@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..1c06fbb 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, 0); > > Too simple! > > BUILD_BUG_ON(BIT(ss_max)-1 != GENMASK(ss_max, 0)); > > Needs to be GENMASK(ss_max - 1, 0); the high bit is inclusive. > > Otherwise, the list matches up with a quick grep for BIT*(x)-1. Whoop, seem to have nucleared my kernel config. I think better check if the same warning is triggered too, with GENMASK :) Regards, Joonas
diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c index fcf8181..1c06fbb 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, 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 1b8ba2e..1a0eeb9 100644 --- a/drivers/gpu/drm/i915/intel_fbdev.c +++ b/drivers/gpu/drm/i915/intel_fbdev.c @@ -371,7 +371,7 @@ 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, 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..8258fd6 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, 0)) static struct i915_power_well *lookup_power_well(struct drm_i915_private *dev_priv, int power_well_id)
"BIT(max) - 1" will overflow when max = 32, and GCC will complain. We already have GENMASK for generating the mask, use it! Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Chris Wilson <chris@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(-)