| Message ID | 1454411190-15721-7-git-send-email-tvrtko.ursulin@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Feb 02, 2016 at 11:06:24AM +0000, Tvrtko Ursulin wrote: > From: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > > Currently the wait_for_atomic_us only allows for a millisecond > granularity which is not nice towards callers requesting small > micro-second waits. > > Re-implement it so micro-second granularity is really supported > and not just in the name of the macro. > > v2: > * Warn when used from non-atomic context (if possible). > * Warn on too long atomic waits. > > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > Cc: Chris Wilson <chris@chris-wilson.co.uk> This also warns if we attempt to use a variable timeout as well, which is a bonus. > drivers/gpu/drm/i915/intel_drv.h | 27 ++++++++++++++++++++++++--- > 1 file changed, 24 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h > index 779d17a9fcce..af6c1539106f 100644 > --- a/drivers/gpu/drm/i915/intel_drv.h > +++ b/drivers/gpu/drm/i915/intel_drv.h > @@ -63,11 +63,32 @@ > ret__; \ > }) > > +#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT) Ok, that took a little bit of digging to verify. /* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */ > + #define _WAIT_FOR_ATOMIC_CHECK WARN_ON_ONCE(!in_atomic()) > +#else > + #define _WAIT_FOR_ATOMIC_CHECK do { } while(0) > +#endif Hmm, not often that we do indent inside #if, but when it is, it is more typically '# define' > +#define _wait_for_atomic(COND, US) ({ \ > + unsigned long end__; \ > + int ret__ = 0; \ > + _WAIT_FOR_ATOMIC_CHECK; \ > + BUILD_BUG_ON((US) > 50000); \ > + end__ = (local_clock() >> 10) + (US) + 1; \ > + while (!(COND)) { \ > + if (time_after((unsigned long)(local_clock() >> 10), end__)) { \ > + ret__ = -ETIMEDOUT; \ > + break; \ > + } \ > + cpu_relax(); \ > + } \ > + ret__; \ > +}) Ok, Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> -Chris
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 779d17a9fcce..af6c1539106f 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -63,11 +63,32 @@ ret__; \ }) +#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT) + #define _WAIT_FOR_ATOMIC_CHECK WARN_ON_ONCE(!in_atomic()) +#else + #define _WAIT_FOR_ATOMIC_CHECK do { } while(0) +#endif + +#define _wait_for_atomic(COND, US) ({ \ + unsigned long end__; \ + int ret__ = 0; \ + _WAIT_FOR_ATOMIC_CHECK; \ + BUILD_BUG_ON((US) > 50000); \ + end__ = (local_clock() >> 10) + (US) + 1; \ + while (!(COND)) { \ + if (time_after((unsigned long)(local_clock() >> 10), end__)) { \ + ret__ = -ETIMEDOUT; \ + break; \ + } \ + cpu_relax(); \ + } \ + ret__; \ +}) + #define wait_for(COND, MS) _wait_for(COND, (MS) * 1000, 1000) #define wait_for_us(COND, US) _wait_for(COND, US, 1) -#define wait_for_atomic(COND, MS) _wait_for(COND, MS, 0) -#define wait_for_atomic_us(COND, US) _wait_for((COND), \ - DIV_ROUND_UP((US), 1000), 0) +#define wait_for_atomic(COND, MS) _wait_for_atomic(COND, (MS) * 1000) +#define wait_for_atomic_us(COND, US) _wait_for_atomic((COND), (US)) #define KHz(x) (1000 * (x)) #define MHz(x) KHz(1000 * (x))