Revision 7f0801e566cc78315e5dc383bf3c3b5b5b436048 authored by Damien Lespiau on 05 February 2015, 19:35:13 UTC, committed by Jani Nikula on 18 March 2015, 08:09:05 UTC
We don't want to end up in a state where we track that the pipe has its primary plane enabled when primary plane registers are programmed with values that look possible but the plane actually disabled. Refuse to read out the fb state when the primary plane isn't enabled. Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Suggested-by: Matt Roper <matthew.d.roper@intel.com> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> Reviewed-by: Matt Roper <matthew.d.roper@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reported-by: Andrey Skvortsov <andrej.skvortzov@gmail.com> Reported-by: Steven Rostedt <rostedt@goodmis.org> Reference: http://mid.gmane.org/20150203191507.GA2374@crion86 Tested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
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dec_and_lock.c
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
/*
* This is an implementation of the notion of "decrement a
* reference count, and return locked if it decremented to zero".
*
* NOTE NOTE NOTE! This is _not_ equivalent to
*
* if (atomic_dec_and_test(&atomic)) {
* spin_lock(&lock);
* return 1;
* }
* return 0;
*
* because the spin-lock and the decrement must be
* "atomic".
*/
int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
{
/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
if (atomic_add_unless(atomic, -1, 1))
return 0;
/* Otherwise do it the slow way */
spin_lock(lock);
if (atomic_dec_and_test(atomic))
return 1;
spin_unlock(lock);
return 0;
}
EXPORT_SYMBOL(_atomic_dec_and_lock);
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