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| author | Takashi Iwai <tiwai@suse.de> | 2017-08-02 18:11:45 +0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2017-08-02 18:11:45 +0300 |
| commit | 5ef26e966d3fd105ad9a7e8e8f6d12c7fbd4c03d (patch) | |
| tree | dd5c2ce3daab2e398ab8c0fb852587b647131568 /include/linux/processor.h | |
| parent | 3f3c371421e601fa93b6cb7fb52da9ad59ec90b4 (diff) | |
| parent | 60668a2dcafcf8aad0860f5a5c93eb2d7438052e (diff) | |
| download | linux-5ef26e966d3fd105ad9a7e8e8f6d12c7fbd4c03d.tar.xz | |
Merge tag 'asoc-fix-v4.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus
ASoC: Fixes for v4.13
Quite a few fixes here that have been sent since the merge window, the
biggest one is the fix from Tony for some confusion with the device
property API which was causing issues with the of-graph card. This is
fixed with some changes in the graph API itself as it seemed very likely
to be error prone.
Diffstat (limited to 'include/linux/processor.h')
| -rw-r--r-- | include/linux/processor.h | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/include/linux/processor.h b/include/linux/processor.h new file mode 100644 index 000000000000..da0c5e56ca02 --- /dev/null +++ b/include/linux/processor.h @@ -0,0 +1,70 @@ +/* Misc low level processor primitives */ +#ifndef _LINUX_PROCESSOR_H +#define _LINUX_PROCESSOR_H + +#include <asm/processor.h> + +/* + * spin_begin is used before beginning a busy-wait loop, and must be paired + * with spin_end when the loop is exited. spin_cpu_relax must be called + * within the loop. + * + * The loop body should be as small and fast as possible, on the order of + * tens of instructions/cycles as a guide. It should and avoid calling + * cpu_relax, or any "spin" or sleep type of primitive including nested uses + * of these primitives. It should not lock or take any other resource. + * Violations of these guidelies will not cause a bug, but may cause sub + * optimal performance. + * + * These loops are optimized to be used where wait times are expected to be + * less than the cost of a context switch (and associated overhead). + * + * Detection of resource owner and decision to spin or sleep or guest-yield + * (e.g., spin lock holder vcpu preempted, or mutex owner not on CPU) can be + * tested within the loop body. + */ +#ifndef spin_begin +#define spin_begin() +#endif + +#ifndef spin_cpu_relax +#define spin_cpu_relax() cpu_relax() +#endif + +/* + * spin_cpu_yield may be called to yield (undirected) to the hypervisor if + * necessary. This should be used if the wait is expected to take longer + * than context switch overhead, but we can't sleep or do a directed yield. + */ +#ifndef spin_cpu_yield +#define spin_cpu_yield() cpu_relax_yield() +#endif + +#ifndef spin_end +#define spin_end() +#endif + +/* + * spin_until_cond can be used to wait for a condition to become true. It + * may be expected that the first iteration will true in the common case + * (no spinning), so that callers should not require a first "likely" test + * for the uncontended case before using this primitive. + * + * Usage and implementation guidelines are the same as for the spin_begin + * primitives, above. + */ +#ifndef spin_until_cond +#define spin_until_cond(cond) \ +do { \ + if (unlikely(!(cond))) { \ + spin_begin(); \ + do { \ + spin_cpu_relax(); \ + } while (!(cond)); \ + spin_end(); \ + } \ +} while (0) + +#endif + +#endif /* _LINUX_PROCESSOR_H */ |
