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author | Chris Wilson <chris@chris-wilson.co.uk> | 2016-12-22 08:36:08 +0000 |
---|---|---|
committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2016-12-27 12:34:00 +0100 |
commit | a33d42dd03352d2e9d3d2c00bfa435c7a5ebab25 (patch) | |
tree | a2d74a1f6f6e31bdf0788d24c66feee224056003 /drivers/gpu | |
parent | cf4a7207b1cb4a3c3fe3aa11a83c9d673722a7f5 (diff) | |
download | linux-a33d42dd03352d2e9d3d2c00bfa435c7a5ebab25.tar.bz2 |
drm: Add a simple generator of random permutations
When testing, we want a random but yet reproducible order in which to
process elements. Here we create an array which is a random (using the
Tausworthe PRNG) permutation of the order in which to execute.
Note these are simple helpers intended to be merged upstream in lib/
v2: Tidier code by David Herrmann
v3: Add reminder that this code is intended to be temporary, with at
least the bulk of the prandom changes going to lib/
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161222083641.2691-6-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu')
-rw-r--r-- | drivers/gpu/drm/Kconfig | 4 | ||||
-rw-r--r-- | drivers/gpu/drm/Makefile | 1 | ||||
-rw-r--r-- | drivers/gpu/drm/lib/drm_random.c | 41 | ||||
-rw-r--r-- | drivers/gpu/drm/lib/drm_random.h | 25 |
4 files changed, 71 insertions, 0 deletions
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index ebfe8404c25f..45a1c7468e88 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -321,3 +321,7 @@ config DRM_SAVAGE chipset. If M is selected the module will be called savage. endif # DRM_LEGACY + +config DRM_LIB_RANDOM + bool + default n diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index b9ae4280de9d..6bb416360ae4 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -18,6 +18,7 @@ drm-y := drm_auth.o drm_bufs.o drm_cache.o \ drm_plane.o drm_color_mgmt.o drm_print.o \ drm_dumb_buffers.o drm_mode_config.o +drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o drm-$(CONFIG_COMPAT) += drm_ioc32.o drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o drm-$(CONFIG_PCI) += ati_pcigart.o diff --git a/drivers/gpu/drm/lib/drm_random.c b/drivers/gpu/drm/lib/drm_random.c new file mode 100644 index 000000000000..7b12a68c3b54 --- /dev/null +++ b/drivers/gpu/drm/lib/drm_random.c @@ -0,0 +1,41 @@ +#include <linux/bitops.h> +#include <linux/kernel.h> +#include <linux/random.h> +#include <linux/slab.h> +#include <linux/types.h> + +#include "drm_random.h" + +static inline u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state) +{ + return upper_32_bits((u64)prandom_u32_state(state) * ep_ro); +} + +void drm_random_reorder(unsigned int *order, unsigned int count, + struct rnd_state *state) +{ + unsigned int i, j; + + for (i = 0; i < count; ++i) { + BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32)); + j = drm_prandom_u32_max_state(count, state); + swap(order[i], order[j]); + } +} +EXPORT_SYMBOL(drm_random_reorder); + +unsigned int *drm_random_order(unsigned int count, struct rnd_state *state) +{ + unsigned int *order, i; + + order = kmalloc_array(count, sizeof(*order), GFP_TEMPORARY); + if (!order) + return order; + + for (i = 0; i < count; i++) + order[i] = i; + + drm_random_reorder(order, count, state); + return order; +} +EXPORT_SYMBOL(drm_random_order); diff --git a/drivers/gpu/drm/lib/drm_random.h b/drivers/gpu/drm/lib/drm_random.h new file mode 100644 index 000000000000..a78644bea7f9 --- /dev/null +++ b/drivers/gpu/drm/lib/drm_random.h @@ -0,0 +1,25 @@ +#ifndef __DRM_RANDOM_H__ +#define __DRM_RANDOM_H__ + +/* This is a temporary home for a couple of utility functions that should + * be transposed to lib/ at the earliest convenience. + */ + +#include <linux/random.h> + +#define DRM_RND_STATE_INITIALIZER(seed__) ({ \ + struct rnd_state state__; \ + prandom_seed_state(&state__, (seed__)); \ + state__; \ +}) + +#define DRM_RND_STATE(name__, seed__) \ + struct rnd_state name__ = DRM_RND_STATE_INITIALIZER(seed__) + +unsigned int *drm_random_order(unsigned int count, + struct rnd_state *state); +void drm_random_reorder(unsigned int *order, + unsigned int count, + struct rnd_state *state); + +#endif /* !__DRM_RANDOM_H__ */ |