Hi, On Saturday, April 08, 2017 03:32:45 PM Krzysztof Kozlowski wrote: > Replace existing hw_ranndom/exynos-rng driver with a new, reworked one. > This is a driver for pseudo random number generator block which on > Exynos4 chipsets must be seeded with some value. On newer Exynos5420 > chipsets it might seed itself from true random number generator block > but this is not implemented yet. > > New driver is a complete rework to use the crypto ALGAPI instead of > hw_random API. Rationale for the change: > 1. hw_random interface is for true RNG devices. > 2. The old driver was seeding itself with jiffies which is not a > reliable source for randomness. > 3. Device generates five random 32-bit numbers in each pass but old > driver was returning only one 32-bit number thus its performance was > reduced. > > Compatibility with DeviceTree bindings is preserved. > > New driver does not use runtime power management but manually enables > and disables the clock when needed. This is preferred approach because > using runtime PM just to toggle clock is huge overhead. > > Another difference is reseeding itself with generated random data > periodically and during resuming from system suspend (previously driver > was re-seeding itself again with jiffies). > > Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx> > Reviewed-by: Stephan Müller <smueller@xxxxxxxxxx> > Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@xxxxxxxxx> Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics
