Am Dienstag, 5. Dezember 2017, 13:35:57 CET schrieb Łukasz Stelmach: Hi Łukasz, > Use memcpy_fromio() instead of custom exynos_rng_copy_random() function > to retrieve generated numbers from the registers of PRNG. > > Remove unnecessary invocation of cpu_relax(). > > Signed-off-by: Łukasz Stelmach <l.stelmach@xxxxxxxxxxx> > --- > drivers/crypto/exynos-rng.c | 36 +++++------------------------------- > 1 file changed, 5 insertions(+), 31 deletions(-) > > diff --git a/drivers/crypto/exynos-rng.c b/drivers/crypto/exynos-rng.c > index 894ef93ef5ec..002e9d2a83cc 100644 > --- a/drivers/crypto/exynos-rng.c > +++ b/drivers/crypto/exynos-rng.c > @@ -130,34 +130,6 @@ static int exynos_rng_set_seed(struct exynos_rng_dev > *rng, } > > /* > - * Read from output registers and put the data under 'dst' array, > - * up to dlen bytes. > - * > - * Returns number of bytes actually stored in 'dst' (dlen > - * or EXYNOS_RNG_SEED_SIZE). > - */ > -static unsigned int exynos_rng_copy_random(struct exynos_rng_dev *rng, > - u8 *dst, unsigned int dlen) > -{ > - unsigned int cnt = 0; > - int i, j; > - u32 val; > - > - for (j = 0; j < EXYNOS_RNG_SEED_REGS; j++) { > - val = exynos_rng_readl(rng, EXYNOS_RNG_OUT(j)); > - > - for (i = 0; i < 4; i++) { > - dst[cnt] = val & 0xff; > - val >>= 8; > - if (++cnt >= dlen) > - return cnt; > - } > - } > - > - return cnt; > -} > - > -/* > * Start the engine and poll for finish. Then read from output registers > * filling the 'dst' buffer up to 'dlen' bytes or up to size of generated > * random data (EXYNOS_RNG_SEED_SIZE). > @@ -171,6 +143,8 @@ static int exynos_rng_get_random(struct exynos_rng_dev > *rng, { > int retry = EXYNOS_RNG_WAIT_RETRIES; > > + *read = min_t(size_t, dlen, EXYNOS_RNG_SEED_SIZE); > + > if (rng->type == EXYNOS_PRNG_TYPE4) { > exynos_rng_writel(rng, EXYNOS_RNG_CONTROL_START, > EXYNOS_RNG_CONTROL); > @@ -180,8 +154,8 @@ static int exynos_rng_get_random(struct exynos_rng_dev > *rng, } > > while (!(exynos_rng_readl(rng, > - EXYNOS_RNG_STATUS) & EXYNOS_RNG_STATUS_RNG_DONE) && --retry) > - cpu_relax(); > + EXYNOS_RNG_STATUS) & EXYNOS_RNG_STATUS_RNG_DONE) && > + --retry); Is this related to the patch? > > if (!retry) > return -ETIMEDOUT; > @@ -189,7 +163,7 @@ static int exynos_rng_get_random(struct exynos_rng_dev > *rng, /* Clear status bit */ > exynos_rng_writel(rng, EXYNOS_RNG_STATUS_RNG_DONE, > EXYNOS_RNG_STATUS); > - *read = exynos_rng_copy_random(rng, dst, dlen); > + memcpy_fromio(dst, rng->mem + EXYNOS_RNG_OUT_BASE, *read); > > return 0; > } Ciao Stephan