From: Sumit Garg sumit.garg@linaro.org
commit be867f987a4e1222114dd07a01838a17c26f3fff upstream.
Existing RNG data read timeout is 200us but it doesn't cover EIP76 RNG data rate which takes approx. 700us to produce 16 bytes of output data as per testing results. So configure the timeout as 1000us to also take account of lack of udelay()'s reliability.
Fixes: 383212425c92 ("hwrng: omap - Add device variant for SafeXcel IP-76 found in Armada 8K") Cc: stable@vger.kernel.org Signed-off-by: Sumit Garg sumit.garg@linaro.org Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/char/hw_random/omap-rng.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/drivers/char/hw_random/omap-rng.c +++ b/drivers/char/hw_random/omap-rng.c @@ -66,6 +66,13 @@ #define OMAP4_RNG_OUTPUT_SIZE 0x8 #define EIP76_RNG_OUTPUT_SIZE 0x10
+/* + * EIP76 RNG takes approx. 700us to produce 16 bytes of output data + * as per testing results. And to account for the lack of udelay()'s + * reliability, we keep the timeout as 1000us. + */ +#define RNG_DATA_FILL_TIMEOUT 100 + enum { RNG_OUTPUT_0_REG = 0, RNG_OUTPUT_1_REG, @@ -176,7 +183,7 @@ static int omap_rng_do_read(struct hwrng if (max < priv->pdata->data_size) return 0;
- for (i = 0; i < 20; i++) { + for (i = 0; i < RNG_DATA_FILL_TIMEOUT; i++) { present = priv->pdata->data_present(priv); if (present || !wait) break;