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hwrng: omap - Fix RNG wait loop timeout 

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: 383212425c ("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>
This commit is contained in:
Sumit Garg 2019-10-14 17:32:45 +05:30 committed by Herbert Xu
parent e9fc36719b
commit be867f987a
1 changed files with 8 additions and 1 deletions
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9
drivers/char/hw_random/omap-rng.c
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@ -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 *rng, void *data, size_t max,
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;